High Tunnels

Using Low-Cost Technology to Increase Yields, Improve Quality and Extend the Season

By Ted Blomgren and Tracy Frisch

Produced by Regional Farm and Food Project and Cornell University with funding from the USDA Northeast Region Sustainable Research and Education Program

Distributed by the University of Vermont Center for Sustainable Agriculture High Tunnels

Authors Ted Blomgren Extension Associate, Cornell University

Tracy Frisch Founder, Regional Farm and Food Project

Contributing Author Steve Moore Farmer, Spring Grove, Pennsylvania

Illustrations Naomi Litwin

Published by the University of Vermont Center for Sustainable Agriculture

May 2007

This publication is available on-line at www.uvm.edu/sustainableagriculture.

Farmers highlighted in this publication can be viewed on the accompanying DVD. It is available from the University of Vermont Center for Sustainable Agriculture, 63 Carrigan Drive, Burlington, VT 05405. The cost per DVD (which includes shipping and handling) is $15 if mailed within the continental U.S. For other areas, please contact the Center at (802) 656-5459 or [email protected] with ordering questions.

The High Tunnels project was made possible by a grant from the USDA Northeast Region Sustainable Agriculture Research and Education program (NE-SARE).

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the United States Department of Agriculture. University of Vermont Extension, Burlington, Vermont. University of Vermont Extension, and U.S. Department of Agriculture, cooperating, offer education and employment to everyone without regard to race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, and marital or familial status. Any reference to commercial products, trade names, or brand names is for information only, and no endorsement or approval is intended.

Acknowledgements

The generosity, patience and expertise of all the farmers involved in producing this manual and companion DVD was essential to our project. We’d like to thank Keith Cramer, Steve Groff, Seth Jacobs, Andy Jones, Ed Weaver, and David and Ty Zemelsky for their willingness to make their experiences and insights accessible to fellow growers and for remaining committed to our accuracy up until the very end, even when it meant responding to endless questions. We’d also like to thank Bryan O’Hara and Chris Lincoln for sharing their innovative farming experiences with us.

In reviewing the first draft of this manual, the participating farmers were joined by John Biernbaum of Michigan State University, Judson Reid of Cornell Cooperative Extension, Chris Wien of Cornell University, and farmers Michael and Phillip Kilpatrick, each of whom contributed enthusiastically to help strengthen this manual. We are indebted to all of them. Responsibility for this publication’s inevitable errors, however, belongs solely to its authors. Contents

Introduction...... 1

Case Studies Cramer’s Posie Patch...... 2 Weaver’s Orchard...... 7 Cedar Meadow Farm ...... 10 Intervale Community Farm...... 12 Star Light ...... 16 Slack Hollow Farm ...... 20

High Tunnels and Marketing ...... 23

Site Considerations ...... 26

Selecting Your Structure...... 28 Selecting Materials...... 29 Multi-Bay Tunnels...... 33 Walk-In Tunnels (Caterpillars)...... 35 Low Tunnels: An Alternative to High Tunnels ...... 38

Construction Tips...... 40

Environmental Management...... 47 Venting and Cooling...... 47 Heating...... 49 Interior Row Covers...... 50

Soil and Crop Management Soil Management...... 54 Interior Tunnel Layout...... 57 Crop Establishment...... 58

Pest Management Weed Management ...... 60 Managing Diseases in High Tunnels ...... 61 Ecological Insect Management in High Tunnels ...... 62

Glossary ...... 64

Resources ...... 65

Further Information and References ...... 71 Introduction

igh tunnels are inexpensive, assessment and taxation, since they lack While we want to demonstrate how passive solar structures a concrete foundation or footings. high tunnels may be a reasonable option H designed to extend the growing for farmers wanting to extend their season and intensify production. By Co-author and Pennsylvania farmer growing and marketing seasons, high protecting crops from potentially Steve Moore suggests several rules for tunnels are not for everyone. They are damaging weather conditions (frost, high tunnel design: tools, not ends in themselves. To be an temperature fluctuations, precipitation, • Capture as much natural appropriate investment, high tunnels wind, or excess moisture that delays as possible. must suit a farmer’s goals and resources. planting or cultivation), high tunnels • Conserve as much energy as possible. Each grower needs to critically examine also reduce risk and enhance the quality • Keep it simple, both mechanically the pros and cons of high tunnels in the of the harvest. They enable farmers to and managerially. context of their own situation. tap discerning markets hungry for local • Design and operate for minimal products and thus become more economic risk and a quick payback. Some farmers have no interest in profitable. extending the season. A couple farming Unlike culture, where crops at Persephone Farm in Oregon High tunnels have other benefits. They may be grown hydroponically or in flats eloquently expressed this perspective can help farmers better utilize labor by or pots on benches, crops in high (see the September 2006 issue of providing work in bad weather and tunnels are almost always grown in the Growing for Market). They relish their potentially creating year-round positions. ground. High tunnels can be configured off-season downtime and look forward Due to the protected microclimate inside in a variety of shapes (i.e., Quonset or to selling out and shutting down for the the structure, high tunnel crops tend to be gothic) and sizes (narrow or wide, short year. And they are cognizant and of higher quality and produce higher or long, single bay or multi-bay), and accepting of the trade-offs inherent in yields than field-grown crops. As can be semi-permanent, temporary or their decision. inside high tunnels tend to experience movable structures. less disease and insect pressure, fewer This manual is intended to provide pesticides are used. There are also differences between four- farmers, agricultural developers, and season high tunnels (also called “hoop farm advisors with a realistic depiction High tunnels—simple, plastic-covered, houses” or “passive solar ”) of some of the applications for high tubular steel structures—rely mainly on and three-season high tunnels such as tunnels in Northeastern agriculture. We the sun’s energy to warm the soil and Haygroves. Four-season structures—the aim to assist farmers and those who air. Their name is derived from the fact conventional single bay high tunnel— work with farmers in determining if and that they are high enough in which to typically cost about $2 to $3/ ft2 how to make use of high tunnels. As a stand up. European and Asian farmers compared to $0.75 to $1.25/ft2 for a decision-making aid, this publication have used high tunnels for decades but three-season high tunnel. The farmer provides both general principles and this low cost growing environment is case studies and text that follow will specific, in-depth examples as guidance. relatively new in North America. In illuminate the differences between these The manual should enable more farmers recent years, more and more farmers are two types of structures. to use high tunnels effectively, experimenting with their use. enhancing productivity, net income, and In the Northeast, high tunnels are well quality of life, and avoiding some of the Typically high tunnels forgo mechanical suited for the production of high value pitfalls of earlier adopters. systems such as heaters, fans, and lights. crops including salad mix, baby Partially because of the absence of these spinach, fresh market tomatoes, The information and concepts we have amenities, high tunnels are less costly to cucumbers, red peppers, basil, cut chosen to present are based largely on build. Often, however, their frames are flowers, raspberries, , and the observations and experimentation of identical to more conventional more. And dwarf tree-crops like sweet farmers who grow in high tunnels in the greenhouses. Because high tunnels are cherries can be produced in larger Northeast from southern Pennsylvania far less capital intensive than multi-bay tunnels (like Haygroves). to northern Vermont. We have profiled greenhouses, it usually takes less time Farmers may construct high tunnels to six farmers, and also have drawn from for them to pay for themselves. In complement their existing agricultural the experiences of several others. The addition, high tunnels are typically operations or turn to high tunnels as the extensive farming experience of two of classified as temporary agricultural centerpiece of a new stand-alone the three authors has also provided structures for purposes of property business. much of the basis for this publication.

1 – High Tunnels Case Study: Cramer’s Posie Patch

alph Cramer and his son and Flower Growers, the Cramers saw a afterthought, but wholesalers needed business partner, Keith, are homemade light-weight structure. to see quantity. By 2001, four years Rwell-known southern Using it as a model, they built their after they decided to seriously grow Pennsylvania cut and dried flower own 1/6 acre tunnel, but a 20 mile per fresh cuts, they accounted for more farmers. They are also pioneers in the hour wind blew it down. than half of total sales. Producing both usage of multi-bay high tunnels. fresh and dried flowers for different Ralph serves as the Eastern U.S. sales Keith explains why their experimental markets has given the Cramers a agent for Haygroves, manufactured in high tunnel failed. “The hoops in our broader range of options than they Great Britain. Their one acre of homemade structure were made from previously had. Haygrove high tunnels complements rebar inserted through PVC pipe (to the other 49 acres of annuals, protect the plastic from rubbing), but Most of the Cramers’ fresh cuts go to perennials (15 acres), and woody the rebar was not strong enough to 20 major wholesale florists in the ornamentals (4.5 acres) that include resist the wind pressure. We also had mid-Atlantic, from New York’s 130 varieties of flowers at Cramer’s aligned our tunnels in a North/South Finger Lakes region to Washington, Posie Patch. configuration—which placed them D.C. Downward price pressures and sideways to the prevailing winds, the logistics of getting a truck into and Ralph Cramer’s parents, Lewis and making them even more vulnerable. out of the city by 7 A.M. have led Mary, were also Lancaster County We had no experience or advice about them to avoid New York City buyers. farmers. Lewis teased his wife Mary venting tunnels to prevent damage. A typical buyer will receive delivery about her “little flower growing We had no top rail or gantry of any of 20 buckets of flowers from hobby” so she began to keep records type, thus the ropes could not be Cramers’ Posie Patch once or twice a of the profit from her flowers and pulled tight to prevent the plastic from week. (unbeknownst to him) his tobacco. shifting and becoming a spinnaker in The next year, when he saw the the wind.” Working with large-scale wholesale figures, he wasn’t laughing anymore, buyers can be demanding. Early every said Keith. The couple developed Primed to grow in a multi-bay high morning, Keith faxes an availability several famous lines of cockscomb tunnel, the Cramers discovered list to these buyers. Each buyer’s that their son and grandson continue Haygroves and they traveled to order becomes a cut list assigned to to raise and sell as improved varieties. England to see where they were the farm’s eight-person field crew. commercially available. The structure They cut, grade, and do quality Ralph bought an additional farm in impressed them, as did the Haygrove control as piecework in the field. another part of the county and company’s responsiveness to farmers’ Availability lists are saved to guide continued to grow flowers on its silty needs and ideas. planning for the next year’s planting. loam fields. Land quality is very good on this current site, and two streams By enabling them to sell cut flowers Bouquet makers who sell to big box allow for overhead irrigation of direct both earlier and later and greatly stores like Costco are another seeded annuals when rainfall is low. improving size and quality in some category of buyer that take a However, compared to the old farm cases, Haygroves have boosted the significant volume of their flowers. perched on top of steep hills, this farm Cramers’ business far out of For some flowers, these buyers are is somewhat of a “frost magnet” with proportion to the growing space they looking for different characteristics a shorter growing season, and the cover. With these structures, the than the wholesale florists, providing coldest field is also their wettest. The Cramers achieve larger blooms and the Cramers with a market for smaller farm is classified as Zone 6B or a cold greater stem length for certain species stems. Zone 6, with fall frost around the first and protect their flowers from disease week of October and the last frost free and wind injury. Cramer’s Posie Patch also ships dried date around May 15. flowers to designers and florists For many years the farm had only sold nationwide; sells seeds to commercial Before they purchased their first dried flowers. But the market for dried growers and three large seed Haygrove, they were looking for some flowers is “soft,” and storing dried companies (Gloeckner, Germania and sort of multi-bay stock hurts cash flow and takes up Johnny’s); and has a small, dried structure. At a West coast meeting of considerable barn space. The Cramers flower shop at the farm. the Association of Specialty Cut had trialed fresh flowers as an

2 – High Tunnels Large multi-bay tunnels make sense or the field. This represents a huge like cut flower species requires for the Cramers’ production needs. increase in profit. prolonged cool temperatures to With routine sales of 800 bunches at a develop stem length but cannot time, they would rapidly clear out a Chili peppers grown in Haygroves tolerate frost. They moderate single 30' x 100' high tunnel. Smaller, have become an important element of temperatures by keeping the lisianthus single-bay high tunnels are also less the farm’s product mix. High tunnels bay open unless frost threatens, accessible for tractors and so require allow them to grow bigger peppers, covering the beds in white plastic to more hand labor. early harvest, and 3' stems (compared reduce soil warming, and using shade to 14" or 16" for field-grown). In the cloth. In the Haygroves, lisianthus The cost per square foot under cover tunnel most chili harvests begin in the stems reach 3' in length (versus 9" in is lower in Haygroves than in single- first week of August rather than at the the field). “My customers are not bay high tunnels. A one-acre first frost (late September or early interested in anything shorter than 20- Haygrove costs about $28,000 (2006 October) in the field. They grow the 24" stems,” says Keith. price), including shipping and chilies in the warmest bay, which they polyethylene film and the Cramers vent less and irrigate more than the Hydrangeas (Paniculata grandiflora) expect 15 to 20 years of use. other bays. are the first woody perennial the Cramers have tried in the Haygroves. The Cramers take full advantage of In the Haygroves, the first sunflowers They have been rewarded with more the ability to manage each high tunnel are harvested 3-1/2 weeks earlier. rapid growth and impressively large bay independently. This flexibility Local sunflowers are most in vogue in flower clusters. The trial was so allows them to tailor venting, shading, May, June and the first part of July, successful, the Cramers have added a and irrigation practices to the and early sunflowers help with full bay (approximately 600 plants) of temperature and perennial sales. The Cramers grow the variety ‘Limelight.’ requirements of individual crops that seven visually identical varieties of fill a bay. With some experimentation, pollenless sunflowers with different Making the right decision about when they identified species that are maturation dates. Their early to cover multi-bay high tunnels is especially rewarding for them to grow sunflowers get them in the door with critical in regions with the possibility in Haygroves. These include their customers so they can sell other of late snowfall. The Cramers want to cockscomb, sunflowers, chili peppers, species of early field-grown flowers. get the biggest jump on production lisianthus, dahlias, and hydrangeas. They double crop sunflowers, so after that they can. Yet if they cover the the early crop is done, they remove tunnels too early, they run the risk that Cockscomb (Celosia) is the hallmark the plants, make new holes in the a late snowstorm will damage the flower of Cramer’s Posie Patch. plastic, and seed sunflowers for structure, as they are not engineered Keith’s grandparents selected this harvest after the frost. for snow load. In their southern seed, and he and his father continue to Pennsylvania location, they generally do. In two bays the farm grows During Hurricane Isabelle and other cover the tunnels around April 7 and cockscomb as a cut flower. Once catastrophic wind and rain events, cut them in mid-April. In the Spring Celosia plants are established, warm flower plantings in the Haygroves of 2003, the structure withstood 5" of temperatures (80oF) will promote were barely affected. With their wet, heavy snow. They were able to flowering better than cool tunnels fully vented for the high “bump it off” without incident. temperatures (below 50oF). Height of winds, the tops kept approximately cockscomb is significantly greater, 4' 80% of the soil dry. The tunnels They aim to ‘hibernate’ (remove) the to 4-1/2' in the Haygrove versus 3' in diffused the wind as it moved through tunnel plastic in mid-October. They the field. The Haygrove also permits them. Straight line winds and bring the top poly from two adjoining harvest to begin around July 6, a saturated soil combined to level tunnels into the shared leg row, cover month earlier than field-grown. outdoor crops, including transplants it with black plastic row mulch to on black plastic mulch. Sunflowers prevent UV degradation, and secure it This four or more week harvest inside remained safe and sound while with tomato twine. They remove the advantage and superior quality brings those in the field were uprooted. doors and store them in the barn. Over a price that is 30 to 40% higher ($4.15 the winter, they leave the side curtains per bunch versus the $2.95 bunch The Cramers could not grow hanging on the structure. price). They have been able to marketable lisianthus outside, but do maintain that high wholesale price for so consistently in the Haygroves, The first year they grew in the all cockscomb stems cut during the where they raise 1/6 acre of the flower Haygrove, the Cramers gave their season, whether grown in the tunnel in four colors. This high-value, rose- crew responsibility for recording daily

3 – High Tunnels high and low temperatures in each As controlling foliage wetness is a aphids and several different miticides bay. This data taught them that the major high tunnel benefit, the in rotation to avoid resistance. normal temperature fluctuation is Cramers only use drip irrigation in the okay. They monitor the tightness of Haygroves. “We don’t want to make it In retrospect, the Cramers realize that the ropes monthly. During rain inside a tunnel,” explains Keith. a simple procedure would have thunderstorm season, they keep the Using transplants makes it feasible to eliminated weed pressure in the leg tunnel fully vented for temperature use drip tape. Were they to direct rows between bays. Before drilling control, with doors open and the roof seed, they would need to cultivate, the tunnel legs into the soil, they clipped in the open position. As this is which would damage drip tape. They recommend making a shallow furrow also the proper way to vent for high use double drip tape per bed. (for runoff control) and pinning down winds associated with thunderstorms, narrow strips of black weed barrier storms require no special intervention. Haygroves vent high and provide fabric. In the absence of this excellent air exchange, therefore prophylactic action, the Cramers Blessed with good Lancaster County humidity is not a problem. Alex Hitt, apply Roundup. In the growing beds, soils, the Cramers use a one-size-fits- who grows organic heirloom tomatoes plastic mulch eliminates the need for all fertilizer program, the same in the in Haygroves and in single-bay mechanical cultivation or herbicide Haygroves as outside. They apply a tunnels in Graham, North Carolina, applications, although some weeding 19-19-19 fertilizer at the rate of 50 attributes the reduced disease of plants must be done by hand in the plant pounds of actual nitrogen per acre. in the Haygroves to their superior holes. After incorporating the fertilizer, they ventilation. The internal humidity is chisel plow, disc and lay plastic similar to outside conditions when Mid-weight floating row cover mulch. vented. protects tender transplants coming from the greenhouse. Their crew lays For their Haygrove plantings, the Powdery mildew is more prevalent this row cover over low wire hoops Cramers use a flat plastic bed layer to under the dry conditions common to straddling the beds. Eventually, when apply 5' wide plastic mulch over a 4' these high tunnels. The Cramers the transplants outgrow the hoop, the wide planting area. They can just fit sometimes have powdery problems in row cover is removed. They use wide four of these beds per 24' bay. These the field during dry periods of the enough fabric to reach from one side are not raised beds because their season as well. Oxidate and Zerotol of the bay to the other. When they pull raised bed shaper/plastic layer cannot are hydrogen peroxide products that it off, they move it to the center of the squeeze four beds into a bay. They they have used successfully to control bay (keeping it out of the leg row vary the color of the plastic mulch this disease. As an added bonus, these where it could get wet), between the depending upon whether they want to pesticides have zero re-entry periods. second and third beds. warm or cool the soil. Chiseling in the They prevent powdery mildew from fall helps the soil dry out faster in the spreading by exploding the spores so These covers must be carefully spring, when they do most of their soil they can’t attach to plant tissue. managed to control excessive preparation and the plastic mulch Existing powdery mildew growth— temperature and humidity. The laying. They would like to fully which has a grey powdery look—is Cramers learned the hard way. “The prepare the beds in the fall but winter not affected by these products; first year, we cooked over 4,000 winds loosen the plastic mulch. therefore, detecting this disease sunflowers,” Keith recalls. In the problem early is essential as flowers spring, they can avoid excessive heat Only transplants, set by hand, are used with grey mildew are obviously not and provide adequate airflow just by in their Haygroves. First, to correctly marketable. opening the doors. A west wind keeps space holes in the plastic mulch, they the air moving. When they have a use the waterwheel from a Under the Haygroves (as with stretch of cloudy weather followed by transplanter behind a tractor. While greenhouses), dry season pests like sun, they find it is important to transplants mitigate risk, they require aphids and spider mites are remove the row cover and let the much more labor. In contrast, in the accentuated. The structures offer a breeze in the doors. This dries out the field they direct seed about 80% of perfect micro-climate and protect plants’ micro-environment, preventing their annuals—with two acres of these pests from rain washing them disease. It also hardens off the plants. seeding scheduled every two weeks. away. Keith relies on chemical Only about five acres of flowers are pesticides to control these pests, such Haygrove recommends that the doors transplanted in the field. as the broad-spectrum of the tunnel be aimed at the organophosphate Orthene against prevailing winds usually from the West. This satisfies ventilation needs

4 – High Tunnels and protects the structure from severe outside production and rely on fewer popular with the major wholesale winds. Many greenhouse designs workers. florists they supply. Being the first suggest a North-South orientation for local grower with certain crops creates even sunlight on the plants because Haygrove Tunnels have fit nicely with a definite customer loyalty. At the end the trusses create quite a bit of shade. the farm’s recent shift in emphasis to of each season, most of his customers High tunnels have a lot less overhead fresh cut flowers. The novelty of tell Keith, “Don’t forget me next year steel to shade plants. Adequate light having local flowers earlier than other when you have the early stuff!” has not been an issue in the Haygrove area growers makes the Cramers tunnels. Enterprise Budget for Cockscomb in One Bay (1/6 Acre) of a One The Cramers use shade cloth on Acre Haygrove Tunnel at Cramer's Posie Patch lisianthus to reduce ambient temperature and elongate the stems by Fixed Costs reducing light. Rather than covering Construction Costs Materials Labor the top of the high tunnel with shade High tunnel construction $3,000 net, they put it underneath—inside the High tunnel frame $25,000 tunnel. If it were outside, venting Subtotals $25,000 $3,000 would become more difficult. Keith explains, “Our shade net is rolled out Total Construction Costs $28,000 on top of ropes that we tie across the Fixed Costs bay. They are approximately 7 feet High tunnel construction (divided by 15 years) $1,867 above the soil, so we can walk under Interest (construction financed at 7% for 15 years) $980 them. If needed, we can move the Taxes, land, office expenses, fees $222 shade across the bay and store on the Total Fixed Costs $3,069 north side to give full sun to the crops.” Total Fixed Costs per Bay (1/6 Acre) $511

After four years of use, the Cramers Variable Costs per Bay (1/6 Acre) are replacing their polyethylene cover Materials and Machinery with an improved greenhouse film Seeds and growing out plugs $357 called Luminance. It is designed to Fertilizer, lime and compost $10 deflect a portion of infrared rays, Irrigation supplies $68 reducing the highest temperatures in Plastic mulch and row cover $90 the tunnel. Some light is lost with this Pesticides $70 feature so to offset the loss, Poly covering (divided by 4 years) $200 Luminance diffuses light, sending the Delivery costs $230 available light into the plant canopy at Subtotal $1,025 different angles. Labor Costs ($11/hr) Cover installation and removal $110 Cramer’s Posie Patch faces some Bed preparation and fertilization $22 difficult choices in charting its future , laying drip tape and mulch $380 course. One weak link is labor. Eight Pruning, trellising, irrigating, spraying, venting $220 Harvesting, grading, packing $2,400 Mexican laborers legally brought into Sales and delivery ($14 to $20/hr) $366 the country on the federal High tunnel clean-up $132 government’s H-2A Agricultural Subtotal $3,630 Guest Worker Visa Program constitute the farm’s field crew. Keith Total Variable Costs per Bay $4,655 tolerates the program’s “red tape nightmare because it provides the Total Costs per Bay $5,166 qualified, legal, dependable workers Revenues per Bay* $20,125 needed to operate profitably.” To add more workers would require building Net Returns per Bay $14,959 more housing, and adding septic, electric, and other infrastructure. *Revenues are based on a harvest of 4,800 bunches per bay and a selling Alternatively, they could reduce price of $4.15/bunch (plus a total of $105 in delivery fees).

5 – High Tunnels Prior to the first fall frost, the look forward to the more relaxed has weakened so it is difficult to get Cramers’ customers start to look to environment of standing orders, even the higher prices needed to justify other suppliers in California, Holland, though the product is not quite as nice tunneled production. With only an and South America. The uncertainty or nearly as fresh. acre of tunnels, the Cramers cannot of the first frost date is a concern for protect both the quantity and diversity their customers since they need to Timing the late season crop is an on- of product that their wholesalers have a continuous supply of flowers. going challenge since the hard frost is demand. For these reasons, the The summer season is very intense for unpredictable. Cramers have decided concentrate on all involved, with daily availability getting a jump on the harvest early, updates and a compressed schedule. Moreover, by the time that hard frost rather than keeping it going after the Keith says that most of his customers ends the harvest, the wholesale market fall frost.

6 – High Tunnels Case Study: Weaver’s Orchard

eaver’s Orchard in Berks first multi-bay tunnel over seven-year- major cause of crop loss in the County, Pennsylvania is a old dwarf sweet cherry trees. The uncovered cherry blocks. Rain- Wthird generation, 100-acre three-bay tunnel covered 0.6 acre; each induced cracking and disease makes family farm. Like many tree fruit bay is 28' x 300'. In 2004, the Weavers cherries unmarketable. Rain at the growers trying to survive in today’s constructed a 0.9 acre Haygrove over wrong time also causes other competitive environment, Ed Weaver five-year-old cherry trees. These problems in the field. believes in diversification and direct tunnels were longer, with two 28' x marketing. The farm grows a number 450' bays and one 20' x 450' bay. Each Keeping rain out with the tunnels and of fruits and vegetables to bay accommodates two rows of trees, using drip irrigation to even out complement the primary crop of spaced 9' apart in the row and 15' moisture levels has been an effective apples. The farm’s on-site market has between rows. solution. High tunnel coverage become a primary sales outlet and the provides insurance that the orchard farm offers a pick-your-own option In two years, the Weavers had put will provide a consistent supply year for small fruits (such as blueberries, almost one-third of their sweet cherries after year, which is no small matter strawberries, and brambles) and for under plastic. Later, they added more when it comes to retaining its place in peaches, apricots, plums, nectarines, Haygrove tunnels for growing tabletop the market. cherries, apples, and pears. With these strawberries, brambles, blueberries, features to attract a good clientele to and 1/3 acre of tomatoes. The multi-bay tunnels make it the farm, the business is able to sell possible to leave cherries on the tree half of its farm’s production retail. During some years, Haygrove tunnels longer, so they can reach optimal size can mean the difference between an and maturity. For uncovered cherry Ed’s grandparents purchased the farm abundant high quality crop and plantings, a grower’s only defense in the 1930s where they grew virtually no crop. On this southeastern against the threat of rain has been to vegetables, fruits, and tobacco. Under Pennsylvania farm, losses might reach pick early. Staying on the tree longer Ed’s management, the farm produced as high as 90% in the uncovered makes the cherries sweeter and tree fruit, vegetables, and strawberries orchard blocks, while only 2 or 3% of bigger. Ed Weaver estimates as much until ten or twelve years ago, when he the crop is lost on trees protected by as a 20% potential weight gain in the added blueberries and brambles. the Haygroves. tunnel-grown cherries harvested. This enhanced yield helps pay for the costs Sweet cherries have been an important Cherries remain one of Ed’s most of the tunnels. On the other hand, crop on the Weaver Farm for three promising crops under plastic. Beyond increased heat under cover around decades. In the late 1990s, frustrations affording protection from adverse harvest time can soften cherries and with standard rootstocks convinced weather and birds, they offer other reduce their quality, so proper venting Ed to expand their acreage with new significant benefits. For a number of of the tunnels is crucial. dwarfing rootstocks. The dwarf trees reasons, cherries grown under come into full production much more Haygroves tend to have higher fruit Bad weather ordinarily prevents farm quickly and are easier to manage. But quality. Their quality also lengthens tasks from being performed in a when his first dwarf trees began shelf life. timely fashion and interrupts harvest. producing, cherry yields were hurt by However, inside the Haygroves, farm frost, rain, and birds. The damage was The Haygroves’ minimal frost employees can work even when it is so great that Ed decided he had to find protection has been enough to protect raining or wet. Similarly, the rain is a way to protect the crop or else the earliest varieties, which flower less of a deterrent for U-pick remove the trees. when temperatures can still drop customers when they can harvest below freezing. These structures can cherries under cover. Searching for a way to protect the trees advance the ripening of early cherry led the Weavers to discover Haygrove varieties up to one week. And In addition to protecting the fruit from multi-bay high tunnels at a spring 2003 earliness can raise the price 30 or 40 disease by keeping off precipitation trade show. Subsequently, Ed took a cents a pound or more. and preventing lingering wetness, growers’ tour to England to see how Haygroves have also reduced bacterial these tunnels are used on another Rain is an important risk factor for a canker at Weaver’s Orchard. This continent. Full of enthusiasm, that delicate fruit crop like cherries. disease organism can enter pruning spring the Weavers constructed their Excess rain at or near harvest time is a wounds. The Weavers prune their

7 – High Tunnels trees following the cherry harvest and application, spraying, and mowing. At the field). At 30 pounds of production leave the Haygroves covered until late Weaver’s Orchard, a granular per tree and 400 trees per acre, Ed August, after the wounds have healed. fertilizer is applied in early March, extrapolated a yield of 12,000 pounds before the tunnels are skinned, so that per acre and a $30,000 gross income Plastic bird netting around the precipitation will water it in. Growing at the pick-your-own price of $2.50 perimeter of each tunnel—to close off season fertility is provided with per pound. Ed estimates that this is the sides and ends—is sufficient to fertigation. All watering is done with about twice the outdoor yield of keep birds out of the trees. Bird drip irrigation. varieties that produce consistently. damage and consumption in an However, accurate comparisons with average year destroys about 15 to Weaver’s Orchard is situated on rocky outside production are difficult, given 20% of the cherry crop outside of the soil and the terrain is uneven. The soil differences in age and varieties. tunnels and, in a dry year, bird and topography make erecting damage can be greater. Haygroves or any other type of tunnel On the other hand, about half of the a challenge. Weavers’ trees in the 2004 Haygrove Counter to these benefits are the ways tunnels s are varieties that are that Haygrove structures complicate None-the-less, Ed Weaver believes that especially challenging to pollinate. cherry production. Much of the work the Haygroves are paying for Even outside of the tunnels, these relates to the plastic itself. The themselves. More importantly, these varieties characteristically produce a structures must be covered each structures are allowing the farm to good crop only two years out of three. spring and uncovered in late summer. lessen the risk of crop loss and have But in the Haygroves, their production And the down side of keeping rain off profitable, high quality cherry harvest was down a surprising 85% in 2005. a crop is the need to irrigate. every year. He estimates that an By bringing in more bees and planting increase in the value of the crop by just more varieties as pollinators in the The Weavers use bumblebees to $0.40 per pound will pay for the annual block, they are trying to address this ensure pollination. Early flowering cost of the tunnel over its lifetime. problem. Recent releases of self- can occur when it is still too cold for fertile varieties are also relevant. The honeybees to be active. And these Given the investment, Ed counsels shortfall in fruiting reduced yields by bees can become disoriented in high other growers to maximize the about $5,000 an acre (wholesale gross tunnels. Honeybees fly repeatedly to efficient use of space in Haygroves. revenues) and cut net income by at and from their hive, while bumblebees He was unable to do so with his first least $3,500 per acre. spend the entire day away from their Haygrove structure as it was colony. Advance (six weeks) notice is constructed over an existing cherry Despite some disappointing yields in required to order bumblebees and the planting and that orchard block was the 2004 block, Ed remains optimistic timing of an order can be changed if not spaced at the optimal high density. about growing cherries in these multi- blooms are slower than anticipated. bay high tunnels. They have solved They have almost doubled tree density some otherwise intractable Erratic weather conditions call for in the new blocks they are planting problems—most significantly those more intensive tunnel management. with the intention of covering them caused by rain and birds. And with Venting is fairly easy, but requires with Haygroves. Ed noted that new several years of experience and vigilance. If it gets hot or if a studies have demonstrated how cherry investigation, he has good ideas about thunderstorm threatens, the Haygroves growers can intensify production by approaches to cultural practices, must be vented. When rain is forecast, increasing the fruiting to vegetative varietal selection, and planting density the tunnels must be closed down. wood ratio. They hope to develop to overcome other snags in his plan. more fruiting wood in each tree by It can be inconvenient to work around paying more attention to tree training. Ed also is exploring the value of and inside the Haygrove structure and Haygrove production for other crops. for a tree fruit grower, this Yields depend a great deal on the Berries are important in the crop mix disadvantage is magnified. Because the variety. Rainier, a superior tasting at Weaver’s Orchard, though the tunnels are 14' or 15' high at the peak, variety, has performed at the top. It Weavers are new to growing berries the cherry trees must be pruned back to also commands a higher price and in Haygroves. Their protection from 12'. Putting up Haygroves over existing Weaver’s Orchard sells pre-picked birds and rain has reduced damage trees is awkward, though doable. Raniers for $4.99 per pound, a dollar and disease and improved quality for per pound more than dark cherries. all types of berries. In the high The tunnels are spacious enough to They have 100 producing Rainier tunnels, both the blueberries and drive a tractor inside for fertilizer trees in their Haygrove (and none in brambles also produced “super

8 – High Tunnels vigorous” canes heavy with fruit that Enterprise Budget for Sweet Cherries in a One-Acre Haygrove Tunnel at required either temporary or Weaver's Orchard additional trellising, respectively. Ed Fixed Costs calls this “a good problem!” Blueberries ripened earlier (three to Tunnel Construction Costs Materials Labor four days to a week or more) than High tunnel construction (220 hrs. x $10/hr) $2,200 field grown berries, but the farm did High tunnel frame $25,000 Irrigation $630 not gain much added value with Subtotals $25,630 $2,200 earliness for this crop. Total Tunnel Construction Costs $27,830 The Weavers have the least Cherry Tree Establishment Costs Materials Labor experience with bramble production Trees (@ $10.25) $4,100 $2,300 in the Haygroves as their first crops Stakes and guards $1,312 under plastic were harvested in 2005. Fertilizer, pesticides, etc. $237 Summer and fall bearing bramble Subtotals $5,649 $2,300 crops—Black Raspberry, Primacane Red Raspberry, and Floricane Red Total Cherry Tree Establishment Costs $7,949 Raspberry—were successful. The Summary of Annual Fixed Costs biggest benefit is that the cover keeps High tunnel construction (divided by 15 years) $1,855 the canes and fruit dry. Pickers don’t Interest (construction financed at 7% for 15 years) $974 have to wait until the dew has dried, Taxes, land, office expenses, fees $295 and with fewer blemishes, the fruits Cherry tree establishment (divided by 15 years) $530 are easier to pick. Shelf life has Total Fixed Costs $3,654 increased, with no mold evident a day after picking. Ed wonders, though, if Variable Costs the lower productivity of black Materials and Machinery raspberries, compared to reds, justifies Fertilizer and lime $47 the cost of planting in the Haygroves. Bees for pollination $220 Pesticides $244 Ed has experimented with several Poly cover (divided by 4 years) $1,000 production systems, Marketing Costs $800 including day-neutral varieties and Subtotal $2,311 June-bearing varieties in tabletop Labor Costs ($8 to $12/hr) production. He is optimistic about Poly cover installation, removal, venting $1,200 Pruning, irrigating, spraying $158 growing tabletop strawberries, which Harvesting, grading, packing $3,706 are common in the United Kingdom. Sales and delivery $880 This system gives the grower Subtotal $5,944 flexibility in timing the fruiting of the crop. Plants are started in trays on Total Variable Costs $8,255 pallets in another hoop house. At blossom, they are moved to the Total Costs $11,909 Haygrove. After production ends, they Revenues* $17,780 are returned to the other hoop house. Planting date, pinching primary buds, Net Returns $5,871 temperature, and the date the plants are moved to the Haygrove are among *Revenues are based on yields of 5,760 lb/acre and an average wholesale price of the factors the grower can manipulate about $2.10/lb. The Weavers wholesale nearly half the total crop to their own to alter the harvest date. farmstand, and then retail the cherries for an average of $4/lb, increasing their revenues by $1.90/lb, or by just over $4,200 (after marketing costs) in profits per By keeping rain off the plants with the acre. Because not all the cherry trees produced a full crop, yields were reduced by tabletop system, the Weavers have about 50%, having a large impact on net returns. been able to grow a June-bearing quart. The Weavers’ experience with with disease problems. Ed Weaver is strawberry crop with a longer shelf ever-bearing (day-neutral) eager to experiment with growing life and no pesticide application. They strawberries grown in the ground was strawberries that ripen out of season, retailed their crop for $1 more per less promising, as they were afflicted in May, and in the Fall.

9 – High Tunnels Case Study: Cedar Meadow Farm

teve and Cheri Groff, and their Steve was also attracted to the scale of than it does in the field, but also three children, live in the Haygrove. One multi-bay unit continues to trial other early varieties. S Holtwood, Pennsylvania, in would give him an entire acre of In the future, Steve plans to use row southern Lancaster County. On rolling tomatoes under cover. Finally, he covers inside the tunnel in early land near the Susquehanna River, they liked the fact that the structure was spring to extend the season even produce 210 acres of small grains and tractor-accessible, giving him greater longer. He is also looking into options vegetables including no-till tomatoes, flexibility to perform tillage and other for supplemental heat as a means to pumpkins, and sweet corn. Steve has operations with machinery. prevent frost injury and to boost become known for his success with a spring growth. permanent cover cropping system in Steve’s tunnel has six bays that are 24' which he establishes vegetable crops wide and 300' long. To maximize its Steve has used bumblebees to get without tillage and makes use of cover use, Steve planted 6,000 plants in the better pollination but questions if they crops and crop rotations as a way to first season, but the result was tall and are necessary, especially since he save soil, reduce pesticides, and leggy plants. He sought to control the likes to occasionally vent on windy increase profits. vegetative growth by reducing days to control plant growth and nitrogen rates and watering, which did lower humidity. Like many no-till farmers, Steve has seem to retard growth but also noted that because soils remain colder resulted in smaller tomatoes. In his first year, Steve had yields of under no-till conditions, they tend to 2,400 25-lb boxes (60,000 lb.) of #1s produce later crops. Steve grows nine The next year, Steve reduced the plant and #2s. In his second year—after acres of no-till tomatoes, and his population to 4,800 plants per acre fine-tuning crop spacing, fertilization, inability to capture the lucrative early and was pleased with the results. In and irrigation—tomato yields market had been a frustration. his first year, Steve planted into bare increased to 3,400 boxes per acre, ground and had a difficult time with 70% of which were #1s. His four-year Steve had been growing some weeds despite using herbicides. In the average annual yield for Haygrove- tomatoes in a 15' x 96' high tunnel for second season, he formed raised beds grown tomatoes was 71,531 pounds. nearly seven years, and was pleased and installed a woven plastic ground with the benefits a high tunnel offers cover, which resulted in a warmer soil Steve’s second season in the including earliness, improved fruit and effective weed suppression. He Haygrove tunnel was a particularly quality, and increased yields. But he plans to maintain the beds wet one, and yields of the same wanted to produce his early tomatoes permanently and to reuse the mulch tomato variety in the field were only on a much larger scale. So, four years and stakes. 1,200 boxes per acre. The three-fold ago, Steve built a one-acre, multi-bay increase in tomato yields was just one Haygrove tunnel. Steve now makes weekly nitrogen of the benefits of the tunnel. The applications through a drip irrigation quality of tunnel-grown fruit has been Steve’s decision to purchase the system, and vents to control excessive vastly superior to field-grown fruit. Haygrove tunnel was based primarily growth. He irrigates three times each “We see it every time we bring high on economic considerations. The week, providing 3 pounds per acre of tunnel tomatoes into the grading room initial cost of the structure, 6 mil nitrogen per watering. In the past, he and compare them with field-grown plastic cover, and mulch, with about used calcium nitrate and liquid tomatoes,” says Steve. 250 hours of labor for assembly, was nitrogen. Now that he has established about $30,000. On a square-foot basis, permanent, mulched beds, he will use Steve has found the effects of severe that was less than half what a high a complete fertilizer beginning soon weather and disease pressure to be tunnel would have cost him to build. after planting. noticeably reduced inside the tunnel. Steve calculates the annual cost of He sprays occasionally, finding that maintaining his acre of Haygroves at Steve sets his plants out during the he gets good coverage by using an air- $4,000. This figure includes one-third third week in April, and harvests from blast sprayer from both ends. The of the cost of the polyethylene film, the first week of July until early natural movement of air inside the which he replaces every three years, November. So far, he has been tunnel helps deliver the pesticide to labor for covering the structure in the pleased with the variety, Mt. Spring, plants in the middle of the structure. spring and uncovering it in the fall, finding that it performs well for a Last year, Steve struggled with a and labor for venting. much longer period inside the tunnel bacterial problem, and is re-evaluating

10 – High Tunnels his use of the permanent ground cover Installing the plastic in the spring is a Beginning around June 15, Steve and stakes that may harbor the big job. Six people can do it on a calm opens the tunnel and removes the pathogen over the winter. He has also day, but eight is better, especially if it doors for the rest of the season. If high struggled with spider mites, and is becomes breezy. Steve says that the winds are expected, Steve fully vents seeking an alternative to miticides for key is to be prepared for that calm day the tunnel, as Haygrove recommends, their control. when plastic installation will go to avoid damage to the structure. smoothly. He estimates that installing When properly constructed, these Although Steve is experimenting with the plastic cover and end-wall doors tunnels are designed to withstand 70 raspberries in one bay of the tunnel, takes about 50 labor hours every mph winds. Steve had some he is not planning on rotating out the spring. experience with high winds—in the tomatoes. He has considered field, tomatoes and sweet corn had relocating the tunnel if he finds that Once the tomatoes are planted, it is blown down but his tomatoes in the tomato pest populations increase to important to ventilate the tunnel multi-bay tunnels remained unfavorable levels, but he estimates properly, which Steve describes as an unscathed. that may cost up to $4,000. He art that comes from experience. “You believes that the experience of have to make venting decisions based Steve believes that he has realized his erecting the tunnel the first time will on temperature, wind speed and objectives with the Haygrove tunnel. enable him to reduce the time required direction, and the stage of crop He has found a cost-effective way to to build the tunnel a second time from growth,” he said. “During initial fruit- produce good yields of high-quality 250 hours to about 200 hours. set—the most critical time—I look at tomatoes in the early and late periods the hourly forecast on the Internet. of the tomato season, when prices are Since Haygrove tunnels are not During that six-week period, I literally at their peak. And, by being in the designed to withstand more than a few baby-sit the tunnel.” marketplace in the early part of the inches of snow, they were a good season, he is able to continue selling choice for Cedar Meadow Farm as Like other high tunnels, multi-bay tomatoes from the field. Steve wasn’t looking for an over- units are ventilated manually, but wintering structure. He wanted to instead of rolling up the sides and However, Steve cautions growers who begin production after snowfall was ends, the plastic on a multi-bay is are considering a purchase of this kind no longer a threat, and finish the pushed up, and held in place by to do their homework. If winter season before winter. To prepare for adjusting the tension on the ropes that production is one of your goals, winter, he removes the sheets of hold the plastic down. During the choose another structure. If you have plastic, placing them in the gutter of early season, when days are warm and a particularly windy site, consider a every other bay, a job that takes about nights are cold, ventilation is time- different structure. But if you are 20 labor hours to complete. He wraps consuming. Steve estimates that looking for a three-season structure them in black plastic to prevent decay ventilation takes from 15 minutes to that is tractor-accessible and relatively from ultraviolet radiation. two hours of his time every day for inexpensive, the Haygrove may be a the first six weeks of the season. good choice for your farm.

11 – High Tunnels Case Study: Intervale Community Farm

ember-owned Intervale started using high tunnels in 1999 to flavor. ‘Jetstar’ is less resistant to Community Farm (ICF) is ensure a steady supply of tomatoes to Fulvia, though, so Andy continues to M located in the heart of his shareholders. look for others. ‘Big Beef' is a pretty Burlington, Vermont, on the site of good choice, but runs a bit larger than the city’s last dairy farm. It was ICF has a total of six tomato tunnels. Andy likes for the CSA. Andy’s trials started in 1990 as a not-for-profit Four are 14' x 96' units. Two measure of ‘Fabulous’ from Seedway looked Community Supported Agriculture 14' x 144', and have sides that are favorable, though the fruit are not (CSA), and currently has nearly 500 about 18 inches higher than in the quite as tasty as ‘Big Beef’ or members. Andy Jones has been the other four. The gothic-shaped ‘Jetstar.’ farm’s manager since 1994. Andy, structures were made by Ledgewood assistant farmer Becky Maden, and a Greenhouses in New Hampshire. Some other types of tomatoes— staff of seven seasonal employees Andy selected the structure for its heirlooms and other colors—are also produce 20 acres of vegetables, strength, snow-shedding design, and grown at the farm, but these tomatoes flowers, and berries for member economical cost, which was about represent no more than one-quarter of households. The farm is one of the $0.90 per square foot. the total. Popular heirlooms are oldest CSAs in Vermont, and is the ‘Cherokee Purple’ and ‘Rose d’Berne’ single largest. The frame cost between $1,200 and which is pink. Every year a few new $1,250, not including the roll-up yellow and orange cultivars are tried, The Intervale is a 1,500-acre flood- sides. The taller sidewalls added a but the perfect combo of size, yield, plain delta at the mouth of the couple hundred dollars to the purchase and flavor is still elusive. Winooski River, and is home to price but are well worth the price. In twelve other small farms, creating 2003, the four-year, six-mil Andy sows his first tomato seeds what Andy describes as a “collegial greenhouse plastic that Andy uses during the first week of March. He and supportive community of farmers costs about $350 for a 28' x 100' seeds into row trays, and then, about and entrepreneurs.” The farm sits on a piece. The total cost of the high two weeks later, pots into 4" square level, well-drained soil that is suited tunnel, including structural steel, cells. The first tomato transplants are to vegetable production. Although the wood for end-walls and sideboards, set out on May 1, about eight weeks weather at the Intervale is slightly hardware, and the labor to construct it, after seeding. moderated by Lake Champlain, the was approximately $2,000 for a 14' x growing season is still relatively short. 96' house. Andy calculates a yearly Each tunnel has four beds. Tomatoes It is considered a cold Zone 5 or a cost of $400 to own the 14' x 96' are planted in rows 42" on center, warm Zone 4, with the average last structure, basing this figure on a ten- except for the two inner rows, which frost on May 12, and first fall frost on year payback. However, the metal are just 34 to 36" apart since both October 1. tubing of the frames should last much rows are trellised overhead to the longer. Andy estimates that the wood ridgepole. For winter greens The farm’s produce is distributed for parts of the structure (hip boards, production, they divide each tunnel about 22 weeks, from mid-June to baseboards, and end walls) need into two outer beds 30" wide and two early November. Members visit the replacing every 10 years. inside beds 36" wide, with three one- farm each week during that period to foot wide aisles. pick up their shares and harvest their Andy seeks a nice mid-size (7 to 10 own flowers, herbs, peas, beans, ounce) red tomato for the bulk of the The beds are usually rototilled in the berries, and cherry tomatoes. The production. For the taller tunnels, spring, although when the residue is weekly share includes baby salad which are trellised overhead, ICF has not heavy, they may be hoed instead. greens, carrots, broccoli, cucumbers, been using the ‘Buffalo’ variety and is They add two to three cubic yards of and tomatoes, among other currently trialing replacement compost per tunnel (roughly 65 cubic vegetables. greenhouse cultivars that are as yards per acre) and other soil flavorful and productive. In the amendments as indicated by soil test Andy says that the field-grown tomato shorter tunnels, where the tomatoes results. season lasts five to six weeks—from are trellised with a basket weave early August through mid-September. method, the main red tomato has been In addition to the compost, they Because member surveys indicated ‘Jetstar.’ This cultivar has a beautiful generally apply 50 lbs. of greensand, a that tomatoes are favorite crops, Andy appearance, moderate size, and good little over 20 lbs. of azomite and, for

12 – High Tunnels calcium, about 25 lbs. of gypsum. By mid September, they generally An exception, however, is leaf mold, Often they spread a little nitrogen stop watering the tomatoes altogether. caused by the pathogen, Fulvia starter fertilizer at a rate equivalent to fulvum. This disease is particularly 30 lbs. N per acre to give the early Andy now uses determinate varieties problematic where temperatures and May planting a boost. Lately, they in the shorter tunnels so that their relative humidity inside the tunnel have been using a dehydrated chicken vines don’t overrun the structure. He have been high, chiefly in the late manure called Cheap Cheap from uses a stake-and-weave system, where summer and autumn. Basket weaving, North Country Organics as their early a stake is placed between every other though beneficial in many ways, nitrogen source. With a 4-3-3 tomato plant in the row. Andy finds inhibits air circulation and field analysis, this product provides a bit of that the effort of staking and stringing cultivars that are most suitable for soluble phosphorus and potassium as is rewarded by an increase in the basket weaving don’t have the Fulvia well. proportion of marketable fruit and by resistance that some of the greenhouse easier harvesting. He prunes his varieties have. The beds are covered with black tomatoes, removing all the suckers landscape fabric, each outfitted with a and leaving one leaf spur below the The tunnels are ventilated by means single drip irrigation line. The same first flower cluster. of roll-up sides. There are no gable fabric has been in use for seven end vents and the tunnels’ 8' x 4' growing seasons and appears to be In the taller houses Andy uses an doors (on one or both ends) are not going strong. A 15' x 100' piece costs overhead trellis, prunes each plant to a deliberately used to manage air about $100. single leader, and uses clips to hold movement. The chief management the tomato vine to the trellis. Andy activity associated with the tunnels is X-shaped holes cut about 4" x 4" in recommends taller structures because the time required for temperature and the landscape fabric allow for easy they offer more choices with respect ventilation management. Andy transplanting. He has also tried cutting to variety selection and because they estimates that during the “high longer slits, but the strands of fabric give better air circulation. The maintenance phase,” about a half an tend to impede rapid planting as they additional air volume also helps to hour per day is dedicated to pull free in later years. While burning keep temperatures up in cooler spring environmental management for the makes tidy holes, Andy does not like and winter conditions. six-house complex. Spring tomatoes burning plastic, and he and his crew are pollinated with Class ‘C’ found the razor-sharp edges of the Andy’s planting schedule reflects his bumblebee hives. Late crop tomatoes torch-made transplant holes to be desire to extend his outdoor field rely on wind through the rollup sides abrasive and objectionable. He said, production. Each year, about half the to set fruit. “250 holes per house, 6 houses a year, tunnels are planted early (from the 10 years per sheet of fabric…you get end of April to early May). These are Andy has been very pleased with his the idea.” intended for the first four weeks of the yields. His six tunnels, along with harvest season. These tunnels have about 800 field tomato plants on a Andy transplants one row of tomatoes back-up heating units that are only quarter acre, are enough to provide down the center of each bed, using a used during very cold nights. The each of his 500 members with 30 to 18" in-row spacing. This gives a plant other houses are planted in mid-to-late 40 pounds of tomatoes over a period population of about 250 plants per 14' June, and are harvested beginning at of eight to ten weeks. Harvest begins x 96' tunnel. the end of August and continuing in earnest in mid-July, and winds through the end of September. In down in late September, in time to Tomato irrigation is primarily between those picking windows are plant a crop of fall salad greens. Andy accomplished with 0.6 gal/hr drip line. the field tomatoes, if the weather estimates the cash value of the tomato At transplanting, they typically soak cooperates. crop at around $30,000 (17,500 the tunnel with an overnight watering. pounds at $1.75 per pound). After that, the plants automatically The tunnels have helped reduce insect receive about 25 to 30 minutes of pest and disease incidence in Andy’s Years of ICF member surveys have water per day. A battery-powered tomatoes. Insects in the tunnels have shown that tomatoes are always timer ($35 from the local hardware not been a problem, despite the within the top five most popular crops store) controls the watering so no one absence of any kind of rotation. and contribute one of the largest has to remember to water. Once the Diseases that were chronic problems percentages to the overall CSA share fruit begins to ripen, they reduce in the field, such as the leaf blights value. Therefore it has made sense to watering to around 15 minutes a day. caused by Septoria and Alternaria, are invest in high tunnels to ensure no longer a concern. success. Andy thinks the tunnels

13 – High Tunnels might also be suited to trellised begins increasing again, Andy says, crops intended for harvest January or cucumbers and red peppers, but he has development virtually stops, except later. settled on tomatoes because they are during particularly sunny days, and the crop most valued by his members. the crop temporarily enters a kind of To water their high tunnel greens, suspended animation. they set up Netafim DAN “With high tunnels, our members are microsprinklers (these sprinklers don’t pleased because we can provide them Andy’s goal is to have a succession of put out much water) and soak the with more and better tomatoes over a salad greens harvests throughout the houses for 24 to 48 hours prior to longer period of time,” said Andy. winter. Nevertheless, a single planting planting. After that, they water “And we are pleased because content date is sufficient. The high tunnel is overnight about once a week until members are likely to renew their essentially a winter warehouse of later fall. The lack of irrigation water memberships. Our financial stability salad greens. Once established, they during winter months is a problem at stems from repeat business—it’s far will be available for harvest ICF with its very sandy soil. Andy easier to make happy customers than throughout the winter, as long as they imagines that February and March to find new ones.” are not exposed to extreme cold. yields would be greater if irrigation were possible. Given the opportunity, To increase the return on his To help reduce the risk of freezing he supposes they would water once investment in high tunnels, Andy has injury, Andy covers the crop with a every three or four weeks during the begun using them to grow cold-hardy medium-weight row cover that he winter. greens offered as part of a winter CSA suspends over low wire hoops. In his share. This share also includes stored experience, the greens he grows are Andy has also used the farm’s heated squashes, cabbage, and root crops hardy down to about 21°F. So far, 30' x 96' greenhouse for winter greens from ICF, supplemented with Andy has not felt the need to add production. Even without products from other local farms, such supplemental heat. Nighttime supplemental heat, he saw as organic eggs, goat cheese, and temperatures inside the tunnel are significantly better greens growth in apples. generally 5 to 10°F warmer than the greenhouse than the high tunnels. outside temperatures, and the covers Andy suspects that the larger thermal The kales, mustards, Tatsoi, Mizuna, add another 5 to 10°F of warmth. As mass afforded by the greenhouse arugula, and spinach are on Andy’s heat radiates from the soil, it is structure provides a more consistent short-list of hardy greens. Though ICF trapped under the low cover, offering growing environment than the much has experimented with other hardy protection to the plant canopy. narrower hoop house frames. This greens such as Claytonia, Sylvetta suspicion is reinforced by the fact that arugula, Mache, and so forth, so far Andy direct-seeds his salad greens the taller hoop houses do better in the the standard field salad greens have with a single row Planet Junior seeder. winter than the shorter versions. outperformed them for ICF. He had previously used a six-row pinpoint seeder for all these crops The value of convenient mid-winter To prepare for the winter shares, except for spinach. He counts on just ventilation also has become apparent Andy removes the tomato vines, one harvest, but sometimes a second to Andy. He is currently examining twine, stakes, and plastic mulch by the cutting may be made in the early the feasibility and cost of adding a end of September. In his experience, a spring. By mid-February, when small exhaust fan and louver to each winter salad crop must be direct- daylight exceeds ten hours, the crop hoop house for winter use. Last seeded in early October to be shows signs of renewed growth. The winter, which was warmer than usual, successful. Crop growth will be slow mustard family crops do reasonably ICF had some disease problems in during the late fall because of the well through much of December, spinach that were largely a result of cooler temperatures and shorter day except for the kales which can thrive warmer, humid conditions. Andy has length. In unheated and unlit throughout the winter. Spinach is the found the roll-up sides to be structures, most crop growth must mid-winter standout, and ICF is somewhat impractical for winter use, occur before the end of November. considering quitting all other green when a tight seal is often desired After that period until the day length shortly after venting.

14 – High Tunnels Enterprise Budget for a Six-Month Tomato Crop in a 2,000 sq-ft High Tunnel at the Interval Community Farm

Fixed Costs Construction Costs Materials Labor Site prep (tractor time, labor) $60 $48 High tunnel layout $10 $48 Frame & construction $5,000 $576 Lumber, hardware, and labor $800 $384 Endwall finishing $250 $144 Water service $50 $12 Irrigation (valve, tape, water timer, header, fittings) $100 $32 Backup heater $225 Other -- weed mat $200 Other -- harvest containers $200 Subtotals $6,895 $1,244

Total Construction Costs $8,139

Fixed Costs High tunnel construction (divided by 15 years) $543 Interest (construction financed at 7% for 15 years) $285 Taxes, land, office expenses, fees $800 Total Fixed Costs $1,627

Total Fixed Costs (six-month tomato crop) $814

Variable Costs (six-month tomato crop) Materials and Machinery Plants $700 Fertilizer and compost $175 Irrigation supplies $10 Stakes, string, clips $200 Heater fuel $75 Bees for pollination $100 Poly covering (divided by 4 years) $200 Misc. supplies, repairs, maintenance $150 Subtotal $1,610 Labor Costs ($12/hr) Bed preparation and fertilization $144 Transplanting, laying drip tape and weed mat $144 Site mowing and weeding $144 Pruning & trellising $576 Harvesting, grading, packing $480 High tunnel clean-up $120 Annual maintenance $96 Environmental management $360 Subtotal $2,064

Total Variable Costs $3,674

Total Costs $4,488

Revenues* $8,750

Net Returns $4,262

*Revenues are based on a tomato yield of 3,500 lb per 14 X 144' high tunnel. The tomatoes are assigned a value of $2.50/lb, and revenues were $8,750.

15 – High Tunnels Case Study: Star Light Gardens

lmost half an acre of intensive was attractive to Ty who, as a visual feasible. David and Ty say they would production in five high artist, found working alone in her have opted for ridge vents if they were A tunnels (17,500 square feet) studio to be too isolating. more affordable. complements an acre of field grown salad crops and other vegetables at To build their first high tunnels, they In their first four tunnels, the Star Light Gardens, located one half took out a home equity loan. By Zemelskys experimented with two hour south of Hartford, Connecticut. Thanksgiving of that year, their son (a types of fans. Above the doors, each Mixed baby greens, mesclun, and landscaper) had prepared the site and of these tunnels has a louvered vent tomatoes as well as arugula, basil, and they had erected their first two high on one gable end and a big exhaust pea tendrils are currently David and tunnels. They remember the date— fan mounted at the other. A thermostat Ty Zemelsky’s main tunnel crops. April 9, 2000—of their very first triggers the louvers to open and let Close to year round sales of freshly greens harvest, from seeds sown in fresh air in. This automatically turns harvested produce from this micro- February. When June rolled around, on the fan. They set the thermostat at farm provide the couple with their with a small field planted outside and 80°F for winter greens. livelihood. Each had another career restaurants buying their produce, before they made a quick transition to David left his school psychologist job Horizontal airflow (HAF) fans are the farming in the late 1990s. for good. second type they had installed. This conventional greenhouse ventilation David always had a passion for Within two years, David and Ty had system is comprised of four window gardening. In the years before he and put up a total of four 30' x 96' high fans hung from the trusses, with one Ty started their own farm, David tunnels on a North-South axis. Next, pair blowing air up one side and the deepened his horticultural know-how they hired the local greenhouse other pair blowing it down the other by lending a hand to an aging friend fabricator to construct a 30' x 144' side. Their purpose is to keep air and long-time organic farmer. At the structure on an East-West axis, circulating inside, particularly on time, he did not imagine that pursuing making it their warmest and brightest cloudy winter days when the tunnels his avocation would enable him to tunnel. All are gothic style. are closed. After the Zemelskys quit his day job. stopped growing fall and winter Their first two high tunnels are lettuce (their mildew-prone crop), Listening to his friend’s tales of skinned with double layers of plastic they eagerly stopped running these winter growing pioneer inflated with a small blower fan. fans and significantly cut their high prompted the Zemelskys to make a Initially none of the tunnels had heat. electrical consumption. 500 mile round trip pilgrimage to After a few years, they decided to Coleman’s Four Season Farm on install a forced air oil furnace in one Ingredients of the Zemelskys’ salad Maine’s Penobscot peninsula in of these original tunnels to facilitate mix changes with the seasons and October 1999. Ty said, “We didn’t early tomato production. Ducts every year they experiment with new even know what questions to ask.” transport hot air to an adjacent tunnel. varieties. Their hardier, sturdier They bought Coleman’s Winter They have no inclination, however, to winter mix contains about eight Harvest Manual and Ty, who put heat in their other three tunnels. different kinds of cold-hardy brassicas describes herself at the “instigator,” (including ‘Siberian’ and ‘Dino’ kale), decided that there was no reason they The Zemelskys chose high tunnel and various Asian greens such as couldn’t start their own business using design options that maximize passive Tatsoi and Mizuna. Claytonia—which this model. ventilation. They set 30" roll up sides thrives in cold, low light conditions— about 2' above ground level to protect is a winter favorite. Arugula accounts With their children grown, the young plants from cold blasts of air. for as much as 30% of their sales. Pea Zemelskys had been exploring ways Directly below the roll-up is the high tendrils are another important cool to be self-employed together. They tunnel baseboard. Plastic film weather crop. Some of their seed were about 50 years old and fit covering the tunnel below the comes from High Mowing, a small enough to be running marathons. baseboard is buried in a trough in the Vermont seed house that only sells They wanted to find “good honest ground. On each high tunnel, both open-pollinated, organic seeds. Wild work” that was compatible with their gable ends have large doors that fully Seed in Philomath, Oregon is values and provided a reasonable open. Under cold winter conditions, the source for chervil and mixed livelihood. A home-based enterprise these passive venting systems are not mustards they like called, ‘Morton’s

16 – High Tunnels Mild Mustard Mix.’ Johnny’s Over the years, the Zemelskys have different watering methods. For their Selected Seeds is another source. found weeds to be quite challenging. summer crops like tomatoes and Weeds slow harvest and compete with peppers, drip irrigation helps conserve Timing is very important for winter the crops. Certain tenacious cool their extremely limited water supply. production since the growth rate of season weeds, like chickweed, have With the aid of electronic timers, they crops decreases to almost a standstill been very difficult to overcome. Stale irrigate three times a day—in the in the weeks leading up to winter seed bedding followed by flaming is middle of the night and early morning solstice. To work around this cycle, proving to be the best prevention for hours—in order to load up the soil the Zemelskys have learned to sow weed proliferation. After preparing with water before it gets too hot. greens from early September through the seedbed, David irrigates and, October 7 for winter harvest in their when the weeds emerge, he cooks With their greens seeded in blocks location. They start slower growing them with a propane backpack flamer. rather than rows, drip irrigation is not crops like spinach, chard, and beet David is learning to leave two weeks feasible. David is slowly converting greens earliest. For spring harvest, between getting the beds ready and his overhead irrigation to a product they have planted late into November planting the crop to allow time for this called “Ein Doers” that is sold by and in February. With the exception technique. various dealers. Four rows cover a 30' of tomatoes, all of their high tunnel wide tunnel. He also uses a crops are direct seeded. After using a four-row pinpoint seeder conventional rotating sprinkler, for several years, David graduated to a mounted on a tripod, and another Intensive production and double or newer six-row model that has built-in conventional sprinkler that goes back triple cropping requires ample nutrient rollers. He said the six-row seeder is and forth. availability. Before fall planting, an improved model that is more David applies an inch of a purchased forgiving than the four-row one. He After sowing, the late plantings are certified organic leaf-based compost. recommends a plastic cover over the protected with a medium-weight, spun In the spring, he adds more compost seed trays for keeping soil from polyester row cover to assist the crop as well as some organic fertilizer into kicking into each bin, and Johnny’s in germination. This microclimate the tomato transplant holes. The incorporated that suggestion. He said, warms the soil 2 to 3°F. Sometimes Zemselskys also make their own “At first it didn’t seed well, but the their plantings under the row cover compost by windrowing leaves from company got the kinks out of it, for experience some dieback. When the local landscapers. Since these the most part.” seedlings reach a certain size, the row composts are low in nitrogen, David cover is suspended over wire hoops supplements them with a purchased With any of the pinpoint seeders, pressed into the ground. The hoops fertilizer product from North Country monitoring the operation of the seeder prevent the row cover from chafing Organics and alfalfa meal for extra is critical in David’s experience. He the fragile leaves and freezing onto nitrogen content. They test the soil makes sure the shaft is turning and the the plants. This structure also keeps periodically as required by their belt has not jumped onto a different condensation off the plants. organic certification agency. pulley as this determines how much seed is sown. The Zemelskys begin their high tunnel David used to roto-till the soil but he greens harvest in November and has discontinued that practice because To achieve the intensive production December. For the first few years, he feels it damages soil structure and he aims for, David prefers to grow his they harvested throughout the winter brings up weed seeds. Instead, he uses greens in blocks rather than rows. without a break. They have since shallow tillage to prepare the planting Rows allow for cultivation with a hoe, stopped selling greens in January. By beds. He is experimenting with a whereas blocks do not. He explained winter solstice, short day length and small power harrow, a tool that does that seeding in blocks requires low light have considerably reduced not invert the soil. Alternatively, he successful implementation of stale plant growth, so they take a needed uses hand tools for soil preparation: a seed bedding to reduce the weed seed break while they wait for more re- saddle hoe to remove debris and old bank. If an area is too weedy, he can growth to occur. By early February, plants, a wheel hoe with a cultivator still use his six-row pinpoint seeder, with the sun higher in the sky and the attachment, and a broad fork. Before filling only two of the six hoppers in light intensifying, they resume planting, he rakes the seedbed and order to skip two rows for every row harvesting and also reseed some beds firms up the top layer of soil with a he seeds. as necessary to ensure a strong March mesh roller. and April harvest. Like others with a similar mix of crops, the Zemelskys use two

17 – High Tunnels Harvesting salad mixes constitutes a their markets through Thanksgiving, The Zemelskys make a wire trellis for major portion of their labor. The and then start harvesting in the high the tomatoes using the support dense, good quality crops at Star Light tunnels. The system appears to be structure of the high tunnel. They Gardens can be cut with more speed working, though he will need to tinker typically use double leaders, pruning and the Zemelskys can cut almost 30 with crop timing in both of these each plant to two main stems. The pounds per hour, compared to 20 growing environments. rows run the length of the tunnels, pounds an hour in a more average with nine rows fitting their 30' width, stand. Ty used to be the main cutter Pea tendrils are a money-making crop though David is considering growing but an old back injury was aggravated that the Zemelskys grow wherever fewer rows. In order to get earlier by all the bending. Now David does they can fit it in, such as around the tomatoes, they may heat one tunnel to most of the harvesting, with the aid of colder edges of their high tunnels and 60°F. This year, they began a harvest cutter and a net bag in a between the rows of tomato plants experimenting with grafting tomatoes. laundry basket. until they fill out. While pea plants They specialize in heirloom varieties cannot handle freezing the way hardy for their discerning customers and For the greens harvest, they cut with Brassicas and Claytonia can, they do also grow some indeterminate good, small, light-weight kitchen well in cool fall and late winter greenhouse cultivars. Chefs order knives into nylon nets (from a fishing conditions. tomatoes by color. supply company) placed in laundry baskets. They wash the greens in the A pound of ‘Dwarf Grey Sugar Pea’ Star Light Gardens has been very net bags and then run the bag through seed costs $1.30 and yields about five successful in marketing. Restaurants the spin cycle of a standard washing pounds of tendrils on 5" high pea were originally the mainstay of their machine. They mix the greens to their plants. The Zemelskys plant 10 to 15 sales, but after several years of standards or for special orders in a pounds of seed per week. David and farming, they added farmers’ markets home-made mixer. If a batch of salad Ty sell the pea tendrils alone for $13 a and the Yale University Sustainable mix grows too big, they sell it as pound. Occasionally they add them to Dining Program to their customer braising mix. salad mix for more weight. David base. says, “Pea tendril pesto has regular A couple of winters ago, the basil pesto beat, and so much earlier!” Connecticut has few farmers in Zemelskys ceased trying to grow relation to its population, and organic, lettuce in the winter. David says that They have also added micro-greens to fresh, and unique produce is in great lettuces are too susceptible to their marketing mix. They have found demand. The Zemelskys consciously powdery mildew under low light and that these greens have already helped aim to differentiate their produce from high humidity conditions to be worth their bottom line. generic products, and they trial new the trouble of growing in winter. They varieties every year. They have been also grow too slowly after their Depending upon how early their field able to maintain their wholesale price August planting, requiring a full week dries out, they transition to harvesting for salad mix at $8 per pound. David longer than Brassicas, and are not field-grown greens sometime in April said, “There is no competing product. nearly as cold hardy. Since Ty and or early May. The transition between What you get from California does David market their produce as local high tunnel and field production can not compare with what we have.” and seasonal, their customers readily be a challenge. They have attempted accepted their explanation, without to overwinter field greens in low The Zemelskys enjoy a nice “batting an eye.” Always tunnels, but the results have not been relationship with chefs and find it experimenting, they may try seeding consistent. advantageous at their scale not to rely lettuce in February for the spring on a distributor or purveyor. They get harvest. Initially the Zemelskys only produced new accounts by visiting restaurants salad greens in the tunnels, leaving or when chefs find them through the In 2006, a visit to Bryan O’Hara’s low them vacant in the summer. In their Northeast tunnels in eastern Connecticut sparked fourth year, they added tomatoes and Association of Connecticut (NOFA- a fundamental change in Star Light basil. Tomato transplants go into the CT). “Chefs are movable people,” Gardens’ cropping philosophy. (See high tunnels from March until early said David, “We can gain or lose section on Low Tunnels, page 38.) In April and the tomato harvest lasts accounts when they change jobs.” mid- and late September that year, from June through early October. David planted lettuce outside in low They must quickly pull out the tomato Currently they wholesale to about two tunnels. He says his goal is to have plants in time to reseed the tunnels to dozen restaurants. Their weekly enough field-grown lettuce to supply fall greens. delivery route also includes four

18 – High Tunnels stores (including a family-owned IGA Enterprise Budget for a Six-Month Brassica Greens Crop in an Unheated and natural foods stores). 3,000 sq-ft High Tunnel at Starlight Gardens

They first tried selling at a farmers’ Fixed Costs market in 2004, when the founder and Construction Costs Materials Labor manager of a new market in New Site preparation, bulldozer $1,500 Haven recruited them. A couple of High tunnel construction $600 years later, they joined another High tunnel frame $3,000 farmers’ market an hour away, which Lumber and hardware $400 began when the sponsoring Endwall finishing Water and electrical service $311 $100 organization of the first market Irrigation $150 expanded its reach. Farmers’ markets Exhaust fan and louvered vent $750 have been lucrative and sociable for Bed preparation $150 the Zemelskys, and have also resulted Other (horizontal air flow fans) $330 in contacts with chefs and other Subtotals $5,091 $2,200 buyers. Total Construction Costs $7,291 The Zemelskys have also been selling Fixed Costs a significant amount of their High tunnel construction (divided by 15 years) $486 production to Yale University since Interest (construction financed at 7% for 15 years) $255 2004 when it began piloting local Taxes, land, office expenses, fees $225 food in one dining hall. The Total Fixed Costs $966 University is willing to pay 50% more than the going rate to obtain locally Total Fixed Costs (six-month winter season) $483 grown, preferably organic, food. Yale buys a third to a half of their salad Variable Costs (six-month winter season) greens during the late fall and early Materials and Machinery Cost winter. Seeds $46 Fertilizer, lime and compost $78 Plastic mulch and row cover $75 Heater fuel and electricity $25 Beneficials and pesticides $10 High tunnel poly cover (1/2 year) $110 Delivery costs $175 Subtotal $519

Labor Costs ($20/hr) Poly cover installation and removal $75 Bed preparation and fertilization $160 Planting $60 Irrigating and managing row cover $20 Harvesting $750 Washing and packing $300 Sales and delivery $420 Subtotal $1,785

Total Variable Costs $2,304

Total Costs $2,787

Revenues* $6,000

Net Returns $3,213

*Revenues are based on a Brassica greens yield of 0.25 lb/sq-ft or a total of 750 lb per cutting in the Zemelsky's 3000 sq-ft high tunnel. The greens were sold at $8/lb. Arugula, which sells for $11/lb and is not as cold resistant as some other brassicas, was not included in this accounting.

19 – High Tunnels Case Study: Slack Hollow Farm

wenty-five years ago, Seth Seth and Martha have been growing the winter, taking cuttings on a given Jacobs and Martha Johnson spinach during the winter for four section about 60 days apart, T started Slack Hollow Farm in years and the system they have depending on the amount and length the Taconic foothills in Argyle, New developed works well for them. of sunshine and the temperature. For York, located a little over an hour plants harvested on December 20, the Northeast of Albany. In their early As a certified organic farm, compost shortest day of the year, a second years, they did all their fieldwork with has been the basis of Slack Hollow harvest will be ready during the last horses and depended heavily on hand Farm’s fertility program. In the past, week of February. Production all but tools. Today, with 15 acres in they added farm-made manure-based ceases between December 20 and vegetable production, the farm claims compost at the rate of 10 tons per acre January 30, so spinach is stockpiled three small tractors, numerous by running their manure spreader for that period. A bed cut at the end of implements, a box truck, a down the middle of the tunnel. New February will be ready for another greenhouse, and two high tunnels. organic regulations require long cutting in early April. At this point, Seth and Martha grow a wide range of intervals before harvest, so now they they take their last harvest, so they vegetables and salad greens that they only apply compost in April, prior to can renovate the tunnel in preparation sell at two substantial producer-only planting the tomato crop. (A foliar for tomato planting. farmers’ markets and to wholesale spray of Epsom salts for magnesium accounts. Their primary high tunnel on tomatoes is their only other They cut most of the spinach plant, crops are spinach and other salad nutrient input.) leaving one or two new leaves behind, greens, produced in the late fall harvesting by holding the prostrate through spring, and tomatoes and After removing the tomato vines and leaves up with one hand, and cutting basil, grown in the warmer months. trellises at the end of September, they with the other. roto-till the soil with a tractor- The first of their two tunnels is a 21' x mounted tiller to prepare a good The first cutting of the winter spinach 120' gothic-shaped structure seedbed. Time permitting, they will is of the highest quality, and the sugar manufactured by Ledgewood flame-weed before seeding, but even levels seem to be higher. Customers Greenhouses. They built it in 1995 when they can’t get to it, weeds notice that it is sweeter than outdoor from a kit and estimate that it cost appear to be under control. Martha in season. Leaf quality goes down between $6,000 and $8,000. This direct-seeds the spinach using a one- with each cutting, but the taste relatively simple tunnel does not have row Planet Junior seeder, producing remains unsurpassed. And it is still electricity, heat, or fans, and uses roll- remarkably straight rows. She aims superior to what is found in grocery up sides for ventilation. It has an East- for 12 to 16 seeds per foot, with rows stores at that time of year. West orientation. In this structure, four inches apart. they utilize a two-crop rotation. They Their markets for winter spinach and grow tomatoes and basil from early ‘Space’ is the variety they prefer other greens include a large food co- May through late September or early because of its leaf type, eating op in Albany, with which they have October, and spinach from mid- qualities, yield, and cold-hardiness. had a very long relationship, and a October through early April. Spinach is very winter-hardy. “No large farmers’ market that operates temperature can kill it,” Seth says. throughout the winter. If they expand Seth and Martha stopped growing their winter production, they would tomatoes in the field about ten years Protecting the spinach plants with add more markets, or perhaps start a ago because the yield and quality of floating row cover is essential. They winter CSA. Currently, retail spinach their tunnel-raised tomatoes is so use up to four layers of mid-weight prices are in the range of $10 to 12 per much better. Their farm in Argyle is spun polyester row cover to buffer the pound. They expect to harvest a total in Zone 4, providing relatively little crop from sub zero temperatures. The of 1,000 to 1,500 pounds of spinach time to for a field-raised crop to aim is to manage the freezing of the from the unheated 21' x 120' tunnel, develop. Also disease pressure in crop and soil during very cold periods, generating sales of $10,000 to field-grown tomatoes is high, as this would interfere with or prevent $15,000 during the winter. reducing marketable yields and harvest. profitability. In 2004, Seth and Martha constructed In the unheated tunnel, they get at a second high tunnel which some least three harvests of spinach during might consider more a soil-based

20 – High Tunnels greenhouse. Its North-South time of year when competition from “Production far surpassed the orientation was determined by their other local producers is lower.” unheated high tunnel,” Seth said. existing field layout. The 30' x 120' They have been using their new gothic-shaped structure was made by tunnel to grow a variety of cold-hardy Even with the in-ground heating Rimol, a company that provides greens including arugula, Tatsoi, system, row cover remains an valuable technical assistance. Unlike Mizuna, kale, radishes, turnips, beets, essential element of winter growing at their first high tunnel, they had this Swiss chard, and Bok Choy, as well as Slack Hollow Farm. In the heated one built by professional contractors. spinach. Some of these crops are high tunnel, daily covering and It cost about $25,000 to build, seeded with a pinpoint seeder. uncovering with medium-weight including the structural steel, the Between the lateral beds (not raised) floating row cover is required to heating and venting systems, cover wooden boards focus foot traffic in prevent overheating during the day. materials, and labor. very narrow paths. (They grow the To streamline the application and tomato crop in rows running the long removal of the row cover, this winter For ventilation, they outfitted the way.) They use the same production they plan to construct a hand-cranked structure with thermostatically techniques here as in the unheated roll-across covering system within the controlled automatic roll-up side tunnel as well as the same general high tunnel. (See inner coverings curtains and gable-end vents. These rotation. The addition of heat in this section, page 52.) features cost only a few hundred structure gives them more flexibility dollars more than a big exhaust fan with planting dates. At Slack Hollow Farm, the decision to and there is no power bill. Four equip a new high tunnel with ground standard greenhouse fans improve This new heated high tunnel has heat was intuitive. (See heating interior air circulation during warm benefited their spinach crop in several section, page 49.) Seth felt that for a weather and for fall germination. ways. While growing winter spinach tunnel covered with a single layer of Access is provided by large tractor in the original high tunnel, Seth and poly, such a in-ground heating system doors and, in winter, by a small Martha found that they could not would be significantly less expensive people door that opens inward so harvest early in the morning or during to run than heating the air. snow shoveling or plowing is not very cold days because the leaves required. would be frozen and quite wilted. The Seth and Martha have always used a addition of a small amount of ground single layer of plastic because they They covered the structure with a heat enables them to harvest spinach believe it has a smaller environmental single layer of plastic. On the end- during these cold periods. footprint or impact than two layers. walls and roll-ups they used a woven (For a different view, see Single vs. poly with 90% light transmission During a very high wind event in late Double Layer in Selecting Your which is much more durable and long- February 2006, they lost the plastic on Structure section, page 31.) It lasting than normal greenhouse film. their older high tunnel. The plastic transmits more light, results in half as They opted for extra-heavy bows film on this house needed replacing much plastic to dispose of, and averts spaced 5' on center, rather than the and the pine hip boards had rotted, the need for electricity to power an standard 4' spacing because the cost Seth noted. (Now all wooden parts in inflator blower. It is less resource- was lower. In-ground heat tubes Slack Hollow Farm high tunnels are intensive to use lightweight row circulate hot water to warm the soil made of Eastern white cedar.) The covers inside—which lasts for many and root zone. loss of the plastic occurred right after years. Seth stressed that they do not they had finished the first cutting of use high tunnels to grow a warm Several other growers now produce their winter spinach. This crop was weather crop out of season. They also spinach for winter farmers’ markets in lost to cold burning. do not use plastic mulch. their area, and competition has increased. To take full advantage of At the same time, two beds of spinach Seth estimates that a quarter to a third their winter marketing opportunities planted around December 15 were of the farm’s revenues come from and to more fully satisfy their maturing in the new, ground-heated their two high tunnels. He expects that customers, they decided to expand tunnel. “We got astounding yields,” the new (more costly) tunnel will pay their crop mix to include a range of said Seth. They cut these spinach beds for itself within two to three years. It less hardy salad greens. Building a on alternate weeks from the end of is very inexpensive to operate, new structure has made this diversity February until the last week in April requires no machinery except for more possible. Seth said, “We would and were able to supply their farmers’ tractor tillage twice a year, and takes like to increase production during a market from a much smaller planting. only about 12 hours per week of labor, yet produces very high yields.

21 – High Tunnels He anticipates $25 to $30 in sales Enterprise Budget for Winter Spinach Crop in an Unheated 2,500 sq-ft High per square foot. Tunnel at Slack Hollow Farm

Seth and Martha attribute much of Fixed Costs their initial interest in winter Construction Costs Materials Labor production to their desire to offer Site preparation, bulldozer $1,000 year-round employment to their High tunnel construction $2,100 farm manager, Colleen Converse. High tunnel frame $5,000 She is, in turn, responsible for most Lumber and hardware $500 of the winter harvesting and Endwall finishing $400 Water service $850 marketing. Irrigation $700 Bed preparation $240 “Our expansion into winter Subtotals $6,840 $3,950 production has been employee- driven,” Seth said. They are able to Total Construction Costs $10,790 travel in the winter because the Fixed Costs manager can handle the farm, and High tunnel construction (divided by 15 years) $719 they can also cut back in summer by Interest (construction financed at 7% for 15 years) $378 placing more emphasis on winter Taxes, land, office expenses, fees $1,377 markets. And year-round high tunnel production has also evened out the Total Fixed Costs $2,474 farm’s income. Total Fixed Costs (six-month winter season) $1,237

Seth and Martha like tunnels so Variable Costs (six-month winter season) much that they actually have a third Materials and Machinery Cost tunnel, 30' x 48', that they use as Seeds $50 their washing and packing shed. Compost $200 With the wash station end covered Irrigation supplies $50 with three layers of shade cloth in Row Cover $100 the warmer months, it is comfortable Poly covering (divided by 4 years) $90 all summer, and far more pleasant Packaging $30 than a dark barn. An added benefit is Delivery costs $560 no property taxes as assessed on this Subtotal $1,080 temporary structure. Labor Costs Bed preparation and fertilization $500 Seeding $48 Irrigating $100 Harvesting, grading, packing $1,500 Sales and delivery $1,500 High tunnel clean-up $100 Subtotal $3,748

Total Variable Costs $4,828

Total Costs $6,065

Revenues* $12,000

Net Returns $5,935

*Revenues are based on a spinach yield of 1,000 lb in a 21 X 120' high tunnel. The spinach was sold at $12/lb. Yields were reduced this season because a severe storm damaged the plastic cover. Revenues the previous year were $15,500 on yields of 1,550 lb and a selling price of $10/lb.

22 – High Tunnels High Tunnels and Marketing

ne of the primary reasons for finite amount of one product, a farmer Farmers’ Markets adding high tunnels to a farm can boost the food dollars spent by With minimal investment, farmers’ O is to increase marketing each buyer by offering more products. markets give farmers the opportunity opportunities. High tunnels enable Most direct marketers raise a variety to represent their farms and their growers to extend their marketing of crops during the growing season, products directly to the public. Good season. And because crops grown in and this can also be an effective farmers’ markets can be very high tunnels are usually of better strategy during the extended season. competitive marketplaces; however, quality, they usually command a they also gather together far more higher price and attract quality- For direct sellers, good signage, a shoppers for a compressed period of conscious shoppers. friendly and positive demeanor, and time than most individual farm stands. attractive product presentation will Successful farmers’ market vendors Producing a crop in a high tunnel is probably be adequate for creating an develop relationships with their typically more costly than growing it effective image. Home-grown customers. They establish loyal in the field, due to the structure’s promotions that take a little time but followers who are not distracted by capital costs and increased manual cost little or nothing can also help lower prices offered by other farmers labor requirements. On the other hand, create a buzz. Farmers can pitch their at peak harvest. when calculating the cost per pound stories to the media with press or bunch produced, high tunnels often releases or phone calls suggesting The competition inherent in come out ahead. Depending upon the why they are of interest. Writing a successful markets also speeds up the year and the crop, high tunnel yields newspaper column or getting a gig as spread of appropriate innovations like tend to be significantly higher than a radio show guest will also increase high tunnel production methods. With those for field production. The more public exposure. A public open house shoppers comparing the various controlled environment favors or tour for chefs are other means to sellers, willingness to learn and production quantity and quality. And make an impression on potential or flexibility to change are important when outdoor yields are severely current customers. attributes for farmers whose primary impacted by weather, pests, or other outlet is the farmers’ market. Seth factors, the comparison can be Packaging, labeling, websites, Jacobs has tried to position Slack particularly striking. brochures, ads, or other forms of Hollow Farm ahead of the curve. He branding may play a role in adding was the first in his market to grow Since the investments in high tunnel value, depending on the market outlet. large quantities of spinach all winter crops are greater, it makes sense for Any of these items may be helpful in in an unheated high tunnel. As other farmers to maximize the returns on the right situation. For example, a farmers adopted this practice, he high tunnel crops through a deliberate brochure is indispensable for CSA anticipated the next opportunity by choice of marketing strategies. Small farmers like Andy Jones in recruiting constructing a ground-heated tunnel to farmers often find direct marketing to members annually. Steve Groff expand and diversify his winter be essential, whether through farmers’ belongs to a grower co-op selling production. markets, farm stands, Community tomatoes and other crops to Supported Agriculture (CSA), and supermarket chains. A life-size cut- Taking Initiative to Extend even restaurant sales. Out-of-season out of Steve for display in the the Farmers’ Market production can pose significant supermarkets helped create demand Season challenges for marketing but it can for the group’s produce. As When farmers decide to use high also offer tremendous potential for wholesalers with 50 acres of high- tunnels to lengthen their harvest, they creating a profitable niche. value crops in production, the may not find a ready market awaiting Cramers can justify having a couple them. For instance, farmers who rely Boosting Value of websites where buyers can view on mid-season farmers’ markets may There are many ways to enhance the their flowers and learn about the seed have no outlet in early to mid- spring, value of production. When direct varieties they sell. For most small- late fall, or throughout the winter. marketing at farmers’ markets or to scale growers, high expenditures on a Without a good market outlet, there is chefs or small retailers, product lot of costly professional marketing no point in extending the season. diversity can enhance sales and put a materials are usually not warranted. farm in a preferred position. Since an Waiting for a market to appear is not individual customer will only use a practical. Instead, many farmers are

23 – High Tunnels taking initiative to develop or pick-your-own depends on a farm’s harvest, and will guarantee production strengthen markets to serve their location, the temperament of the farm even in a cold year. By avoiding needs. Farmers need not organize operator and farm family, and the precipitation and associated disease, markets single-handedly. Some of the capacity of the farm to accommodate high tunnels will often keep the crop best farmers’ markets are joint large numbers of customers and their going longer. In a rainy year, high projects of the farmer members and vehicles. Another consideration is the tunnel tomatoes usually significantly community advocates or enthusiasts. timing of the harvest season for a outperform field tomatoes. All of Farmers generally do need to stay particular type of fruit. Even when Andy Jones’ high tunnel production involved to ensure the market will fully vented, the temperature in single goes to his CSA members. Having a continue to work for them. bay high tunnels can become stifling consistent, high quality tomato crop in warm weather. helps keep Andy’s members happy One of the most promising strategies and coming back year after year. for farmers growing in the winter is Ed Weaver has found the climate starting an indoor winter farmers’ protection offered by his multi-bay Starting the CSA harvest earlier in the market. With proper planning and high tunnels to be attractive to his season or extending it later into the publicity, these new markets are pick-your-own fruit customers. The fall can also be achieved with high finding receptive audiences. Our quality of his sweet cherries is much tunnels. A longer season may well region now boasts at least four weekly improved, and even in inclement allow the farmer to command a higher winter markets, all started between weather, customers can come and price per share. A CSA farmer might 2002 and 2006. Fresh spinach, harvest protected from the weather. also use high tunnels to increase the brassicas, salad mix, and sometimes Due to the potential for spreading diversity of produce at the growing kale and chard are popular winter disease, pickers need to stay out of season’s start, even in a wet, cold items, and unless there is a large plantings when leaves and fruit are spring. All of these uses can help a producer in attendance, greens usually wet, even though rain may have CSA farm differentiate itself and sell out early in the market day. ceased. Because of these factors, high attract a loyal membership. tunnels enhance his customer base. Some farmers’ markets only run from Some farmers have organized winter mid-June through September. Such a Community Supported CSAs using high tunnels to produce short time frame is not conducive to Agriculture (CSA) greens. Winter CSAs can be as simple the creative use of high tunnels. For Instead of increased profit, the most or complex as the farmers wish. In regular farmers’ markets to start important benefit for the Community Wisconsin, a farmer started a stand- earlier in the spring or continue later Supported Agriculture farmer’s alone spinach share. He delivered into the fall, farmers must have livelihood may be risk mitigation. A spinach every couple weeks to appealing foods and other products to CSA farmer might not be able to Madison customers over the course of sell at these times. isolate the actual economic return the long cold winter. from a high tunnel since CSA A farmers’ market will not attract a members pay a lump sum for their In a more typical winter CSA, fresh critical mass of shoppers if spring share of the entire harvest. salad ingredients like high tunnel- greens are the only product for sale. grown spinach, brassicas, and even Vegetable farmers who are extending CSA members agree to share the lettuces complement storage the season might want to recruit financial risks with the farmer when vegetables like carrots, onions, beets, farmers who sell meats, poultry, they purchase a share in advance. It is parsnips, rutabagas, and winter cheeses, and other animal products, as in the interest of the CSA farmer to squashes. Winter CSAs tend to well as bakers and processed and minimize the production risks provide vegetables to their members prepared food makers to create inherent in agriculture and deliver the less frequently than growing season diversity and interest at a market. vegetables the members expect. CSAs. Biweekly or monthly deliveries Otherwise members may become from December through March are Pick-Your-Own disgruntled and the future of the CSA typical. Under the right circumstances, fruit may be jeopardized. grown in high tunnels can be an ideal A winter CSA need not be very crop for a pick your own operation. For example, CSA farmers in northern demanding of the farmer’s time. Of the fruit with which we are climates often use high tunnels to Providing off-season cash flow may familiar, fall raspberries and sweet ensure an adequate and sustained give winter CSAs value beyond the cherries seem to be especially good tomato crop. The added warmth of a relatively low income they bring in. candidates. The appropriateness of high tunnel may permit an earlier Another benefit of a winter CSA is

24 – High Tunnels allowing the farmer to amortize the The fact that such varieties may be high quality flowers they grow in their capital costs of the structure over less productive, don’t travel or store tunnels help them keep their multiple crops per year. well, or may be more delicate makes customers all season long. them less attractive for many farmers, Some CSAs are collaborations among but these characteristics also open up Some buyers are interested in two or more farmers. Some CSA a niche for small farmers who depend purchasing from farms in the region farmers are not interested in on direct marketing. Since these as a way to gain their own customers’ continuing production into the winter, finicky crops are not easily mass loyalty. For instance, Hannaford, a but have the ability to grow sufficient marketed, they have not been Maine-based grocery chain, recently storage crops to serve a CSA. A high embraced by supermarket chains or stepped up its locally grown program tunnel farmer who grows greens produce distributors. Specialty stores with the hope of attracting more during the winter could join forces and independent restaurants can use farmer suppliers and capitalizing on with such a farmer. This sort of CSA these varieties to distinguish their efforts with a customer partnership presents a direct sales themselves from chains by offering campaign. opportunity for a high tunnel grower these kinds of specialty vegetables. in areas where there are no winter A group of Lancaster County growers, farmers’ markets. Wholesaling including Steve Groff, have developed Effective wholesaling requires a wholesaling relationship with a Selling Directly to appropriate volumes of consistent regional supermarket chain in Restaurants and products. The task of the wholesaler is Philadelphia and its suburbs. High Specialty Stores finding customers who appreciate tunnels gave the group an edge in To gain acceptance with chefs and what they have to offer. In good dealing with this buyer. The specialty stores, farmers find that wholesale situations, quality matters, Haygroves afford more consistent interesting, superior tasting and exotic and high tunnels can help guarantee production and higher quality, two varieties are a real draw. Careful the desired quality. Getting a jump on critical factors for supermarkets that variety selection also “adds value,” the season and providing reliable are staking their future on excellence entitling the producer to higher prices. delivery and service are other in their produce departments. In The Zemelskys have maintained attributes that create enduring addition, the group is able to supply strong prices for their tomatoes with relationships with wholesale tomatoes beginning early in the an upscale chef clientele by growing customers. Early production gets spring, and extending late into the fall, heirloom tomato varieties. Cramer’s Posie Patch in the door with long after field production in the brokers who would otherwise look region has been shut down by frost elsewhere for their suppliers. And the and disease pressure.

25 – High Tunnels Site Considerations

t is a good idea to give careful accessible to fuel delivery vehicles, plants. Avoid cold pockets (i.e., the consideration to where a high and a fuel storage site should be bottom of a hill) and areas of Itunnel will be built. Success with identified. turbulence from adjacent hills or tree the structure is highly dependent on lines. its location. The high tunnel should be Tunnel Access and Room conveniently accessible, where water for Expansion Good high tunnels are sturdier than and electricity (if desired) can be High tunnels are relatively labor- they look. But a constant pounding supplied without excessive cost. A intensive structures and require and shaking from the wind can be well-drained site is essential, and the frequent access. In most situations, hard on a structure (not to mention a site should be graded to divert water. there is an advantage to locating high farmer’s nerves). Orienting the gable The site should offer full sun and tunnels close to the farmhouse and end to face the prevailing wind helps protection from the wind. established work patterns. Truck and limit the structure’s exposure. A tractor access is essential for moving windbreak is a good idea, especially Check local zoning ordinances and product and supplies in and out. for winter growing, as long as it permit requirements before you Proximity to the washing area, doesn’t affect sun exposure. proceed. Under most local zoning packing shed, and processing and ordinances, high tunnels are viewed as distribution area will simplify the Water Movement and “temporary” structures that do not operation. Drainage require a building permit. Similarly in High tunnels are most successful most jurisdictions, high tunnels are When considering where to locate when they are built on well-drained not assessed as a property your first high tunnel, keep in mind sites. Removing excess water from improvement and therefore are not that you may want to add more around the high tunnel is absolutely taxed. tunnels in the future. As one grower necessary. Run-off from a high tunnel put it, “High tunnels seem to like roof and from rain and melting snow Utilities company.” Make sure that your layout can be significant. An inch of rain Clean water that is free of sediment provides a logical plan for expansion, falling on a 30' x 96' house, for and chemical contamination must be while also accommodating farm example, works out to be 0.6 gallons reliably available in sufficient volume traffic and snow removal. per square foot, or 1,728 gallons over throughout the year—or at least the entire structure. This water and during those months when plants will With his array of six 14' wide high ground water should be diverted by a be growing. “Dirty” water may spread tunnels, Andy Jones suggests placing swale around the high tunnel. If there pathogens, blocks emitters in drip tunnels as far apart as they are wide. is uphill runoff, it is wise to divert this irrigation tape, and can even stain the Ted Blomgren suggests leaving water before it reaches the high high tunnel’s poly covering. alleyways that are at least as wide as tunnel. Ideally, the tunnel should be at the high tunnel is tall to prevent the least a foot above grade of the land Electricity is not a requirement for shadow from one structure from around it. A high tunnel water plan high tunnels as they are strictly falling on the adjacent structure. should be designed for the worst-case defined. Most are covered with a scenario of frozen ground with lots of single layer of plastic and therefore do Air Movement and rain. not need an inflation fan to create the Orientation airspace between double layers of An ideal high tunnel site allows the In addition to surface water, film. Similarly, passive ventilation is free flow of air in summer and subterranean water and seasonal generally adequate. If you decide that provides protection from cold wind in springs must be avoided or dealt with. electricity is desirable, site the high winter. For both passive and Ground water will wreck havoc on tunnels close enough for an mechanical ventilation systems to be your crops, potentially causing economical connection with the effective, the site should be open. devastating problems such as disease, electrical grid or consider using solar Adequate ventilation will help remove secondary insect infestations, panels (see “Photovoltaic Inflation hot air from the high tunnel. It will denitrification of the soil, and heat Systems” on page 48). also remove excess moisture, reducing loss, among other problems. leaf wetness and foliar diseases. If use of a backup heating system is Creating favorable environmental anticipated, the tunnel should be conditions will result in healthier

26 – High Tunnels Level and Square makes sense to orient high tunnels little East (i.e., 10 degrees) to High tunnels need not be on a level along an East-West axis. The facilitate more solar energy earlier in site. A little slope is okay, and a very Zemelskys, who grow year round in the day and warm up the high tunnel gradual slope from one end to the five high tunnels in Connecticut, quicker. other can actually be advantageous. found that their newest structure—the This allows better flow when using only one oriented East-West— Capacity of Soil to Support low-pressure drip tape (with the outperformed their four others which the Structure headers and manifolds at the top), and are on a North-South axis. Most greenhouses and high tunnels offers the ability (if needed) to blend use ground posts that are installed into the high tunnel into the existing When the sun arcs low across the the ground two to four feet deep. terrain without as much excavation. southern sky during the winter Ledge, boulders, coarse stone, or This slope also facilitates the addition months, solar radiation strikes the other obstructions can hamper of gutters if you want to collect or plastic of a North-South house at an installation. If rock cannot be facilitate the removal of rainwater. oblique angle. When sunlight strikes removed, holes must be bored with a at an oblique angle, some of the rock drill as Ed Weaver did in Too great a slope, however, can radiation is reflected outward and is constructing his multi-bay high compromise the structural integrity of lost. Solar gains in a high tunnel are tunnels. the high tunnel. Heavy snow loads greatest when solar radiation strikes that bear asymmetrically on a the cover at a 90 degree angle. A firm base is needed, especially at structure may cause its collapse. And the bottom of the ground pins and your structure should be square. Kit During the winter and early spring, an concrete. Extensive excavating and/or greenhouses with pre-drilled holes for East-West orientation improves this previous fill must be completely purlins, for example, will not align angle of incidence, more effectively settled or the ground pins will need to properly if the structure is out of capturing solar radiation. And a be placed to an undisturbed depth to square. gothic-shaped structure captures this avoid settling of the high tunnels. incoming radiation better than a Exposure and Orientation Quonset structure except when the sun Agricultural Capacity of the The site should be free from shade, as is high overhead, as it is during Soil the first principle of high tunnel summer. As a base, any coarsely textured, well- growing is ensuring full sun. Unless drained soil should be appropriate for you are already attuned to the sun’s high tunnel production. Clay soils are movements, you’ll be surprised to the least desirable base for high learn of the changes in its path across tunnels because they don’t drain well, the sky over the course of a year. thus remaining colder, and because Hills, trees (even deciduous trees), they are more prone to the build-up of and buildings can greatly restrict salts (see salinity discussion on page sunlight in the winter when sun is low 56). However, growers have been able on the horizon. Use a good sun chart to make do with a wide variety of such as the one in “The Passive Solar soils, amending and improving them Energy Book” by Edward Mazria or at as they are able, in order to www.mysundial.ca/tsp/sun_charts.html. successfully grow in these special environments (See “Soil Traditionally, greenhouses are Management” on page 54). It is more oriented along a North-South axis to economical to enrich soil in existing avoid shading. If you are certain that high tunnels to boost yields and you will only be growing during the enhance plant resilience than to add warmer months, this orientation will True South is different from magnetic more high tunnels. be acceptable. However, if you wish South. In southeast Pennsylvania, for to maximize sunlight energy during instance, it is 7 degrees West of the low light period of winter, it magnetic South. It is better to orient a

27 – High Tunnels Selecting Your Structure

etting out to build a high tunnel Single-bay high tunnels come in two tunnel owners are wise to remove is no different from any other primary shapes: Quonset and Gothic their plastic for the duration of the S capital project. The steps prior arch (see diagram below). The snowy season. to construction—planning, financing Quonset shape is relatively short and and funding, and ordering—are often squat with a rounded roof and sloped Match your structure’s design load to the most difficult. The actual building sides, while the Gothic, like a local conditions of snow and wind. project is relatively simple and can be cathedral, has a high pointed peak and Some greenhouse suppliers can select exciting. The completion of any straight sidewalls. Unheated Quonset design specifications appropriate to project has rewards of satisfaction and structures can also serve as cold your county. In the first winter, one future profit. frames for overwintering nursery northern farmer’s high tunnel— stock. Multi-bay high tunnels, purchased from a southern supplier— In shopping for a high tunnel, and including the Haygrove structure was destroyed in a snowstorm, along here we focus on single-bay described in this manual, are usually a with the perennial plant material structures, a grower will need to select series of interconnected Quonset- inside. from an array of designs, sizes, and shaped tunnels. Gothic type tunnels special features. Different materials have several advantages compared to The taller sidewalls of Gothic tunnels and construction methods can also be Quonset models. In many offer more usable space along the used. Experienced farmers have circumstances, these advantages sides for crop production and growth weighed the advantages and easily offset their greater cost. and for working comfort. For trellised disadvantages of these options for crops like tomatoes, Gothic-style their climate, markets, production A Gothic-shaped structure readily tunnels provide adequate height both aims, and bottom line. sheds snow because of the steep pitch for the interior and perimeter rows. of its roof. Quonsets, especially those The headroom over the edge beds in a Quonset or Gothic-shaped with PVC bows, need to be swept free Quonset tunnel may be so low that Structures? of snow to prevent collapse. When even a short person is uncomfortable The shape of a tunnel affects its snow threatens, some growers set up when using a walk-behind seeder, for performance. It will have an effect on 2" x 4"s as temporary props under the instance. lighting (and shading), energy gain, ridge pole, purlins, or bows of their growing space, and ventilation. Quonset-shaped high tunnels. PVC The Gothic shape also contributes to better air exchange and moisture control, and thus a superior growing environment. The greater height of Gothic tunnels allows for better ventilation through higher gable-end vents. Gothic arch roofs tend to have enough of an angle to help shed water that condenses on the interior, instead of dripping on the plants below.

In Quonset tunnels, since the whole structure is curved, opened roll-up sides expose some of the crops growing along the side to precipitation and other adverse weather conditions. This defect can be partially alleviated by purchasing extended ground posts.

Footprint High tunnels come in many sizes, in widths from 14' to over 40' and in incremental lengths. A width to length ratio of 1:2 is ideal for passive solar

28 – High Tunnels gain (See Mazria’s “The Passive To get the most from your investment, caterpillar tunnels can be constructed Solar Energy Book”). However, you it might make more sense to start with of this weaker material. It should be get more for your money with a 30' x a short, wide house (i.e., 30' x 48') and noted that PVC is a persistent poison 96' high tunnel than a 30' x 60' add on later than to buy a 16' x 96' that harms human and animal health structure. high tunnel that may quickly outgrow and pollutes the environment during its usefulness. manufacture and disposal (See “The Narrower tunnels will experience Trouble with PVC” on page 31). more heat loss than wider tunnels Also when determining the size of because of their perimeter to growing tunnel to build, take into account how Bow spacing will depend upon the area ratio. A 10' x 90' tunnel has a the structure will fit on your property. overall design of the tunnel, the 200' lineal perimeter and a 900 square What are the site possibilities? How anticipated snow load, and the foot growing area, whereas a 30' x 70' much land is available and what is its strength and capacity of its component tunnel also has a 200' lineal perimeter topography? It is critical to have steel. Although a 4' bow spacing is and 2,100 square foot growing area. enough room around the tunnel for used fairly commonly, with trusses The second structure has 133% more easy access with vehicles and placed on every other bow, growers growing area, and less than half the equipment, snow removal, water are increasingly turning to 5' bows ratio of perimeter (or heat loss drainage, and ventilation; to avoid that utilize trusses on every bow. potential) to growing area. Wider shading; and to allow for future tunnels also tend to be taller and expansion (See “Site Considerations” (See “Bending your Own Frames” on provide improved ventilation and on page 26). page 43.) interior air circulation. Baseboards and Gable- Under northern growing conditions, ends even 30' wide high tunnels can be Most high tunnels use wood for sufficiently ventilated with roll-up Selecting Materials baseboards, hip boards and gable-end sides and large gable-end vents and framing. For the gable-end, another doors. In warmer climates, in tunnels The Frame option is steel. While more costly, it with tall, dense crops like tomatoes, Historically, wood was commonly will not need to be replaced and is narrower tunnels (20' to 26') may used to frame greenhouses, but it is easy to work with. For the baseboard, more effectively reduce stale air in the has gone out of fashion because of its recycled plastic lumber, that is rot and middle of the structure without relatively high maintenance cost and insect resistant, is another mechanical ventilation. the availability of steel greenhouses. comparatively expensive alternative. Pete Johnson, a year round grower in Size North-central Vermont, is an In selecting the type of lumber to be How big should your high tunnel be? exception. He is currently growing used for the baseboard and hip board, Consider not just how much growing tomatoes and salad crops in a very consider their rates of decay. Finding space you expect to use now, but also large high tunnel which he framed lumber that is affordable, durable, and what you’ll want a few years into the with Eastern white cedar and other sustainably harvested is a challenge future. A well-built tunnel will last at local trees. For most growers, steel is and trade-offs are inevitable. For least 20 years. the best material for a high tunnel example, redwood is very expensive frame. The best greenhouse structures and unsustainable. Another important factor in are made of high tensile strength steel determining the size of high tunnel to covered with a very good galvanized Other more accessible choices, purchase is the amount of additional coating to prevent rust. (depending on location) include rot- workload you are prepared to take on. resistant wood species such as the Steve Moore estimates that a 30' x 96' An alternative to steel for the cedars, cypress, black locust, and high tunnel that is intensively planted structural members of a high tunnel is Osage Orange. White oak can also be with multiple crops can take 10 hours polyvinyl chloride (PVC) pipe. Price used, though it will need to be or more of labor each week after is PVC’s only real advantage replaced after about eight years, the initial set up and skill development. compared to steel. Mainly it is used in second time you replace the tunnel’s Marketing time is additional. When a farmer-built tunnels. Tunnels whose polyethylene film. Cheaper but less farm uses a simple cropping pattern, bows are made of PVC pipe are more attractive options are hemlock, pine, like Slack Hollow Farm’s winter prone to collapse under snow load and and spruce, listed from most to least spinach system, regular management wind. Only narrow high tunnels with a rot-resistant. time can be greatly reduced. Quonset-shape and smaller walk-in or

29 – High Tunnels The Trouble with PVC: A Cheap but Unsustainable Material Due of the dangers of exposure to human and animal health, CCA Polyvinyl chloride (a.k.a. vinyl or PVC) is a chlorinated hydrocarbon, like (chromated copper arsenate) pressure- DDT and dioxin. During PVC production and disposal, very large quantities treated wood has not been produced of hazardous organochlorine chemicals are produced unintentionally and for most residential and general released into the environment. As a result of its intrinsic hazards, PVC is consumer uses since 2004. Two under intense scrutiny in many countries, by governments as well as Canadian government agencies, environmental and health advocates. Environment Canada and Health and PVC is virtually impossible to recycle because each PVC product contains a Welfare Canada, consider arsenic to unique mix of additives. Even in Europe, where PVC recycling is more be a “non-threshold toxicant” (i.e., a advanced than in the U.S., less than 3% of post-consumer PVC is recycled. substance for which there is believed And even most of this tiny fraction of PVC is merely “down-cycled” into to be some chance of adverse health other products, so the amount of virgin PVC produced is not reduced. effects at any level of exposure). Arsenic leaches out into soil and is The production of chlorine for PVC uses as much energy as 80 medium- taken up by plants. Organic farmers sized nuclear power plants would generate. Chlorine production is an are prohibited from using arsenic- extremely energy-intensive process that consumes about 1% of the world’s containing pressure-treated lumber. total electrical output. Among the toxic chemicals produced during the PVC lifecycle are Borates are one of the arsenic-free chlorinated dioxins, chlorinated furans, PCBs, hexachlorobenzene, and wood treatment alternatives already octachlorostyrene. Workers and communities are exposed to high levels of on the market. Treating oak with the toxic substances released into water, air, and soil due to PVC production. approved borate products may These toxic substances are also released when PVC is incinerated. lengthen its lifespan to 12 years. Steve Moore has treated oak with sodium As a group, toxic by-products of PVC production are highly persistent. These tetraborate and sodium octaborate, chemicals do not degrade in nature, so they build up in the environment. both of which may meet organic Transported by wind currents and water, their presence has been documented standards if from mined sources. He even in the most remote regions of the globe. uses these food grade borate products Since these chemicals are fat-soluble, they build up in the tissues of living as they can be readily and organisms. In species high on the food chain (like humans), the levels of these inexpensively obtained from local chemicals can be millions of times greater than in the environment. In mammals, chemical suppliers. Borate wood these chemicals easily cross the placenta and concentrate in breast milk. preservatives such as Boracare can be purchased from pesticide distributors. Some of the toxic chemicals produced when PVC is made are dangerous They penetrate into the wood much even at extremely low doses. For instance, at doses in the low parts per more effectively than the food grade trillion, dioxin causes damage to fetal development, and the immune and materials dissolved in water. endocrine systems, and impairs reproduction. Cancer and brain and nervous system damage are also associated with exposure to these organochlorines. End walls can be made of plywood In its pure form, PVC is rigid and brittle. To make flexible vinyl products, (painted is best), twin wall large quantities of plasticizers called “phthalates” are added. Phthalates cause polycarbonate sheets ($1.50/ft2), other cancer, infertility, testicular damage, reduced sperm count, suppressed structured sheets, or just polyethylene ovulation, and abnormal development of male reproductive tract in lab film ($0.10/ft2). Of course, opaque animals. Like the organochlorine byproducts of PVC production, phthalates materials like plywood prevent light are pollutants that bioaccumulate (i.e., persist in the environment) and are transmission. found in the tissues and fluids of the human population. As they are not chemically bonded to PVC, but merely mixed in when the vinyl is Twinwall polycarbonate is an formulated, they eventually leach out into air, water, and other substances extruded ribbed high-tech plastic with with which the vinyl comes in contact. double walls for added insulation. It is sold as structural sheeting. For high Pure PVC is not stable, so lead, cadmium, and organotins are added to tunnels, it has an application for the stabilize vinyl used in construction and for other extended-life applications. gable-end walls. As a hoop house These stabilizers, which are toxic and persistent in the environment, are covering, it compares favorably with released when vinyl is formulated, used, and disposed. both polyethylene and glass. It (Source: Thorton, PhD, Joe. Environmental Impacts of Polyvinyl Chloride transmits up to 83% of light (more Building Materials. A Healthy Building Network Report.) than two layers of polyethylene film),

30 – High Tunnels and insulates 40% better than glass, unheated structures. In heated cover inside the structure. He also but weighs one-sixteenth as much and structures (where the interior frost is hoped to gain the benefit of enhanced won’t shatter. It is very durable and not present), infrared AC plastics light transmission and save money by cuts easily with a saw. It is far more undoubtedly retain heat better. not using another layer of high tunnel expensive than poly but costs less covering. But neither of these theories than glass. New designer greenhouse films are proved correct. In the dead of winter, now entering the market. When the the double walled tunnel stayed Plastic Film Cramers replaced the film on their warmer and outperformed the single By far the most common covers for Haygrove multi-bay tunnel, they layered tunnel. high tunnels of all types are made of chose Luminance THB (thermal heat polyethylene. UV resistant barrier) poly which costs 10% more Double Versus Single greenhouse-quality polyethylene is far than ordinary greenhouse film (See Layers superior to common construction- www.bpiagri.com/hort-luminance.htm). A double layer of poly film with grade polyethylene. It transmits light Using infrared blockers, this enhanced inflation between the layers provides better; is more resistant to wind, heat, poly reduces excess daytime heat and insulation and reduces heat loss by and yellowing; and has a longer life. scorching while also helping to 40% according to Aldrich and Bartok minimize heat loss at night. It also (see NRAES publication, It is important to replace poly film as increases light diffusion, making more “Greenhouse Engineering,”). Along recommended. For instance, after four light available to plants to increase with increasing heat retention, the years, standard 6-mil plastic loses photosynthesis and yields. In second poly layer reduces the light about 15% of its ability to transmit particular, it is recommended for level by about 10% so a balance must light. This is particularly significant ornamentals and nursery stock and has be reached. Low light levels cause during winter production, especially been shown to improve tomato yields. plants to become weak and leggy, and in cloudy climates. However, the manufacturer cautions slow down growth. As an alternative that it is not the best choice for early to double poly layers with an inflation Greenhouse film treated with anti- spring growth. fan, some farmers use multiple layers condensate additives prevents of floating row covers, which more condensation drips. Infrared re-radiant Steve Moore experimented with drastically decrease light (IR) materials are added to film to several types of plastic film over a transmission. Unless these covers are reduce overnight heat loss. In the multi-year period on two adjacent removed during the day, crop U.S., metal halides are typically used high tunnels. He compared double production may suffer. to treat the film, while in Europe layers (inflated) of the standard 6-mil phosphorous and boron compounds 4-year film with infrared re-reflectants Many farmers have found it sufficient fill this function. and anticondensate to single layer to use a single layer of polyethylene Coeava, a 7.8 mil film with reportedly on their high tunnels. However, in the Chris Wien, at Cornell University, an 8-year useful life. winter, these high tunnels will have points out that “films that lack an greater heat loss and will be colder additive which blocks infrared In south central Pennsylvania, a high than tunnels with a double layer of radiation can allow so much heat to tunnel with two layers of 6-mil, 4-year poly. And where a heating system is escape on cold clear nights that standard poly was warmer by an used, significantly more fuel will be temperatures in high tunnels are lower average of over 6°F during the winter, needed if just a single layer of poly than they are outside the tunnel. You and had superior plant growth film is employed. Using a double can have instances in which the plants compared to high tunnels with a layer requires electricity to run a small inside freeze before plants just outside single layer of 7.8 mil high blower fan. An alternative to being the greenhouse. It is very important performance plastic. Steve suspects connected to the electrical grid is a that polyethylene films used on high that this difference in thermal modest system. (See tunnels have an infrared blocker performance between the two types of “Photovoltaic Inflation Systems” on added to prevent such a problem.” film would be less significant in a page 48 and “Getting the Right Pressure warmer climate or under late fall or on Your Inflation” on page 46.) Anecdotal evidence suggests that the early spring conditions. frost forming on the inside of the Disposal and Recycling of plastic on a high tunnel is an excellent In carrying out this experiment, Steve Agricultural Plastic Films reflector of infrared radiation. Steve had thought that the lower insulating Plastic film must be disposed of when Moore thinks that it may be equal in ability of a single layer of poly could its useful life is over, presenting the value to special infrared AC plastic in be offset by using more layers of row

31 – High Tunnels farmer with a disposal problem. at very high temperatures and are When highly contaminated plastics Polyethylene covers on high tunnels equipped with mandatory pollution are used to make the pellets, more and greenhouses make a significant control devices. An early 1990s study toxic emissions result, sometimes contribution to the growing problem for the US EPA reported that 20 times exceeding regulatory limits. One of waste plastics. Polyethylene film as much dioxin, 40 times as much hypothesis is that dirt and debris limit has rapidly replaced more durable particulate matter, and many times air movement to the combustible materials in many farm applications. more metal emissions resulted from materials—a problem that increases Plastic bags and covers are used to open burning of household waste in when plastic mulches are wet. store hay and ferment animal feeds barrels compared to municipal waste such as silage and haylage, and incinerators. Originally researchers envisioned “co- palletized goods are shrink-wrapped. firing” small burners with these waste Most of these plastic films are Since that study, the gap in emissions plastic pellets and coal for heating produced from low-density from open burning versus incineration greenhouses and for other farm polyethylene (LDPE #4) resins. has grown exponentially due to applications. But pollution concerns stricter pollution control standards for may require that the pellets be burned The most environmentally sound incinerators imposed since 1995. as a tiny portion of the total mix in a disposal option for these plastics is Between 1990 and 2000 emissions of large industry or municipal recycling, which is discussed below. toxic compounds called dioxins and incinerator. The toxicity of ash from Most agricultural plastics are not furans declined by about 99% and burning plastic fuel pellets on the recycled, however, in part because heavy metals by more than 90% in 66 farm is another area of concern. recycling opportunities are few and large municipal waste incinerators. far between. Surveys in New York Recycling is a superior way to dispose and Pennsylvania suggest that about On-farm burial removes refuse from of agricultural plastics. Recycling half of agricultural plastics are burned sight, but decomposition is extremely programs are underway in the and the remainder are buried or slow and the potential exists for Northeast US and Canada for dumped on-farm. These states, like movement of water-soluble handling most types of plastic resins many others, do not restrict the on- breakdown products into used in agriculture, though their farm disposal of plastics. Therefore, groundwater. Leaving discarded geographic coverage is spotty. In the farmers have no economic or legal plastic lying around is unsightly and absence of such a program, some incentive to transport these materials gives a negative impression about farmers are stockpiling their waste to a regional transfer station or other agriculture. Pools of water that form plastic film until they have access to a central collection facility for recycling in the plastic film serve as mosquito recycling program. A trip to purchase or controlled disposal (at a landfill or breeding grounds. equipment or supplies may serve as an incinerator). occasion to bring waste plastic to a Municipal disposal in landfills or distant recycling program. Burning agricultural plastics in open incineration is a better alternative for fires or burn barrels is a burdensome disposing of waste plastics than on- In the Northeast, two successful and unpleasant job. It is also highly farm burning, burial, or non-disposal. agricultural plastic recycling programs polluting and carries short- and long- Farmers often reject this option stand out as models for government term health risks. A chemical fact because of the expense, time, and initiatives and individual sheet cautions firefighters to wear a logistics involved. entrepreneurs. A polyethylene nursery self-contained breathing apparatus film collection program was started in where there is a risk of exposure to Another disposal method—pelletizing New Jersey around 1997. This state- burning polyethylene and states that waste agricultural plastic into fuel run collection program collects fumes from molten or burning nuggets—has been under “clean” bundles of nursery and polyethylene can cause respiratory investigation by at Pennsylvania State greenhouse films. Its Mt. Holly site irritation, headache, and nausea. University researchers since 1995. accepts film from out-of-state The “densified” fuel pellets would growers. In its first five years, with Low temperature combustion of generate energy when burned with 100 to 125 growers participating, plastic film that occurs in on-farm coal in boilers. These pellets would almost 1.8 million pounds of nursery burning produces soot and other also eliminate the problem of densely film was recycled. The $20 to $25 per noxious emissions and also leaves compacted plastic bales causing “hot ton fee is substantially less that the toxic residues. These emissions are far spots” that damage incinerator $60 per ton landfill tipping fee. in excess of those released by equipment. municipal waste incinerators that burn

32 – High Tunnels With an initial aim of reducing company has installed a $10 million easier choice for other farmers in their farmers’ tipping fees, Lancaster wash line to clean dirty plastics and region. County farmer Daniel Zook started a also has a pick line to remove debris. viable agricultural polyethylene This section was adapted in part from collection business that is now The black and white agricultural films Levitan, Lois, and Barros, Ana. actually paying $80 to $100 a ton for used for mulch bags and wrapping are “Recycling Agricultural Plastics in waste polyethylene. In 2005 (its fifth not much in demand by plastic New York State.” March 11, 2003. year), Zook Plastic Recovery sold recyclers as the pigments must be 2nd ed. Environmental Risk Analysis 500,000 pounds of plastics. Zook set greatly diluted to manufacture Program. Cornell University. up the program with Trex, a company marketable plastic lumber. This is http://environmentalrisk.cornell.edu/C that reprocesses the material into relevant to high tunnel growers &ER/PlasticsDisposal/AgPlasticsRec plastic lumber for decking. Besides because, in many regions, the bulk of ycling/. Personal communications guaranteeing a market, this firm agricultural film is used by dairy with plastic recyclers and reports guided Zook through start-up and farms and feed producers, and from Penn State provided additional helped him purchase a cardboard greenhouse film alone might not be background. baler. Zook holds month-long waste abundant enough to support a plastic collection drives each spring collection program. and fall and for a couple weeks in the summer. He also accepts plastic at Agricultural plastics are also more other times. After he bales this plastic, costly and inefficient to collect than Multi-Bay Tunnels he has it hauled to a Trex factory in urban plastics, because they are Virginia. dispersed across the countryside and Multi-bay high tunnels are a special farmers dispose of these plastics category of tunnel. The most A 2003 Cornell report lists several sporadically and seasonally. Since prominent manufacturer of this type other agricultural plastic recycling concentrated quantities of agricultural of tunnel is the British company, efforts. A plastic lumber re-processing plastics are more attractive to Haygrove Ltd. As fruit farmers in facility based in Prince Edward recycling markets, recycling programs Herefordshire, England, Haygrove Island, Canada, is capable of handling may need to be organized into found single bay tunnels inadequate “dirty” LDPE plastics used in regional or statewide programs. for field-scale crop protection. With dairying. A nationwide, industry- multi-bay tunnels in Spain as an sponsored network collects high- Farmers are more likely to participate inspiration, it developed its own density polyethylene pesticide in recycling where there is a nearby model. containers. In the US and Canada, an collection system, where burning and industry-sponsored program based in dumping are prohibited, and where In Spain, where the climate is mild, Ontario, Canada, picks up, pays for, tipping fees for solid waste disposal multi-bay tunnel frames can be rather and re-processes polystyrene nursery are significantly higher than for weak. Haygrove tunnels improved on flats and trays. recyclables. Regional and statewide the original Spanish tunnel concept by recycling programs may be most making them appropriate for use in The recycling of agricultural plastics appropriate given the capital costs for the U.K. Since they were first lags behind other types of recycling recycling equipment, the sporadic and introduced in 1996, their use has due to several barriers. Municipal seasonal nature of plastic removal, the spread to 30 countries, from Norway waste transfer stations cannot easily dispersed feedstock for recycling, and to Australia, and by 2006, they were accommodate loose plastic film, the critical mass of materials needed protecting over 7,000 acres of crops. which is bulky and difficult to handle. to attract industry. Any collection site must be equipped Like other high tunnels, Haygroves to bale the material separately. Despite these challenges, enable the farmer to extend both ends opportunities for new private and of the growing season. They also The quality of agricultural plastic film public recycling efforts abound. While prevent rain, wind, and hail damage, is often compromised by greater farm use of polyethylene is reduce pesticide use, and avoid the contamination of dirt, moisture, or increasing the magnitude of the loss of harvest days due to debris. Contamination reduces the disposal challenge, high oil prices are precipitation. marketability and/or the price paid. also creating greater demand for waste For example, the Trex Company pays plastics. Farmers who use agricultural In terms of environmental less than one-fifth its standard rate for plastics should consider taking an management, Haygroves vent more plastics that require pre-cleaning. This active role in making recycling an fully than typical single-bay high

33 – High Tunnels tunnels. Haygrove’s lacing system Haygrove tunnels concentrate the run- farmers in the Eastern U.S. to grow holds the polyethylene cover securely off in the leg rows between the bays, crops in a multi-bay high tunnel. He in place while allowing a grower to and this water must be controlled. grows fall raspberries, everbearing vent the tunnels up to 8' or 10' high. Prior to construction, most growers strawberries, and cut flowers (for This design feature virtually form shallow swales that are covered October weddings) in the structure eliminates the problem of excess with weed barrier cloth. The legs are and also has five heated and unheated tunnel heat and humidity. then drilled into the soil through small single bay high tunnels. slits in the cloth. Haygroves are three-season structures. After going on the Haygrove grower They are not designed to support a Haygroves are sold in various bay tour in England, he was sold on this heavy snow load. In temperate widths and heights to accommodate a type of high tunnel. Based solely on regions, the polyethylene film should range of needs. The structures are tall economic considerations, he opted to be removed for the period of time enough for tractor access and dwarf buy a cheaper model from another during which snowfall is possible. tree-fruit production. The Haygrove company (which we will refer to as The film is “hibernated” by pulling it design allows adjacent bays to be “Brand X”), instead of a Haygrove, off the hoops, down onto the Y of the managed for different microclimates, which it superficially resembled. He legs, and covering it with black plastic with curtains dividing bays with cool purchased a four-bay structure that that is secured with twine. This and warm crops. The configuration of covers a quarter acre for under eliminates any chance of snow these tunnels provides for easy $7,000; each bay measured 26' x 100'. damage to the tunnel and protects the expansion of growing area to the sides A Haygrove covering a third acre film from UV exposure when not in or ends. would cost $12,000, in part because use. At the beginning of the next the shipping is the same whether one growing season, the film is remounted These tunnels retail for about half the buys an acre or a fraction of an acre. on the hoops and secured with the cost of traditional, single-bay high rope lacing. tunnels. The minimum Haygrove “There are many subtle differences purchase is a half-acre; however, a that you can’t see in the catalogue,” Haygroves can withstand relatively full trailer load contains two acres and says Rob, explaining his high winds. Each Haygrove leg and the delivery cost is the same whether disappointment at the weaknesses of anchor has an auger welded to it, and the trailer is full or not. the structure he selected. He has had these are drilled 30" into the soil; to modify and reinforce the high cement is not used. This keeps Construction time is faster for these tunnel in order for it to function. Haygrove tunnels from lifting out of multi-bay structures than for Contrasting the two companies, he the soil, something that can happen traditional high tunnels. Typically, characterizes Haygrove as “farmers with single bay tunnels that are not growers report 250 to 300 man-hours turned metal benders” and Brand X as cemented into the ground. During to construct an acre-sized Haygrove “metal benders who happen to make high winds, Haygroves should be left compared to 75 or 100 hours for a 30' products for farmers.” fully vented. This decreases pressure x 96' tunnel (1/12th acre). on the tunnel by allowing some of the Construction involves relatively few While on the tour in England, he wind to move through the tunnel tools and no lumber. Along with watched how quickly the Haygrove while still shielding the crops from its delivery, Haygrove provides on site went up. The Brand X structure took full force. hoop bending and construction much longer to assemble and training for customers. Since these construction was far from smooth. Most growers in temperate climates tunnels follow the natural contours of “There is no comparison,” Rob vent (open) and close their tunnels the land, there is no need for heavy observes. A major difference is that every day for the first six weeks or so equipment to prepare a level site. Haygroves can be constructed out of of the season and then leave them extra-long pieces because they are completely vented for the majority of Inferior Multi-Bay High shipped from the United Kingdom in the growing season. No special Tunnels a container and then delivered as a attention to venting is required during One farmer decided to buy a less unit to the customer. Haygrove the period when severe thunderstorms expensive multi-bay structure to save personnel come and bend the hoops are most likely. Daily venting and money, and regrets his purchase. Rob on the farm. closing is again practiced during the Hastings, the owner-operator of fall. Rivermede Farm in Keene Valley, Brand X’s multi-bay high tunnel New York (in the Adirondacks), may consists of multiple pieces that need be one of the most Northern-most to be bolted or screwed together. For

34 – High Tunnels instance, there are five pieces in each poly cover is secured to the vegetables, cut flowers, greens, and Brand X hoop while a Haygrove hoop framework with the same rope lacing herbs. comes as a single piece. “I had to find system used on Haygrove’s multi-bay a flat surface on the farm to assemble tunnels and therefore provides the hoops so they would not be excellent venting. With a minimum twisted.” Each of these joints presents 10' height at the peak, it has a large air a weak spot, and Rob has experienced volume for its size. Being a single-bay a plethora of failures around these tunnel, the Solo seals well for joints. “I had to double screw every maximum season extension. Like hoop where it joins the Y post,” he other Haygroves, it is sold as a three- says. “It either tore out the tek screw season structure and is not engineered or bent them.” for snowload.

Rob has identified various annoying Solos can be erected on hills or design flaws in the Brand X. In a uneven sites and compared to other Haygrove the hoops rest on the Y post single-bay tunnels, much less The size of walk-in tunnels is and no water can get in and freeze. construction time is required. As with variable. They range from 8' to 18' in The Brand X structure allows water to Haygrove’s multi-bay high tunnels, no width and cover two to four beds. enter and freeze. Haygroves have a carpentry or extra materials are Their length may be from 24' to 300' peg at the top of each Y post for tying required. While Solos are single-bay or more, depending on the length of the rope to that keeps the plastic film tunnels, they can be built on double beds they are intended to cover and on. The Brand X lacks the peg and prong anchors (8" between bays) to limits to the sizes of available covers. there is nothing to tie to. cover large areas. The flexible tunnel length enables a grower to construct a walk-in tunnel The Haygrove has an effective way to A Solo package, including the poly virtually anywhere on the farm finish off the end walls ands film cover and 12 mil roll-up doors because it can be sized to fit into a simultaneously provide wind bracing. for both ends, costs about $1 per farm’s existing bed system. The The Brand X structure comes with a square foot, or about half the cost of a tunnels are tall enough to walk in and reinforced plastic end wall which has more conventional high tunnel. are accessed by ducking under the not been satisfactory. “The flopping sides anywhere along their length plastic acts like a gigantic sail tied (hence their name). down with an anchor,” observes Rob. He plans to do some cross bracing to Bows for walk-in tunnels may be shore up the plastic. Walk-in Tunnels made from PVC, electrical conduit, or galvanized steel hoops. To erect the The lack of technical support is (Caterpillars) tunnel, the bows are either slipped another major frustration. “Brand X over ground stakes made of rebar or barely knew I had bought one,” he Walk-in tunnels are inexpensive tubular steel, or the bows are set says. “When I called, I was talking to alternatives to the greenhouse-like directly into the ground about a foot someone who was clueless and who structures that come to mind when deep. Bows are spaced six to ten feet was not a farmer.” Rob recommends thinking about high tunnels. For an apart, depending on the site’s wind other farmers learn from his mistakes equivalent area under cover, they cost exposure. It is best not to construct the and “invest in the best.” “I’m sorry I less than a quarter of the price of a tunnel broadside to the wind, but if didn’t ask questions,” he concludes. more traditional high tunnel. With that is unavoidable, the tunnel will respect to environmental serve as an effective windbreak for Single-Bay Tunnels in the modification, they are intermediate crops planted on its lea side. between traditional high tunnels and Haygrove Style the low tunnels commonly used by Haygrove’s newest product is the A 1/4'' rope tied from hoop to hoop is vegetable growers. (See “Low “Solo” single bay tunnel. It comes in used to form a ridge purlin. The purlin Tunnels” on page 38.) sizes appropriate for the smaller is attached to heavy-duty ground grower. Typical dimensions are 24' x stakes at both gable ends. The Due to their segmented appearance, 200' and 28' x 200'', though various structure is quite “loose” when some growers call these structures widths and lengths are available. This uncovered; much of the tunnel’s “caterpillar tunnels” (see diagram). Quonset-shaped structure is built of structural integrity comes from the They have been used to grow 14 gauge galvanized steel hoops. Its

35 – High Tunnels cover and the way it is secured to the temperatures. During the coldest Farm Tek, “the only source of very ground. periods of the year, sections of the long plastic” of which they are aware. sides (the cover) are propped up with Their other walk-ins are skinned in Walk-in tunnels may be covered with short “Y” shaped props or branches Typar. greenhouse plastics, heavy spun- cut for the purpose. When bonded fabrics such as Typar, or temperatures warm, the sides may be Caterpillars have become important shade cloth. The cover should be rolled up along the entire length of the on Windflower Farm because they are matched to the intended use of the tunnel. Clamps or tall “Y” props can easy to construct and cover, and are structure. The less expensive Typar help hold the rolled up plastic in inexpensive, while providing many of might be the better choice, for place. The sides must be rolled down the benefits of a multi-bay structure example, if the goal is to give a boost when high winds threaten. like a Haygrove. Steel hoops and (or provide insect protection) to cool- plastic film for one of their 16' x 200' season crops such as spring greens. These tunnels are highly portable. tunnels cost them about $1,500, about Greenhouse plastic would be the They may be erected and dismantled one-third the cost of a Haygrove better choice for an early planting of relatively quickly. For example, two multi-bay high tunnel. In addition, air tomatoes. And shade cloth might be 200' long units built to cover three flow in caterpillars is excellent— selected for rooting strawberry tip beds of lettuces were erected by Ted better than in a more expensive, cuttings. and Jan Blomgren and a co-worker conventional high tunnel—as over the course of a morning. caterpillars open fully like a The covering is held fast by 1/4'' ropes Haygrove. (But unlike a Haygrove, that are drawn over the top of the One way to reduce the annual costs of management of high winds in a structure (Canastoga wagon-style) and construction and dismantling is to caterpillar requires closing the sides.) are secured to stakes or earth anchors leave the caterpillar tunnel in place in the ground. These ropes give the from year to year, and to develop a list To get high quality fruit early from structure its segmented, caterpillar- of tunnel crops around which a crop their first planting, Ted and Jan like appearance. The edges of the rotation plan might be developed. transplant zucchinis and cucumbers plastic are left loose, but the covering into walk-in tunnels on May 1. These should be sized so that there are at Walk-ins are highly adaptable tunnels span three beds that are six least two feet of extra material on structures. They may be built over feet on center. Early harvests of both each side. In particularly windy existing crops, or over bare ground for of these vegetables are important in locations, the covering may be a later planting. They may be built in meeting their goal of delivering a secured by placing rocks or small the fall, left uncovered during the diversity of “real vegetables” (as sand bags on the edges of the plastic. winter, and then covered in the spring opposed to salad greens) to their New At the gables ends, the plastic is for an early planting. Or they may be York City-based CSA membership. bunched together using rope, and the used to cover tomatoes during the rope is tied to a secure stake. The spring and summer, and then taken Cucumbers, planted two rows per bed tunnel’s dimensions should be down and reconstructed over an into black plastic (or six rows across a configured to fit commonly available existing fall spinach crop. tunnel), start yielding a substantial greenhouse films or floating row harvest by the end of June. The covers. Caterpillar Tunnels at zucchinis go into bare ground, with Windflower Farm one row running in the middle of each While they have many advantages, Ted and Jan Blomgren have found of the three raised beds. Each row of starting with their cost, walk-in many uses for walk-in tunnels to zucchini is sandwiched between rows tunnels are really three-season produce vegetables and cut flowers. of quick Asian greens. These greens structures. The wide bow spacing that On Windflower Farm in Easton, New will be harvested by the middle of keeps them cost-effective greatly York, they construct some of their June just as the zucchinis are filling reduces their snow load capacity, so caterpillars with metal bows spaced out the space. By the end of the first the covering should be removed 10' apart, and others using PVC bows week of July, the zucchini harvest is before winter. However, walk-in spaced 6' to 8' apart. At any given going strong. tunnels with a bow-to-bow spacing of time in the growing season, the 4' and a width of 10' have reliably Blomgrens may have as many as On May 1, tomato transplants are withstood snow. 9,000 to 12,000 ft2 of walk-in tunnels planted into three beds in walk-in on their farm, with the typical tunnel tunnels for first harvest in July. Using Walk-in tunnels must be ventilated 200' long. Most are covered in 6 mil the hybrid variety ‘Mountain Spring’ manually to avoid excessive greenhouse plastic obtained from as their mainstay, Windflower Farm

36 – High Tunnels gets a high quality fruit that bears well minimum of two people to install a pounds per plant on their 500 plants. over a long period of time. In 2005, plastic cover. (Production varies considerably they harvested from their May 1 among the diverse heirloom varieties planting until late October. They have On walk-in tunnels built for fall grown at this farm.) At $3/lb. for #1 also produced eggplants and bell lettuce and salad mix, they may still fruit, and $2/lb. for seconds, Chris and peppers in walk-in tunnels. use Typar as the cover. Ted and Jan his wife, Tammara Van Ryn, grossed sometimes build tunnels over beds almost $16,000 on this crop, produced The Blomgrens initially experimented where they have already set in one-eighth of an acre of caterpillar with walk-in tunnels to protect China transplants. Using a marking rod, they tunnels. asters from aster yellows, a disease pound in stakes at 10' intervals and transmitted by leafhoppers. The then lower hoops over the stakes. For Chris used 1-1/2" diameter Schedule alfalfa fields that surround an inside cover, they use a midweight 40 PVC pipe, rather than steel, for Windflower Farm are leafhopper fabric, such as 0.9 ounce Covertan, bows. The bows are spaced every 6' habitat. Ted says they skinned these suspended over low wire hoops. They and placed on rebar stakes, with a tunnels with Typar because “We harvest mature lettuce from these rope and another pair of stakes in thought we could get away without unheated tunnels as late as between. His tunnels are 10' wide, rolling up the sides,” something that Thanksgiving. Ted cautions that this which allows just two rows of wouldn’t be possible for plastic- design has no capacity to bear snow. tomatoes per tunnel. covered tunnels which trap heat more effectively. “Now, tarnished plant bug Caterpillar Tunnels at New Ideally, he said, the tunnel would be 2' is our only insect problem,” says Ted. Minglewood Farm wider, with a corresponding increase In 2004, Chris Lincoln grew half his in height to accommodate the Besides preventing aster yellows, the tomato crop at New Minglewood indeterminate varieties that he grows. tunnel environment produced China Farm in walk-in tunnels. Better yields As it is, when the plants fill out, they asters with stems three feet long. and a higher percentage of #1s have are a bit crowded and grow into the Short-stemmed cut flowers are not convinced him to raise his entire sides and roof of the tunnel. The desirable and Ted and Jan realized tomato crop in these tunnels. This actual size is perfect for determinate that the extended stem length was a year, he used four 100' long tunnels to tomatoes, which he does not grow. benefit that tunnels could provide grow 800 row feet of heirloom other cut flowers. The absence of tomatoes for retail sale at a farmers’ Wind is the biggest threat to the walk- wind and reduction of light in the market and to restaurants. in tunnel design, but built properly, walk-in tunnels are two factors they seem to hold up adequately. associated with longer stems. Chris notes higher yields, higher Unlike a more conventional high quality, a longer harvest season, and tunnel, where the plastic is attached Windflower Farm currently grows cleaner fruit as benefits of growing directly to a steel frame, walk-in stock, snapdragons, godetia, larkspur, fresh market tomatoes in these tunnel plastic is held down by ropes Bells of Ireland, and lisianthus in tunnels. He also counts the low cost of secured to the earth by means of rebar walk-in tunnels to achieve much the tunnels and the ease of moving stakes or earth screws. Like the earlier blooms and longer stems. They them to different sites on the farm as Blomgren’s structures, Chris uses have come to prefer walk-in tunnels to advantages to walk-in tunnels when ropes over top of the plastic and regular high tunnels. They are also compared to more permanent, secured to long rebar stakes driven convinced that plastic film is superior stationary high tunnels. deep into the ground. If these ropes as a tunnel cover to Typar except for are not secure, wind can cause mid-summer production. In the Getting earlier tomatoes was not the damage. To prevent wind damage, it summer, they use Typar to protect overriding factor in adopting this is critical that these anchors are long against insects, diffuse the brightness growing environment. New and stout enough to hold the ropes. of the sun, and shelter the flowers Minglewood’s typical tomato from wind. schedule (reported for 2005) is as Chris believes that walk-in tunnels follows: Seed on March 28, transplant have been more time-consuming for Though they are moving away from on May 16, begin picking on July 23, New Minglewood Farm than regular Typar, Ted stresses that it has two last harvest on October 18, first killing hoop houses would be. This is mainly virtues. It costs about half as much as frost on October 21. due to the labor involved with setting plastic, and its light weight makes it up and covering these tunnels before easy to use. “I can cover a 200-foot In 2005, they sold 5,885 pounds of tomato planting and disassembling tunnel myself,” he said. It takes a tomatoes with an average of 11.8

37 – High Tunnels them later in the year after the plants easier field production. The O’Haras that these plants are winter annuals. have been removed. complement their low tunnels with They have no disease and insect pests two small 14' and 16' wide high when we grow them out of season.” Another regular task during the spring tunnels used for seedling production. and fall is opening and closing the The seeding dates for their winter and sides, depending on sun, rain, and The couple markets their mixed spring low tunnel crops are temperature. To vent, Chris rolls up vegetables and maple syrup astonishing late. They continue the plastic and clips it to a rope. Once cooperatively with Bryan’s father. planting through the beginning of the weather warms, the sides stay up Their stand always sells out at the two December and start up again in all summer. Saturday farmers’ markets their February. All these crops—which family attends from early May include lettuces, Asian greens, In 2006, Chris mulched with black through Thanksgiving. The nearby spinach, kales, Claytonia, scallions, landscape fabric. He used a weed Willimantic Food Co-op, which just beets, carrots, dandelions, parsley, and barrier fabric to accelerate tomato tripled its store area, is their other arugula—are direct seeded with an development, suppress weeds, and major outlet and has a standing order Earthway seeder. Normally, harvest prevent soil splash on the plants. He with them. continues until Christmas and then chose a 6' wide fabric and covered the resumes in March. The mild winter of 2' wide space between tunnels as well Several factors, including southern 2005-06 allowed them to harvest at as all the ground inside of the tunnels, exposure and wind protection, help intervals in January and February as enabling him to locate the tomato make low tunnels feasible for well. rows at the intersection of two pieces impressive season extension at of the fabric. This arrangement Tobacco Road Farm. The low tunnels At Tobacco Road Farm, beds are eliminated the need to burn or cut at the farm are situated on a sloping, standardized at 3' wide, separated by plant holes into the fabric. southwest facing field. Conifer 8" wheel tracks. For this bed width, windbreaks mitigate the prevailing the wire hoops must be at least 80" west wind. A third environmental long. The hoops are about 24'' high at advantage to this site is a large center. The minimum hoop size is damned river the size of a small lake 3/16" round stock. Either steel or Low Tunnels: An located beyond a grove of trees next galvanized will do. Wire hoops are to the field. spaced 2' to 2.5' apart. The tunnels are Alternative to High covered with two layers of plastic at Tunnels But this is not a snow-free frost, usually in early October. In environment. While most snowfall is March, the warming sun prompts the In some climates, low tunnels can be light, the O’Haras may receive as removal of the plastic film and its an inexpensive alternative to high much as 8" or 10" of snow at a time. replacement with Agribon. This spun tunnels for cold weather season And though snow usually melts in a polyester row cover breathes and lets extension. Low tunnels are simple, few days, their low tunnels have been water pass through. Both the plastic protective structures consisting of covered by snow for a month, without and the fabric row cover are held wire hoops covered with polyethylene harmful effects on the plants inside. down with up to a dozen 6 ml black or fabric row covers. Though more However, when the tunnels are plastic sand bags. labor intensive, with well-planned covered in snow, harvest is beds, they can be assembled with just impossible. Bryan buys 20' lengths of steel wire at a small investment. a local metal shop and has them chop The O’Haras have been using these it in thirds, precisely the length he On Tobacco Road Farm in Lebanon, inexpensive tunnels for about 10 years needs. Bryan has used the same steel Connecticut (about an hour east of at an annual cost of about 7.5 cents wire for over 10 years. Chafing from Hartford), organic market growers per square foot ($3,000/acre) to surface rust only occasionally causes Bryan and Anita O’Hara have over an extend their growing and harvest rips in the Agribon row cover, while acre of low tunnels for extending fall season. At first, their goal was to push also helping to stick the cover onto the vegetable production and growing a fall production later. Driven by strong hoops. Galvanized steel is much more variety of baby and braising greens customer demand for the good-tasting, expensive. and other vegetables throughout the cold weather-grown greens and their colder months. The low tunnels are need for farm income, they just kept For ease of operation, the beds are removed in late spring to allow for on expanding their off season covered in 40' sections. Wind build up production. Bryan said, “We realized makes longer sections unmanageable,

38 – High Tunnels and with the length of this low tunnel, For several years, Bryan has been • Low tunnels allow farmers to grow two people working together can selecting Asian greens and arugula for without insect and disease uncover a whole field in little time. cold hardiness. This breeding has pressure. Bryan uses two layers of cheap 1.5 yielded quick results, boosting winter • Since low tunnels are closer to the mil construction grade plastic. A 200' survival from 10% to 100% in arugula earth, they provide more heat to the length of this film will suffice for two just by collecting seed from planted plants in the day. Bryan said they 40' sections. To close the ends, 50' of that made it through the winter. For are 3° to 5°F warmer than ambient plastic is needed to skin 40' long low his first breeding experiments, Bryan temperature on cold nights, similar tunnels. The ends are bunched up and seeded three adjacent beds of Mizuna, to their high tunnels. pulled tight to create tension over the Tatsoi, and Miruba. He replanted the • Cold growing conditions enhance top of the hoops. next year from the seed he harvested the taste of the crops. from the Mizuna mother plants which • Low tunnels convert readily for Bryan is an enthusiastic missionary successfully over-wintered. Each year regular summer production, for the environmental control he collects seed from subsequent allowing triple cropping. provided by low tunnels. They generations of plants interbred from • Soil preparation and other tractor prevent excess precipitation from the three cultivars that survive the operations can be carried out in the damaging germination and ruining winter. The hybrid seed selected from field prior to quick installation of crops, and protect crops from wind a large gene pool produces very the low tunnels. and cold. Bryan has measured a 35°F vigorous plants with much greater • As they are easily removable, low gain on sunny days. The low tunnels cold tolerance. He can stagger seed tunnels reduce soil salt build up. should be vented if the outside production by altering when he temperature reaches about 70°F and harvests for salad mix. The O’Haras also recognize that low opened to catch precipitation if tunnels have the following excessively dry. In 2005, Bryan kept Chickweed is the biggest weed disadvantages, some of which are the beds uncovered until the problem in winter low tunnel common to high tunnels as well: extremely late first frost on October production. Before they grew year • The biggest issue is that low 21, a lapse he came to regret since 20" round, the O’Haras used to tolerate tunnels are more labor intensive. of rain that month broke all records. If chickweed in their fields over the To hoe, harvest, or irrigate, the the beds had been covered, the crops winter so now they are grappling with coverings must be removed. would not have been devastated and it a huge seed bank. Seeding crops very • Low tunnels cannot be automated would have been more possible to late in the fall allows late tillage, and require a lot of bending to control chickweed with cultivation. reducing chickweed germination, and manage the cover, causing worker the Asian greens sown on December 2 discomfort. Irrigation is rarely required until later were their cleanest over-wintered • Low tunnels restrict access in winter. The plants seem to like it crop. compared to high tunnels. One drier in winter, Bryan explained, can’t harvest on a cold, windy day. noting two mechanisms that plants use At Tobacco Road Farm low tunnels to withstand cold temperatures: have a variety of advantages: • Cut lettuce grown under plastic film-covered low tunnels (or high desiccation and mineralization of their • Low tunnels are very inexpensive tunnels) is very delicate and wilts sap to reduce their freezing point. and quick to install. Bryan quickly. This is one reason to These mechanisms make these crops estimated that two people could convert to a fabric covering like extremely sweet-tasting in the winter. cover over an acre in two days. Agribon. • In the spring, low tunnels are more Low tunnels provide a perfect In the central Connecticut climate, easily cooled than high tunnels to • environment for chickweed, the snow build up has not been a problem prevent bolting. ultimate winter weed. for the low tunnels. The hoops are • Low tunnels are easily converted • The plastic cover on low tunnels pushed down by snow load, but pop from plastic to cloth covers. must be vented during warm sunny up, pushing off the snow, as soon as • Low tunnels allow farmers to late fall and winter days. the sun begins melting it. Snow manage water, protecting crops and accumulation on the wheel tracks soil from excess rain and wind. A (An earlier version of this profile insulates the low tunnels, provides a slight slope allows water to run off appeared in “Growing for Market.”) windbreak, and also holds down the the tunnels. row cover.

39 – High Tunnels

Construction Tips

oop house construction can be • cordless drill and drill bits (plus confidence whenever you are ready. as exacting or casual as you spares) for the various size There is nothing worse than grabbing H like. However, not paying fasteners you plan to use; an hour here or there to work on a attention to initial details can cost • good step ladder; high tunnel only to find that someone extra time in the long run, and the • socket set; bumped the stake and all your work is resulting structure may not look as • drift punch or pipe wrench; now out of line. nice or stand as long. • miter saw or circular saw; • speed square; Ground Posts Two people with good construction • hacksaw or saws-all; As farmers, we are striving for a skills can erect a 30' x 96' high tunnel • power cord; and loose, well-structured soil in which to in about a week. The 75 to 100 hour grow our plants. But we need a • tape measures (12', 25', and 100'). estimated completion time assumes medium with the opposite that all materials are on site. Setting characteristics to support a building. An experienced high tunnel builder up the metal frame, installing (If you have concerns about your site advises: “a cordless drill (preferably baseboards and hipboards, roll-up and its ability to support a high tunnel, one with ample batteries) will be your sides, and building endwalls are check with a qualified professional.) best friend for fastening those millions included. Additional time will be of quarter inch bolts and nuts.” required for site preparation, utility A high tunnel’s foundation is installation and covering the tunnel provided by ground posts, which are with polyethylene film. Batter Boards steel pipes partially buried in the It is important to set up batter boards ground. On rocky ground, in high at the start of high tunnel construction Most manufacturers provide wind areas, or where significant (see Diagram 4 below). The small instruction manuals with the frame ground disturbance occurred during amount of extra time involved will be and technical support if needed. site preparation, a little additional well-rewarded by the increased ease Some, however, are less helpful than support may be warranted. In these of construction. The use of these others in their support so inquire specific situations or for extra semi-permanent building markers is before selecting a company. The most stability, a couple shovels of cement described at important step is to make certain that will effectively keep ground pins in www.dulley.com/deck/deck01.shtml. the site is square and uniformly place. pitched or level. If this is done Batter boards define the corners and carefully, the frame should install A sledgehammer is commonly used to heights of the high tunnel. They allow easily. drive in short ground posts. Most you to erect the structure with companies provide a protective piece Instead of step-by-step instructions for constructing a high tunnel, here we offer tips to save you time and money. We hope these recommendations enable you to complete your project with less stress and more confidence.

Start with an adequate selection of tools to make the construction process a pleasant one. Tools to assemble include the following: • level, level string, chalk line, and transit; • long-handled mallet or sledge hammer for driving ground stakes; • post-hole digger for endwall posts;

40 – High Tunnels to put in the pipe to protect the end To ensure that the posts are placed at Raising a heavy bow on a wide tunnel from being damaged or the correct height, use a transit, hose (20' or wider) is best accomplished “doughnuting.” For a taller structure level, or laser level. Then take down with at least three people. One person with extended ground posts, John the batter boards and run a high- stands at each leg of the bow, and a Biernbaum (who researches and strength nylon mason cord between third pushes the bow up in the air with teaches about high tunnels at the corner ground posts. Pull the a pike pole. This is heavy work. Each Michigan State University) has found string as tightly as you can to bow will need to be picked up and that a post or fence pounder works minimize droop over the long wiggled onto the spline/ground posts. better. distance. Be careful; if a tight nylon Use one or two pike poles to keep the string breaks, it can hurt someone as bow assembly from falling while the The ground posts at the four corners the end whips past. crew wiggles it onto the ground posts. should be solidly cemented in. For tunnels over 70' long, also cement in The bows – and therefore the ground Purlins the intermediate ground posts in the posts – of most high tunnels are Purlins help stabilize the high tunnel. middle of the long sides. Cement must spaced on 4', 5', or 6' centers. A They are bolted to the bows, along the be placed below the soil freeze zone, wooden template with notches at 4' length of the structure. Typically a 30' as the freezing action can force the (or whatever the bow spacing is) tunnel will have five purlins, ground pin up out of the ground. You eliminates the need for the time- including the ridge pole. may want to use caution when consuming and awkward task of employing cement as this may move measuring from bow center to center. The purlins can be attached once the the structure into a ‘permanent’ Ledgewood and Rimol provide their bows are loosely assembled and in classification. greenhouse customers with these place. A platform is much safer than spacers. They are also easy to make. ladders and saves a tremendous Steve Moore suggests a good way to John Biernbaum regards them as amount of time and energy. Use a hay keep the ground posts in place so they essential for construction. wagon, truck bed, or scaffolding, don’t pull out of the cement or slide especially if you can pull it along as down: pre-drill the ground posts Alternatively, Steve Moore you go! within 2" or 3" of the bottom and recommends measuring from the insert a 4" to 6" piece of rebar. same side of a post every time to A drift punch or pipe wrench can be attain an accurate center used to help align bow and purlin The ground posts need to be in the measurement. Taping the end of the holes. As you attach the purlins, right location and at the right height. measuring tape to the corner ground tighten all bow bolts, except those that A jig made with two old boards and post is one simple way to do this. A connect the bow to the ground pin. some broccoli-type rubber bands or level should be used to ensure the Finally, when you are at the end bow, thin bungee cords will align the posts posts are vertical/plumb. A post level with all the purlins in place, you are with the strings between the batter that has bubbles at 90 degree angles is ready to “plumb” the gable end to boards that outline the high tunnel. useful because both directions can be straighten the entire bow/purlin (See diagram below.) It will also keep seen at once. assembly. the posts at the desired height. This simple device is removed once the Bows Attach one string with a plumb bob to cement hardens in 12 to 24 hours. Bows typically consist of two or three the top point of the outside edge of the shorter pieces of metal tubing. last bow, and a second ground string Preassemble bows loosely. Do not to the outside edge of the bottom bow. tighten the bolts. This loose bow Allow the plumb bob string to come assembly will help in purlin within 1/8" of the ground string. installation. (Purlins are horizontal pieces typically made of pipe that is a A good way to adjust and hold the smaller diameter on one end high tunnel plumb is to attach a come- (swedged) to fit inside the next pipe.) along to a large immovable object like a tree or truck and then attach a rope Historically, pike poles were used to or chain from the come-along up to push up large sections of timber the bow. A come-along’s ratcheting framing for barns. Pike poles also mechanism and its steel cable allow have a place in erecting high tunnels. for quick and precise alignment of the tunnel. Now you can tighten all

41 – High Tunnels remaining bolts and install the wind the bow. Ted Blomgren recommends If you use a rigid gable-end covering, braces. using a washer on the wood screw. such as polycarbonate, the outside of the baseboard will need to be flush Baseboards The frame will be complete after the with the outside of the bow. To make The baseboards sit on the ground hip board (2" x 6" lumber) along with it flush, attach an 8" piece of universal along the sides of a high tunnel. They “poly lock” or “wiggle wire” base is corner (a thin-walled piece of angle are bolted to the ground posts. Use attached to the bows approximately 5' iron with multiple holes for bolting) 1.5" x 8" lumber for baseboards. or 6' off the ground. (Poly lock is the with the same bolts that hold the side trade name for an extrusion for baseboard. Consider sourcing your lumber from attaching the polyethylene film to the local family-owned and operated structure. It serves the same purpose Insulation sawmills. Often boards from these as wiggle wire.) This will serve as the In cold climates, insulation can make a mills are sawn several inches longer point of attachment for the plastic significant difference in the than their designated length, rather covering. performance of high tunnels. In Zone 6, than being trimmed down to an exact, burying 1" thick by 2' wide rigid foam even foot measure. This extra length The hip board should be inspected at (i.e. polystyrene) isolates frozen ground will allow you to cut the ends at a 45 each change of polyethylene to make from growing areas. The thickness and degree angle for joining together at sure it will be sound for another four depth of insulation should be modified the bows with a 1/4" machine bolt or five years. Farmers should be according to your climatic zone. This (see diagram below). aware of rot and ready to replace the foam should be buried at an angle to baseboard as necessary; the plastic gain more benefit from the thermal need not be removed to do so. mass of the earth. The angled placement also makes installation easier and Gable Ends allows space for the cement support at Doors should be large enough for the bottom of the ground pin (see ventilation and easy access. They can diagram below). Insulation can also be span even the full width of the high used in pathways and along the lower tunnel. To maximize airflow and portion of the sidewalls. accessibility, some farmers construct removable end walls. A smaller, Use a long 1/4" bit to drill out the personal door that opens inward holes for the bolt through the wood makes a convenient winter passage. from the inside of the high tunnel. This added length is helpful when Unless the high tunnel will have very attaching framing to bows. wide doors, some tasks such as adding compost, tilling the soil, and installing Machine bolts are superior to carriage utilities are best accomplished before bolts for attaching the poly hold-down the gable ends are closed in and strips to the baseboard. Carriage bolts access is restricted. are often used for this purpose, but they rust fast. When the baseboard Gable end framing can be done with needs to be replaced, sometimes the steel or wood. If using wood, either nuts are stuck in place and won’t turn. select one of the rot-resistant species Hiring Out Construction With a wrench on either side of the recommended for the baseboards (see For some farmers, hiring an nut and bolt, the machine bolts will materials section) or be prepared to experienced crew to do the installation break off much faster and easier than replace the wood as needed. Steve may be the best option. The estimated hack sawing carriage bolts, which Moore uses rough sawn 2 x 4s to frame labor cost for basic high tunnel only turn in the wood. the gable end. When the wood rots construction used to be fifty cents to right at the soil line where moisture one dollar per square foot. However, While bolts may be better for and air meet, rather than take apart the due to inflation, the labor bill for high attaching the base boards and hip whole assembly, he just pounds in a U- tunnel construction in previous years boards to the bows, galvanized pipe shaped steel fence post and lag or may not be relevant for estimating straps can also do a good job, as long machine bolts it to the post that had costs under current conditions. Like as the pipe strap is also tek-screwed to rotted off. “This buys me a good many any construction project today, expect more years service,” he says. skilled contractors to be expensive.

42 – High Tunnels Bending Your Own Frames Rather than purchasing a hoop house kit, some farmers choose to bend their own. A good role model for this activity is Ed Person of Ledgewood Greenhouse. This New Hampshire farmer went from bending frames for his own use to developing a substantial independent business that sells and delivers high tunnel frames throughout the Northeast. For savvy shoppers, fabricating a high tunnel steel frame can save money. It also allows farmers to realize a better design idea, satisfy unique needs, or add onto an existing high tunnel. Ted and Jan Blomgren bent several Gothic arch high tunnel frames for their farm. Three people worked for about the equivalent of one week fabricating the jigs and bending and drilling the component parts for three and a half 30' x 96' high tunnels with trusses. At the time, they were able to make their own high tunnel frames for a third of the cost of a kit, thanks to a farmer friend’s tip about a supplier of economically priced steel. Ted cautions though that purchasing steel from a local chain link fence supplier might actually cost more than buying a kit with pre-bent, pre-drilled steel. The Blomgrens’ bows consisted of two long side pieces with a shorter, smaller diameter piece at the ridge. In all, they used three sizes of steel pipe—1.9", 1.6" and 1.3" diameter for bow, small ridge bow, and purlins, respectively—to fabricate all the high tunnel components including trusses. The only new tools they needed were a chop saw and drill press outfitted for cutting and drilling steel. After four years, there is no rust at the bends and the galvanized coating has not popped off. They built the two jigs needed for bending the steel for the bows by replicating a bow they had removed from their existing high tunnel. To bend the steel, they placed a jig, made of two-ply 3/4" plywood and lumber, on the level cement floor of their garage, braced against its foundation. For the easier, shallow bend, they were able to use their sedan with a steel cable attached to the trailer hitch. The more acute portion of the bow required the weight and traction of their heavy John Deere tractor. To compensate for the springback in steel, they bent it until it fit a pattern they had outlined on the floor. Bending the bows for a high tunnel can be a simpler process. For example, Thomas Christenfeld, a neighbor of the Blomgrens, bent the bows for his Quonset-style greenhouse using a silo as a jig. He stuck one end on one of the hoop bolts that holds the concrete panels of the silo together and bent the other end around the silo. Two people are needed to get a good enough bend in the pipe and that it probably only works for a single piece hoop. Thomas notes, “You cannot get any real bend in the ends of the pipe so two pieces stuck together leaves a flat part on top of the hoop house, which is far from ideal in a snowy climate.”

Another Way to Bend Your Own Kevin Loth, who is contractor as well as a farmer, has fabricated his family’s 20' x 200' Quonset-style high tunnels near Lincoln, Nebraska. The Loths have two heated greenhouses and two year round high tunnels. By bending his own bows, he was able to get twice as much ground under cover than if he purchased kits. His calculation included what he paid a helper but not his own time. He said if you don’t drill the bows, you could probably bend them in a day, though set up might take a couple of days. With a borrowed pipe bender, he made bows out of the 15 gauge metal pipe used as a chain-link fence top rail. He saved considerably on the pipe by purchasing it by the bundle of 91 pipes. Because the pipe comes in 21' lengths, he had to swedge together one and a half lengths for each bow. While a swedging tool can be expensive, often when you buy fencing steel, one end comes already swedged. His finished tunnels are Quonset-shaped, 10' high at the peak. Their bows are 4' on center, and they have two purlins but no trusses. Kevin has attached the purlins and bows in several ways. Holes should be drilled prior to bending the bows. For the less technically adept, purlin clamp connectors (available from greenhouse suppliers) or pipe clamps (from plumbing supply outfits) preclude the need to drill holes for the bolts attaching the purlins. Getting these holes to line up properly can be difficult. Moreover, the very act of drilling holes weakens the steel. While the purlin connectors are aluminum, Kevin dismisses concern about mixing metals as the tunnel’s steel is galvanized. He thinks this is less of an issue than drilling holes as that action exposes ungalvanized steel and weakens the structural pieces. Also he noted that the ends of the bows are in contact with corrosive cement and soil acids.

43 – High Tunnels Covering a High Tunnel stroke, bringing the plastic overhead plastic down to the end and finish the Farmers employ several methods for so that it clears the peak without gable end. The reason for the getting the unwieldy expanse of getting caught. staggered start and attachment is to polyethylene film over the top of large avoid see-sawing the plastic side to hoop house structures and evenly The two people walking along the side. The lead attachers must always attached. The size of your crew helps sides can have an exceedingly long keep the selvage edge the same while determine which methods are most way to pull the plastic. When they the other side pulls the plastic to feasible. The most important rule of reach the middle of a long tunnel, two match. thumb is never attempt to cover a more people standing at the original tunnel on a windy day. gable end should assist pulling the Getting all of the wrinkles out is not plastic along. These additional people important if you are going to inflate. It Covering a large (i.e., 30' x 96') high also help keep the plastic from is important not to pull the poly film tunnel with a single layer of poly becoming a sail if a sudden gust of so tight that the wiggle wire in the U should take four or five people two or wind comes along. channel perforates the new plastic. three hours. There is a learning curve so the first few times may take longer. After the whole tunnel has been A variation on the pull-over-the-end covered, it’s time to even out the method of covering a high tunnel is Method A: Pull over the end. plastic. The selvage edge must be used by the Kilpatrick family. They For this method, four or five people even for the entire length of the tunnel set up the plastic on scaffolding at one and a center-folded roll of and should be 12" or longer. You end of the tunnel as described above. polyethylene are required. (You can don’t want the edge to run out! “Make sure the scaffolding is above order your polyethylene folded in the peak of the structure. While one several ways.) If you are putting a second covering person pulls the plastic down the on, just tack it on the first layer using length of the high tunnel, the others The first step is unrolling the plastic. just a couple strategically placed poly assist from the ground.” Philip and To do this, set up a pair of fasteners (i.e., wiggle wire) and repeat Michael Kilpatrick have found that for cinderblocks a few feet further apart the process with the second covering. work on the purlins, scaffolding than the length of the roll of Otherwise, proceed to the next step. mounted on a cart is far more polyethylene. For a 12' tube, set the convenient than using a ladder. blocks about 14' apart. Then put a Once you are satisfied that the plastic pipe in the tube. Make cardboard is even on the edge, temporarily Method B: Ridge-roll. washers about 1' square to put on the secure the plastic in place at three or This is one of the two ways that the ends of the pipe. The washers serve to four points on each side. The most Blomgrens cover their tunnels. (The protect the ends of the rolled up common method for securing the other way is described in Method C.) polyethylene from abrasion against plastic is wiggle wire inserted into a U Both methods involve climbing up the the cinderblocks when you unroll it. channel. An alternative assembly is high tunnel and thus entail danger. This set up should allow the plastic to homemade—wood attached with Use these methods at your own risk. freely unroll. drywall screws every 6" to 8". Covering a high tunnel with a lean The next step, getting the plastic over Now you are ready to fully secure the crew (four people) necessitates a the tunnel, requires five people. One single or double layer of plastic. The different method. Once again, make person is stationed on a ladder at a person on the ladder inserts wiggle sure to obtain greenhouse plastic with gable end of the high tunnel. Wearing wire from the top down on one of the its fold down the center so it will a hooded sweatshirt is recommended gable ends. Next the plastic film at the unfurl properly. to avoid plastic rubbing and to other gable end should be pulled and counteract the static electric generated that plastic “tacked” down. Once one In this technique two people carry the by moving the plastic film over head. gable-end plastic is permanently entire roll of poly up to the top of the The center of the end of the poly is attached and the other gable end has high tunnel. A bucket loader is handy passed to the person on the ladder. been “tacked” in place (with a short for this purpose. Before climbing up, The film unrolls as it is pulled up the wiggle wire), one side can be attached they insert a pipe into the cardboard ladder. Two people on the ground for a distance of about three bows. tube to assist in unrolling it. With the hold the corners and walk along side Remember to keep a constant selvage roll sitting on the top purlin, they the tunnel as the plastic is unfurled. (waste) edge. Another person (or two) temporarily fasten it on the gable end Meanwhile the person on the ladder starts on the opposite side of the first of the tunnel. Then they proceed to does a sort of butterfly swimming group and both groups attach side walk it down the tunnel, making use

44 – High Tunnels of the side purlins, walking the roll For a big tunnel (30' x 96' or 150'), at If you choose to use wooden batten along as they go. By the time the pair least eight people are needed for this boards to fasten the plastic to the hip has walked halfway down the tunnel, method. Start by unrolling the plastic board, you would be wise to use a pair the plastic will have begun unfurling, (without unfolding it) along the side of batten boards one above the other with half falling down one side and of the high tunnel. If there is a risk of with the plastic outside of the top one half down the other. (This unrolling the slightest wind, it is best to be on and behind the bottom one. This more procedure will go much more quickly the windward side of the tunnel. effectively locks the poly in place. if the high tunnel is designed so that (See diagram below.) the ridge purlin is situated on top of After the plastic has been unrolled, the bow. This is an atypical purlin people station themselves at regular placement and is only advisable for intervals along the tunnel. They each tunnels that will never be covered take hold of what will become the far with a double, inflated layer of poly.) edge of the poly. Pulling this edge, they climb up and over the tunnel. Meanwhile the two other people, who With enough people, the weight of the are on the ground, are starting to poly is distributed and not tentatively connect the poly to the hip burdensome to anyone. board just above the roll up sides. Once the plastic is over the top of the After the plastic has been unrolled structure, it is squared up, and then along the entire length of the tunnel, temporarily fastened to the gable the two people who have been ends. They then proceed as in the walking the ridge with the roll of poly above description, with teams starting temporarily connect the poly with from opposite sides of one end and After you have to undo rusty screws wiggle wire at the top of the second both working toward the far end. or other failing attachments to remove gable end. They then climb down and old poly, you will probably come to join the two folks on the ground. With There is an alternative to climbing up believe that wiggle wire is a bargain at two people on each side of the tunnel, and over the greenhouse. Ropes may a $1 per foot. When attaching new they square up the plastic, and then be attached to the plastic along its poly with wiggle wire, don’t pull the begin attaching the plastic along the side. Clips available from greenhouse poly too tight (or over inflate). The top of the roll up sides. With the two suppliers can be used to secure the wiggle wire will actually cut teams working on opposite sides of rope to the plastic. Alternatively, wrap perforations (corresponding to the the tunnel, they start at one end, and tennis balls in the plastic and use them wiggle wire) in the new cover if there work toward the other end. to help fasten the rope. Toss the ropes is too much tension. This applies to over the tunnel structure and, once on double layers of poly, too. They then finish the gable ends, the other side, pull the plastic over. taking up the slack and smoothing out When attaching plastic to battens (thin wrinkles, before permanently boards less than 1/2" x 1-1/2"), use attaching it there. They trim off the Tips for Attaching the double headed nails—rather than regular nails—for easier removal. excess plastic at the gable ends so it Plastic Galvanized screws are another option. doesn’t flap in the wind. To complete Single poly can be difficult to keep on the covering, the roll up sides must be a structure because there is no tension attached. from an inflation fan to reduce flapping. Steve Moore has used wide Method C: Over the side. poly strapping placed between every Like the previous method, this other bow and attached to the covering procedure used by the baseboard to keep the cover in place. Blomgrens has safety and liability This increases the longevity of the issues. As an alternative to climbing plastic film, and also reduces a over the tunnel frame, Steve Moore farmer’s worry about losing the suggests attaching grommets to the plastic on the tunnels (and sleep) on plastic and using ropes to pull it over windy nights. the structure.

45 – High Tunnels Getting the Right Pressure on Your Inflation

Correct pressure ensures a balance between over and under inflation. By providing sufficient tightness of the plastic, flapping is minimized. If the plastic is stretched too tightly, light transmission is reduced. Simply put, correct pressure increases the life of the plastic and its ability to transmit light.

A manometer is an instrument used to measure the pressure of a gas. For high tunnels with a double poly layer, it is useful for determining the proper inflation pressure. Steve Moore makes his own homemade manometer using this simple procedure.

On the inside of the tunnel, attach a 2" x 8" (or wider) board with carriage bolts to two of the bows at a 4' to 6' height. (This board can be used to mount the inflation fan as well.) After covering the high tunnel with the first layer of poly, a 4" to 6" square piece of polycarbonate is attached with drywall screws to the wood before the tunnel is covered with a second layer of poly.

From the interior of the tunnel, drill a hole through the wood, the inside layer of plastic and the small piece of rigid material. From the inside, push a clear flexible plastic tube (available by the foot at most hardware store) into the wood, allowing the tube free access to the air between the layers. The tube's internal diameter can be from 3/4" to 1". Caulk around the tube so that it is airtight to prevent leaks.

Let the tube form a "U" with one of the top legs of the U going through the wood. Attach the other top of the U tube to the board and fill the bottom of the U with a colored liquid (blue washer fluid or colored water). Mark level horizontal lines ¼ of an inch apart on the board next to the U portion of the clear tube. If the interior air level of the U is ¼ inch higher than the inflation side of the U, then the pressure is about right. The liquid level on the side of the U that is attached to the board should be 1/4 " lower than the side of the U that is open to the inside of the tunnel.

Adjust the pressure by using a damper on the intake of the inflation fan. You can make a damper with a flat piece of metal, like an old can lid (taped to keep from cutting yourself). Insert a screw through the top edge of the metal lid. Attach it tightly enough to the intake of the inflation fan that it will stay in place at various degrees of opening.

Steve has used solar power to run the inflation fan and his monitoring equipment.

46 – High Tunnels Environmental Management

structures—allow for higher roll-up Ridge Vents Ventilation and sides than curved walls. Longer ground In ridge-vent systems, cooler air Cooling pipes or leg extensions on the bows of enters the high tunnel through roll- Quonset tunnels add height to sidewalls. up sides or gable-end openings,

Gothic tunnels also allow for bigger and hotter air rises and exits Venting to reduce humidity is more gable-end vents over the door than through the ridge vent. These important than keeping the tunnel Quonset tunnels. Caterpillar tunnels and systems work very well, but few closed to boost the temperature. The multi-bay tunnels like Haygroves high tunnel growers seem to use sacrifice of a few degrees in favor of provide superior venting, since entire them, as they are more expensive lower humidity will contribute to sidewalls can be pushed up to allow air to purchase and install. Ridge overall plant health. passage in both structures. vents can be manually or

mechanically operated. Some High tunnel ventilation is usually To prevent tender plants from being growers have even constructed accomplished by the passive blasted with cold air when roll-up sides their own ridge vents. movement of air through the structure. are vented, some growers are installing The air movement through tunnels a low protective sidewall 12 to 18" An alternative to an expensive full- occurs through roll-up sides, gable- above ground level. Poly film, clear length ridge vent is a series of end doors and vents, ridge vents, and acrylic, and polycarbonate have all been small roof vents which act as removable end walls. (See below.) used for this purpose. Roll-down side chimneys to vent out hot air. For curtains offer another solution. several years, Ken-Bar has made an inexpensive roof-installed vent Large gable-end vents and doors and for high tunnels that is available removable end doors help maximize from Farm Tek for a little over venting with no energy cost. $200. These vents have an actual Retrofitting is feasible, but planning 30" x 14" opening and should be ahead for optimal ventilation during the installed every 20' to 25'. A $50 design phase is best. solar vent opener eliminates the need for a noisy motor and an Ryan Voiland at Red Fire Farm near electrical hookup. (See “Green- Amherst, Massachusetts, purchased a house Supplies” on page xx.) 35' x 120' Harnois greenhouse kit because it seemed the best option for Although Ryan is satisfied with the ridge venting. The roof comes to a venting of his large tomato high higher peak in his model than in others. tunnel, he said he would not opt for a A 24" wide flat piece of plastic at the ridge-vented structure again due to the ridge moves to open the vent. The costs and complications of For growers who also work off the opening mechanism is powered by a construction. He believes that an farm, an automated vent is essential. small motor that is activated by a exhaust fan could adequately serve the Motorized louvers are readily available, thermostat. same function. and probably pay for themselves relatively quickly, but solar openers are The frame with the ridge vent costs Fans good alternatives to motors. considerably more than a frame Multi-bay and walk-in tunnels can be

without one. Since the frame was also vented very effectively, but the The height of roll-up sides should be more complicated, Ryan hired a narrower openings in more traditional considered when selecting or designing greenhouse builder to erect it. To high tunnels sometimes constrict a high tunnel. The higher the sidewall, access the ridge vent, his tunnel has a airflow. While passive venting is the greater the potential air movement catwalk on top of the frame. Covering usually sufficient in well-designed high through a tunnel. Sidewall height the ridge-vented tunnel with plastic is tunnels, several circumstances prompt depends in part upon the design of the challenging and follows a different some high tunnel growers to turn to tunnel. For instance, straight procedure. fans to cool their tunnels, reduce sidewalls—the norm for Gothic humidity, and improve air circulation.

47 – High Tunnels Photovoltaic Inflation Systems By Steve Moore Most traditional hoop houses or high tunnels have only one layer of poly film as a covering, so no blower fan is used. But thermal performance is far better in dual covered structures. Heated greenhouses typically use two layers of poly film and require a blower. Inflation has two functions. First, it creates a dead air space for insulation. Secondly, it provides turgor to the covering. Keeping the plastic at the right tautness prevents stretching which reduces light transmission. It also prevents tearing. There are a variety of energy sources to power an inflation fan or blower. For example, Amish farmers sometimes run inflation fans on compressed air to keep within the bounds of their faith. Otherwise, most applications require electricity. However, not infrequently, high tunnels are located at a distance from grid-connected electrical service. Hook-up can be costly. The alternative we have used is solar photovoltaics—electric power from the sun. Our independent solar power system has worked well for many years. We used a 32-watt Unisolar flat photovoltaic panel ($210), a Morningstar charge controller, two 6-volt golf cart batteries ($70 - $80 each) and a 12-volt blower fan. With , it is cheaper to reduce energy demand than to produce more energy. We were lucky in finding such a fan through a military surplus outlet. This 4-watt blower fan ($20 when available -- see resources) has a very low amperage draw. The rest of the system is built around the electric demand, in this case, the blower. The blower runs 24/7 so backup batteries are required for nighttime and long stretches of cloudy days. More northerly locations with shorter winter days may require a bigger solar panel and more battery storage capacity. The two 6-volt batteries are wired in a series resulting in a 12-volt current which is compatible with the charge controller’s needs and the solar panel output. In southeast Pennsylvania, the 32-watt solar panel was sufficient to keep the batteries charged for our long-term storage needs (times of little or no sun) and to power the blower and some monitoring equipment. We used a rather expensive charge controller so we could build on it for further expansion of the solar system. Otherwise, several small and inexpensive models ($35 to $100) would be more than adequate. It is important to protect the batteries from cold. We all have experienced how cold reduces battery efficiency, when we try to start our car on very cold days. With this concern in mind, we chose to place them in a box below grade in the ground in the high tunnel where the earth’s constant temperature moderates the cold. We also wanted to get them out from under foot and reduce the chance of spilling or puncturing the cases and releasing battery acid. You must ventilate your battery box as explosive hydrogen can be a byproduct of battery charge and discharge cycling. We do this with a few holes in the plywood lid. By sizing it big enough, we get double duty out of our battery box. It also functions as an irrigation distribution box to add or change drip tape manifolds and other needs.

The production of trellised summer high at one gable end coupled with a (HAF) fans create a gentle air current crops such as indeterminant tomatoes louvered vent at the other can help that moves and mixes air. and cucumbers with lots of foliage remove hot air and free moisture and can reduce air movement. Stagnant reduce relative humidity in the The Zemelskys had four HAF fans masses of humid air result in greater structure. The louvered opening is installed in each of their four 30' x 96'. disease incidence. To avoid potential controlled with a motor and high tunnels for a cost of $330 per crop loss, it is not surprising that some thermostat. tunnel, including the wiring. In the growers opt for fans. summer, the added air flow benefits In addition to an exhaust fan, Slack their mostly heirloom tomato crop. For winter production, when roll-up Hollow Farm uses four small fans However, for winter greens sides are buttoned down and doors hung from purlins to move air in a production they do not run these fans. firmly latched, gable-end vents may circular pattern in the 30' x 120' high The Zemelskys also use a gable-end be too small to do the job. In this tunnel. Commonly used in exhaust fan in four of their five high situation, an exhaust fan mounted greenhouses, these horizontal airflow tunnels.

48 – High Tunnels Heat stress Shade cloth is commonly used by Heat stress can be a problem for greenhouse growers to reduce the Heating plants growing in high tunnels that are interior temperature of the structure. inadequately vented. When leaf But shade cloth has less applicability High tunnels are normally defined as surface temperatures get too hot, to high tunnel growing. In the unheated greenhouses. Their primary photosynthesis and other metabolic Northeast, for many summer crops it sources of heat are solar energy and activities shut down. Plants close their will reduce light availability too the ambient heat of the earth. Farmers stomata and stop transpiring. If greatly, resulting in poor overall don’t use high tunnels to grow warm overheating is allowed to continue, growth and leggy plants. season crops significantly out of plants will grow poorly, and may season; instead, they use them to eventually die. Shade cloth does make sense for certain extend the normal season by a period species of cut flowers in high tunnels. In of several weeks. With the additional A high tunnel full of plants will stay southern Pennsylvania, the Cramers protection of internal row covers, much cooler than an empty one. effectively use shade cloth in one bay of adequate growing conditions for cold Transpiring plants release water into their Haygrove high tunnel to grow weather crops can be attained, even the air producing natural evaporative cool-loving (but long-season) lisianthus. during the winter months. cooling. This is also why misters work This material moderates high summer well to lower the temperature and why temperatures and reduces light For warm season crops such as trees, in addition to providing shade, diffusion, producing the elongated tomatoes and cucumbers, a standby cool down a city street. stems required by the market. heating unit can be brought into a high

In-Ground Radiant Heat In-ground, radiant heating tends to be a less energy-intensive approach than air heating for any structure, whether it is a building, greenhouse, or high tunnel. While relatively costly to install, in-ground systems, which circulate a heated fluid, consume less fuel than heating air, reducing fuel consumption and costs over time. Heating the root-zone stimulates seed germination and root development. In a radiant heating system, a water-antifreeze mixture is heated and circulated with small pumps through polyethylene tubing buried in the ground.

Slack Hollow Farm had been growing year-round in a high tunnel that had neither artificial heat nor electricity. But in their new 30' x 120' high tunnel, Seth Jacobs and Martha Johnson (with the assistance of a plumber) installed a radiant heating system that uses standard, off-the-shelf technology. Seth buried PEX tubing 18" deep, in rows 12" apart, using about a dozen 300' loops for the 30' x 120' tunnel. (Each loop consists of an outgoing and return stretch of tubing.) A 1:1 propylene glycol/water mixture, heated by an oil-fired hot water heater, circulates in the tubing. The heat spreads upward and outward in the soil at a 45-degree angle above the tubing. Once the heat is turned on, it takes about 10 to 12 hours to heat the soil 6" below the surface.

In designing their heating system, they were concerned that the antifreeze mixture circulating in the buried PEX tubing would be too hot for their crops. As a protective measure, they designed their system with all the “bells and whistles,” including dampening valves and return-flow mixing. These added features have proven unnecessary in their application in part because the heater itself can be turned down to 110°F.

For the first winter (2005-06), they chose 47°F as the target soil temperature at a 6" depth. Under the row covers at night, the lowest air temperature was 27°F. It took a single tank of oil (275 gallons, costing $500) to maintain this soil temperature. With the onset of longer days in mid-February, they were able to stop burning oil for the rest of the winter (even though temperatures were cold). They found that the soil 6" down could gain 5°F on a sunny day.

In 2005, before the heating system had been installed, they grew tomatoes in their high tunnel without heat. They warmed the soil to 70°F for their spring 2006 tomato crop, consuming three-quarters of a tank of oil in several weeks during that cold spring. In both years they started wholesaling tomatoes around July 11.

With just one year of experience with their in-ground heating system, it is too early for Seth and Martha to draw conclusions about the economic feasibility of this application. In order to cut fuel requirements, they plan to insulate the soil around the tunnel’s perimeter to a depth of at least 18". The temperature they will eventually choose for soil temperature in mid-spring for summer tomato production is still in question; they hope next year’s trials will help them come to an answer.

49 – High Tunnels tunnel as a temporary safeguard purview of this manual, one example inner covers daily. In contrast, while against extreme cold. But when of the use of in-ground heat is farming in Pennsylvania, Steve Moore growers install a permanent heating presented on page 50. Such a system used the heaviest weight fabrics for system, they begin to transform their has applications for growers who wish winter high tunnel production. He high tunnels into something more akin to minimally heat the soil in their appreciates its increased insulating to a greenhouse. structures just enough to prevent ability and durability and has come up freezing. with several streamlined systems for Nonetheless, farmers are constantly moving this material. experimenting, and there is much to be learned from their attempts to In Connecticut, the Zemelskys have create superior and cost-efficient used light- and mid-weight spun growing conditions. While the pros Interior Row polyester row cover to assist the crop and cons of conventional greenhouse in germination and protect their hardy heating systems are beyond the Covers greens for winter production. Andy Jones, in Burlington, Vermont, Floating row covers are commonly Relative Humidity and typically covers his winter greens with used to further protect plants from a single layer of mid-weight row Temperatures in a High cold weather within high tunnels. Tunnel cover, though on occasion he adds a They are either laid directly over second layer when “super cold” Water condenses on the inside plants or suspended over wire or pipe conditions are expected. At Slack surface of a high tunnel or hoops in the form of low tunnels. Hollow Farm in upstate New York, as greenhouse cover when the outside Some farmers use plastic film to many as three or four layers of a temperature drops below the dew create tunnels within tunnels. This is a medium-weight row cover protect point. Free moisture in the air good use for old greenhouse film, as spinach and other greens in the dead changes to a liquid state, the same long as it is not so degraded as to of the winter. way that dew is formed. When this prevent adequate light transmission. condensation drips, it can damage But plastic, whether new or used, At Slack Hollow, the covers are plants and promote disease. traps moisture and overheats the usually removed during the day. Seth Droplets of water on the plastic enclosed space more readily than Jacobs explains that, in order to take film reflect light away from the fabric row covers, and therefore must full advantage of solar gain, the tunnel. be opened or ventilated daily. ground needs to be exposed to

High relative humidity increases incoming sunlight so it warms up the Alternatively, spun-bonded synthetic groundmass, and then insulated from condensation. Evapotranspiration fabrics may be used. These include by plants contributes to the the cold air at night. This concentrates Remay, Typar, Agribon, Agrofabric, the stored heat from the sun in the humidity level. Ventilation or and Covertan. These row covers come heating can reduce moisture levels ground but eliminates the small layer in a various sizes and weights. of air under the cover. “On bitter cold, in the air. Weights range from 0.5 to 2 ounces very cloudy days we might leave High tunnel temperatures can be per square yard. Heavier materials some or all of the covers on during the measured for the air, soil, or plants. cost more and are less apt to tear. day, but we feel we should uncover Ventilation directly influences air Some are even rip-stop reinforced. whenever possible for maximum light temperature. Plant metabolism and The less the fabrics weigh the less on the plants, and heat gain in the growth processes affect plant cold protection they offer, but the soil,” he said. temperature. The intensity of solar more light they transmit. Because of radiation affects the temperature of this trade-off, the jury is out regarding Steve Moore follows the same logic the first inch or two of the soil, but the best weight row cover to choose as Seth Jacobs for row cover soil temperatures at greater depths under different conditions. management. On warm, sunny days, are constant. Plant scorching may he rolls back the covers, while on cold be influenced more by the intensity In Maine, Eliot Coleman prefers and cloudy days he tends to leave the of solar radiation than by air lighter weight materials as they allow covers on. However when there is a temperature. more light to penetrate and warm the string of two or more cloudy days, he soil during the day than heavier row finds it important to vent on “the best Adapted from Film Facts, covers which provide a few more days” as air movement helps prevent www.bpiagri.com/hort-luminance.htm degrees of frost protection. He does and control disease. not want to have to open and close

50 – High Tunnels In contrast, at the Intervale The tunnels within a tunnel averaged fourths of the way into the ground on Community Farm in Vermont, Andy approximately 18°F warmer than the edges of beds. Row covers may be Jones explained that their row cover outside temperatures. However, the suspended over these hoops just as management is less intensive. “We temperature difference for the five would be done in the field. wait to put them on until fairly late coldest nights was about 26°F. “This (around late November), but only plan is significant,” said Steve. “We want Attaching the row cover to the bows to remove them at harvest or for other the most protection on the coldest facilitates ventilation and access to chores.” nights.” beds for harvest and other horticultural tasks. For each bow, cut In a class of its own is Tufbell, one of Steve was puzzled by some of his a 2" piece of water pipe in half the heaviest, longest-lasting row cover temperature readings. He has recorded lengthwise. Using either a tek screw materials on the market. Made of an outside temperature of 17°F below or drywall screw, fasten one of these polyvinyl alcohol, its characteristics zero when the temperature in the inner small segments of pipe onto the top of are more conducive to winter grow tunnel was 17°F above zero. The each bow, sandwiching the horticulture than the more common lettuce growing there was perfectly polyethylene film between. (See spun polyester. It increases air and good and harvested for sale. He diagrams below.) To open these mini soil temperature by 5 to10°F and leaf attributes the survival of the lettuce to tunnels, the cover is flung over one temperature by 2 to 6°F, yet does not some of the freeze protection side. On a sunny day, the southern overheat in 90°F weather. It allows 92 mechanisms noted in the section on exposure is readily ventilated. to 95% light transmission. Only cold stress physiology and to the minimally degraded by sunlight and effects of super cooling. reinforced against rips, it lasts at least five years or longer if protected in Supporting Interior storage from mice and other nest Tunnels builders. It can also be sewn and The Zemelskys and other farmers washed. However, at 22.5 cents per protect their winter crops by laying square foot, it costs more than twelve their “floating” row covers directly on times as much as Argibon 19 (which newly seeded ground or over the top costs 1.6 cents per square foot). of growing crops without any

supporting structure. But some Over a period of several years, Steve growers have experienced a need to Moore experimented with a variety of support their covers. materials in two different configurations, using them as inner For low tunnels in the field, farmers grow tunnels on 5' wide beds and also often use hoops of 8 or 10 gauge as a 14' wide covering (half the galvanized steel wire to span their tunnel’s width). He tested the beds. Heavy gauge high tensile performance of used plastic livestock wire can also be used. (greenhouse film), Agribond products, Usually the hoops are about 2' tall and Typar, Agribell, Low-e (1/4 inch foil are placed 4' apart. However, for faced bubble wrap), thermal curtain winter production in high tunnels, material, Aluminet, and several Steve closes off the ends of his mini- several growers have noted that steel tunnels with half circles of twinwall others. hoops are not appropriate because polycarbonate or waste polyethylene they are not tall enough to prevent the film. The tunnels themselves are He found that used plastic was almost cover from touching the crop canopy. as good as very costly alternatives in covered with used greenhouse plastic Generally plant tissue that comes in cut to size. Each tunnel spans a single terms of thermal protection and heat direct contact with frozen row cover retention. In fact, he concluded that it 5' bed, and is about 3' tall. will become marred and may is the most economical and eventually die. environmental choice. He also found His tunnels within a high tunnel stay 15 to 20°F warmer than minimum that covering half of the high tunnel Steve Moore makes hoops with 8 foot (14' width in a 30' house) performed outside temperatures in winter. In lengths of used polypropylene water sunny weather, he finds it essential to better than covering one 5' bed at a pipe (3/4" to 1-1/4" diameter). The time, regardless of the materials used. roll or pull up the plastic to reduce pipe ends of the 8' lengths are placed unwanted heat within the low tunnels. over 18-inch pins pushed three-

51 – High Tunnels The plastic is also pushed out of the for roll-up sides—spanning the length way for weeding, watering, and of the high tunnel, to make a roll-up harvesting. for the row cover. This roll-up is outfitted with a hand crank. Some of his 30' wide high tunnels are laid out with a center aisle flanked on John Biernbaum created a row cover either side by beds running laterally suspension frame almost 4' high for across the tunnel (see “Interior taller crops in his latest teaching and Tunnel Layout” on page 57). Using demonstration high tunnel at this configuration, Steve is able to Michigan State University. (See cover half of the cropping area (one Diagram 12.) The tunnel itself is 30' side of the entire tunnel) with a single wide with 25' long lateral beds. Aisles large sheet of row cover. on both sides in the colder and wetter For horizontals, two 10' pieces of 1/2" edges conserve the center area for conduit, each with a 90 degree bend To suspend the row cover above the growing. The design uses a horizontal on one end, cover 18' of the 25' bed crops, Steve uses a long, rail-like member for every bow and bed, both length. A piece of 3/4" conduit in the hoop. He finds the larger, wider of which are 4' on center. center spans the remaining 7'. The tunnel within the tunnel to be more ends of the 1/2" conduit fit inside of effective in retaining heat than the the 3/4" conduit. The 5' vertical smaller, single 5' bed inner tunnels. support pieces (one at each end of He has even created a roll-up horizontals) are made of 10' long 3/4" mechanism for convenient venting conduit cut in half. They are driven and re-covering. about 20" into the ground. The bend of the horizontal conduit raises the His framework for suspending the height a bit more. floating row cover is made of 1/2" or 3/4" thinwall electrical conduit. These metal pipes are spaced 4' on center to line up with the high tunnel bows. Steve bends one end of this metal pipe to a 90 degree angle to support the framework at a height of 30". He supports the middle of the 14' laterals with a piece of PVC pipe and uses a 2" x 4" to attach each metal conduit to a bow. Row cover can be laid loosely over this framework and scrunched up against the sidewall to open up the growing beds. Alternatively, Steve uses a swedged pipe—the kind used

52 – High Tunnels Freeze Damage in Plants There are three stages of freezing. As it gets colder, first the water in the soil freezes. Next, the water between a plant’s cells freezes. Finally, water inside a plant’s cells freezes, usually killing the plant.

Freezing of Water in the Soil Water freezes at 0°C (32°F), yet, in the soil, dissolved solids lower the freezing point of water. When soil water freezes, it actually leaves particles and solutes behind.

In the process of freezing, water expands. While this can cause physical damage to the plant root, at times root cells are able to withstand pressures of up to 1000 atmospheres. This ability to withstand pressure varies seasonally and has been shown to increase with cold hardening. Freeze hardening is not completely understood. It is believed that the seasonal storage of sugars, sugar alcohols, and proteins within the cell aids in lowering its freezing point.

In addition to increased pressure, the frozen ground also prevents plants from taking up water. If they cannot replenish the water they lose through transpiration and other processes, they will die of desiccation (drying out). Winter wind can rob water from plant tissues, exacerbating the requirement for water. Both high tunnels and greenhouses are very effective in protecting against this type of desiccation.

Freezing of Inter-Cellular Water When water changes phase (i.e., from liquid to solid), it releases significant amounts of energy. Freezing water literally releases heat!

In addition, in freezing temperatures, plants actually expel water from their cells into intercellular spaces. This increases the solutes within the cell, lowering the freezing point of cellular water and protecting the cells. This protective action can keep a plant from structural damage, even if it looks wilted or appears to be frozen.

Freezing of Intra-Cellular Water Under most circumstances, when the temperature gets cold enough to freeze the water inside a plant’s cells, the plant dies. It is ice crystal formation that kills the plant and not freezing per se. Rapid freezing of cells can occur without ice formation. Supercooling can also alter the freezing point, but this is a poorly understood process.

In Walking to Spring, their book about high tunnels on their farm about 100 miles southeast of Louisville, Kentucky, Paul and Alison Wiediger recommend keeping high tunnel plants on the dry side in the cooler months. “We don’t let them wilt, but we don’t keep them really turgid either…Dry conditions allow plants to accumulate more sugars in their cells, and acclimatize the cells to the cold.”

“We can go in the on a sub-freezing morning (say below 20°F) and all the plants look dead—lying on the ground, you know the frozen look! But by 10 AM or so, especially if the sun is out, they are all upright and beautiful again. It breaks your heart the first time you see it, but it invokes wonder two or three hours later.”

“Last year we had the soil at a good moisture level in mid-November and we didn’t need to water until February…When we need to water [in the winter], we watch the weather forecast for a window of several days and nights above freezing. We water on the first day of that window, so that by the time the freezing temperature returns, the plants have adjusted to the extra water.”

53 – High Tunnels

Soil and Crop Management

Monitoring Soil Health Because of this intensity, high tunnel Soil Management A good monitoring program evaluates soils benefit from relatively high the physical and biological applications of compost, fertilizer and Most high tunnel growers produce composition of your soil as well as its other soil amendments. Similarly, their crops in the soil on which the chemical makeup. large applications of organic matter tunnel rests; therefore, the quality of are also beneficial. the soil under your tunnel will be Several important indicators of soil critical to your success. Given that physical health are easy to monitor. Farmers approach nutrient you will spend a good deal of money To determine if your soil is management in high tunnels in a to construct a premium growing compacted, for instance, you can use a variety of ways, many of which are structure, it makes sense to complete penetrometer, a tool that measures similar to their field practices. One the job by making certain the soil resistance to penetration. Although notable absence from high tunnels is environment is also a superior one. these devices are expensive, they can the practice of cover cropping, even sometimes be borrowed from your on farms that employ cover crops in A coarsely textured, well-drained soil local Extension office. You may make their fields. Farmers have offered is best for high tunnel production. an effective penetrometer at home by several reasons for the lack of interest Clays, because they drain and warm putting a simple handle on a straight in cover cropping in high tunnels: relatively slowly and have a tendency piece of rebar. The tip should be first, there is no risk of erosion inside to accumulate salts, are the least sharpened to a dull point. You should a tunnel; second, space is at a desirable soils for high tunnels. (See be able to push it at least 12 inches premium; and third, windows of time “Salinization” on page 56.) However, down into the soil before encountering for cover cropping are minimal, growers have been able to make do resistance. particularly for farmers who use their with a wide variety of soils, amending tunnels year-round. Some cover crops and improving them over time. You can also check plant rooting could potentially serve as over- depth. If you observe plant roots to be wintering habitat for pest species. The structure of the soil in the growing horizontally at a shallow relatively small space under a tunnel depth, then the soil is probably too Many farmers rely heavily on can be dramatically altered. The compacted for good root penetration compost as the foundation of their addition of substantial amounts of or water drainage, and should be fertility programs. A balanced compost or leaf litter will increase the loosened by some form of tillage. compost added to a good soil can organic matter in the soil, thereby When preparing the soil for planting provide the range of nutrients required increasing the soil’s capacity to or when removing crop debris, take for crop development, and some provide oxygen, water, and nutrients the time to determine if earthworms farmers depend upon it exclusively for to the crop. are present and at what level. fertility. Too much of a good thing can create its own problems, however. To lighten heavy clay soils, organic Traditional chemical analyses are as Using too much compost is not only matter can be added in a variety of important in tunnels as they are in the expensive; it can also lead to the forms, besides finished compost. For field. Nutrient and organic matter build-up of salts and outbreaks of example, aged wood shaving with levels, soil pH, and electrical root-feeding arthropods such as tiny leaves or a small amount of manure or conductivity (salts) should all be symphylans. another organic nitrogen source can measured periodically. improve the structure of a heavy soil. Several farmers reported adding large Avoid fresh wood shavings as they Adding Nutrients amounts of compost to a new high will tie up soil nitrogen. John High tunnel production is intensive, tunnel, and then adding modest levels Biernbaum improves the soils in his with faster growth than typically thereafter. For a new tunnel at Slack high tunnels with significant amounts found in field production. In some Hollow Farm, compost was added at of animal bedding from weekend cases, three or even many more the rate of 10 tons per acre. The livestock shows on campus. This successions of crops are grown in a Blomgrens also load up at the onset. bedding has a low concentration of tunnel during a single year. (Greens Then, before each new crop, they manure. growers can produce as many as eight spread just five gallons of compost crops per year in the Northeast.) per 40 square foot bed—a layer of less

54 – High Tunnels than an eighth of an inch. They add (A persistent herbicide called Nitrate Uptake in Low this compost to enhance microbial chlorpyralid has contaminated Light Greens activity, nutrient availability, and soil composts containing lawn clippings water-holding capacity. These and other materials.) Farmers can It has been well documented that quantities improve the soil’s structure, request test results from commercial the ingestion of excessive nitrates but don’t affect soil texture. Compost composters or submit compost from our diet and water can be must be free of viable weed seed. samples to laboratory services like detrimental to human health, Dairy One. especially in the very young. The Composted manures typically have an European Union has set limits for excess of phosphorus in relation to Some farmers manage soil fertility nitrate levels in greens. The United nitrogen. If compost is applied at a more strictly by the numbers and with States has not yet taken action. rate designed to meet crop nitrogen less bulky materials. Fertigation, with Farmers should be aware of this needs, phosphorus will be soluble fertilizers injected into a drip food safety issue and act oversupplied. Farmers who have irrigation system, is the basic program accordingly in order to produce recognized this problem are reducing employed by many farmers who healthy food. their compost applications and operate in controlled or managed Greens grown in low light (off- applying alternative sources of environments, such as high tunnels season, winter production) have nitrogen. When determining fertilizer and greenhouses. Growers, like Keith greater potential to accumulate rates, they are sure to credit the Cramer at Cramer’s Posie Patch in unhealthy nitrate levels. Plants can compost for the nutrients it has Pennsylvania, incorporate a chemical take up nitrates in excess of their supplied. fertilizer into the soil prior to bed needs. There are a number of preparation. Steve Groff, also in management strategies that can When soils are cool in the spring, Lancaster County, Pennsylvania, also moderate nitrate uptake and microorganisms are not converting uses his drip irrigation system to improve its assimilation, giving the nitrogen to an available form fast supply his high tunnel tomato crop’s end result of healthy greens with enough to sustain good plant growth. nutrient needs. low levels of nitrates. This is the time to consider adding a soluble nitrogen source, such as Like fertigation, foliar feeding makes The range of suggested practices Chilean nitrate (guano). soluble nutrients immediately includes: available. Two farmers in this project • Harvest greens later in the day. Just as periodic soil testing is foliar feed Epsom salts, kelp, and fish advisable, it is also wise to have products respectively. This practice • Do not sell older, more mature compost tested for nutrient can be used with a variety of leaves. availability, pH, and the presence of micronutrients as well. • Supply adequate soil moisture. substances like salts or toxics that could be detrimental to crops. • Maintain soil pH on the high side of the normal range. • Provide balanced soil fertility. • Grow in warmer temperatures. • Select cultivars that better Day Length Affects Flowering assimilate nitrates (when this characteristic is known). If you extend the season at either end to achieve earlier or later harvest dates, some cut flowers will not perform as anticipated. Plant physiologist Chris • Use legume-based compost as a Wien, a Cornell professor, realized that day length was the culprit when his source of nitrogen. several of season extension trials failed. He attempted to get sunflowers to bloom in the spring rather than summer and he started Rudbeckia hirta (Black-eyed Susan) late to get fall flowers. To prevent mishaps, he suggests experimenting on a small scale before you decide to grow a flower cultivar off-season. He found that seed catalogs are not always correct on this point. (See “Daylength affects rudbeckias, sunflowers,” June 2006 Growing for Market.)

55 – High Tunnels Salinization Like irrigated lands in arid climates, high tunnels may be vulnerable to the accumulation of salts. If allowed to build up, salts may cause damage to crops. If soils within the high tunnel are well-drained, irrigation water may leach some of the salts through the soil profile, as occurs with adequate, regular precipitation outside. However, if the soil is poorly drained, accumulated salts will actually be brought up to the surface when soil moisture evaporates.

The application of synthetic fertilizers, animal manures, or manure-based compost (all with significant salts) can result in the build up of salts over time in high tunnel soil. Sodium chloride—table salt—is not the only problematic salt in soil. At excess levels, other salts also cause drought-like stress, interfere with seed germination, and inhibit plant growth. Plants with higher drought tolerance typically handle increased soil salt concentrations better than more drought susceptible plants. Nutrient uptake and other metabolic processes can also be disturbed by soil salinity.

In addition to directly affecting the plants, elevated salinity levels have been anecdotally associated with damaging outbreaks of symphylans, tiny arthropod pests (also known as garden centipedes) that feed on plant rootlets and root hairs. “The effects of high soil salts aren’t pretty on plants or income,” says Steve Moore, speaking from personal experience.

Salt stress can mimic the symptoms of drought stress, nutrient deficiency, and root rots caused by soil-borne pathogens. Thus, it makes sense to pursue a proper diagnosis of the problem. One way to test for salinity is with an electrical conductivity (EC) meter (available for under $100). (See “Ben Meadows” and “Pike Agri-Lab” on page xx.) Electrical conductivity is a measure of the ability of a solution to transmit an electrical current. The higher the salt level, the greater the current. EC readings are usually given in deciSiemens per meter (dS/m). In general, readings over 1 dS/m may indicate problems for some fruits and vegetables. When comparing your EC values to those that are published, be sure you are using equivalent sampling procedures. Otherwise, you will not be comparing “apples to apples.”

Salinity Tolerance of Common Vegetables Grown in Utah Threshold 10% 25% 50% Crop value yield loss yield loss yield loss EC (dS/m) EC (dS/m) EC (dS/m) EC (dS/m) Asparagus 5.0 8.0 11.0 13.0 Beans 1.0 1.5 2.3 3.6 Beets 5.3 8.0 10.0 12.0 Broccoli 2.7 3.5 5.5 8.2 Cabbage 1.8 2.8 4.4 7.0 Cantaloupe 2.2 3.6 5.7 9.1 Carrot 1.0 1.7 2.8 4.6 Cauliflower 2.7 3.5 4.7 5.9 Celery 1.8 3.5 5.8 10.1 Corn, Sweet 1.7 2.5 4.0 6.0 Cucumber 2.5 3.3 4.4 6.3 Lettuce 1.3 2.1 3.2 5.2 Onion 1.2 1.8 2.8 4.3 Peas 0.9 2.0 3.7 6.5 Pepper, Bell 1.3 2.2 3.3 5.1 Potato 1.7 2.5 3.8 5.9 Radish 1.2 2.0 3.0 8.0 Spinach 3.7 5.5 7.0 8.0 Squash/pumpkins 3.9 4.9 5.9 7.9 Sweet Potato 1.5 2.4 3.8 6.0 Tomato 2.5 3.5 5.0 7.6 Turnips 0.9 1.9 3.1 4.9 Watermelon 2.0 2.5 3.5 4.5 (Continued on next page.)

56 – High Tunnels “Salinization” continued from page 56. EC is the electric conductivity of the extract using a water saturated paste solution. Note the reduction of yield as a function of increased salts. From Utah State University Extension, http://extension.usu.edu/files/agpubs/salini.htm.

The following strategies can help reduce soil salinity in high tunnels: • Provide adequate soil drainage through natural means (locating tunnels on well-drained soils) or improve soil drainage through artificial means (drainage tiles or pipes). • Allow the soil to dry and then scrape off a top layer of soil and salts. Add more soil as needed. • Flush out the salts periodically. This can be done either by removing the cover or by flooding the high tunnel during the off-season. This second approach requires a great deal of irrigation water, however. When changing the poly film every four years, consider leaving the tunnel uncovered and exposed to natural precipitation for a period of time. • Reduce the amount of salt-forming fertilizers and use vegetable-based compost containing legumes.

In caterpillar and multi-bay tunnels such as Haygroves, which are uncovered during the off-season, salt build-up is eliminated because precipitation flushes away the excess.

Adapted in part from “Salt Tolerance of Plants”, Alberta Government Agriculture, Food, and Rural Development, www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex3303.

production and accessibility. Farmers which longitudinal rows can provide Interior Tunnel strive to maximize the growing area via large gable end vents and doors. since space is costly and limited, Layout while allowing ready access to all A long row configuration has other portions of the tunnel. advantages. It makes it easier to The growing space in a high tunnel is utilize inner row covers on a bed-by- often broken up into beds. Some Longitudinal Beds bed basis. Fewer connections are farmers create raised beds slightly or Setting up the rows or beds along the needed for T tape. Long rows substantially higher than the long axis of the tunnel is the most facilitate the use of tractor-driven surrounding pathways by adding typical high tunnel layout, and is equipment. They can also make for a compost and/or soil. Beds can be especially suited to growing tomatoes simpler system, especially if only one made manually with hand tools, or or other trellised or staked single row or very few different crops are grown mechanically with equipment such as crops (see Diagram 13). Tomatoes in the tunnel. Long rows also allow a roto-tillers or bed shapers. A good benefit from goods air circulation, the easier use of overhead grow tunnel layout optimizes crop troughs.

Plants grown along the perimeter of a tunnel may exhibit an “edge effect,” with poorer growth common closest to the side walls because temperatures are lower there. Wider high tunnels have less of this chillier growing space relative to their overall area than narrower high tunnels, and this should be considered when determining high tunnel size. Some farmers reserve this space for especially hardy crops. For example, the Zemelskys grow hardy pea tendrils around tunnel perimeters in winter.

57 – High Tunnels Lateral Beds many more short beds. A 30' x 144' Orienting beds laterally across the high tunnel with a center aisle and Crop width of a high tunnel is another beds spaced 4 feet apart has as many Establishment solution to the twin challenges of as 70 individual beds. access and crop optimization (see diagram below). This layout utilizes a For tunnels with an East-West Seedbed Preparation center aisle, with beds running orientation (which is best for winter High tunnel growers use both flat and perpendicular to the aisle. Even in a growing), configuring lateral North- raised beds, and some use both in 30' wide tunnel, a worker never has South beds will result in less shading different situations. Raised beds are more than 14' to go from the aisle to of crops. When using interior covers, especially beneficial to spring crops the far end of a bed. For harvesting as the lateral bed layout enables the because they improve soil aeration well as for transplanting, this kind of farmer to cover the entire tunnel with and facilitate water drainage, resulting accessibility means a lot. Using this just two pieces of row cover, one to in warmer soils, increased microbial configuration, the farmer can afford to the right of the central aisle, and one activity and nutrient availability, and make the single, center aisle to the left. Steve Moore has designed enhanced root development. generously wide without worrying a simple rail system that supports the about squandering prime growing row cover over each half of the There are many ways to prepare the space. In fact, this layout provides tunnel’s beds, making covering and seedbed within a high tunnel. The slightly more growing space than one uncovering a relatively quick process spectrum of possibilities ranges from divided into longitudinal beds. (see page 52 for the “tunnel within a hand tools to small-scale, tractor- tunnel” discussion). This approach powered field equipment. Self- The central aisle makes it easier to saves labor and retains heat better. propelled roto-tillers are an move materials in and product out. intermediate option between tractors Worker movement is also more Lateral beds can also be laid out and hand tools. As long as a tractor efficient. Flats for transplanting and across the entire structure, with aisles can be found that fits inside the harvest lugs can be put in the lateral situated along the long sides of the structure, equipment such as chisel pathways so that workers don’t have tunnel. This layout makes sense under plows, spaders, tillers, bed shapers, to walk over them when coming and cold growing conditions, as the edges and mulch layers can be used in high going. A monorail or overhead tram offer the least protected microclimate, tunnels. Equipment manufacturers can even be installed to mechanically but has a drawback in that it situates have begun to make specialized move materials down the center. The aisles where there is the least amount tunnel-scale equipment. Ample central aisle layout simplifies the use of headroom in a high tunnel. Slack ventilation will make the use of diesel of hoses. A drawback for those using Hollow Farm is currently using a and gasoline engines in high tunnels a drip irrigation is that many more drip variation on this layout. safer and more tolerable task. starts are required because there are so Winter growing pioneer Eliot Coleman has devised a market garden production system relying solely on hand tools, some of which he designed. After adding soil amendments, he loosens the soil with a broad fork (a 24'' wide fork that harnesses body weight rather than muscle power to loosen soil without inverting it). Next, the beds are leveled, and debris, roots and rocks are removed using an extra-wide bed preparation rake. Short tubular fingers (which can be purchased with the rake) can be placed over selected rake tines to individually mark rows or a grid pattern for seeding or transplanting. (See “Johnny’s Selected Seeds” on page 69.)

58 – High Tunnels Seeding and transplanting However, plugs bring the risk of needs are correspondingly greater. Because of the tight spacing in a high thrips and other pest outbreaks that During the spring and summer, when tunnel, seeding and transplanting is can cause difficulties in the entire high tunnel crops are growing usually done manually. Northern house or, worse, the multiple houses especially fast, their demand for water producers use transplants for long- into which the starts from the is quite high. It is not uncommon for lived, warm weather vegetables and greenhouse are transplanted. high tunnel tomato and cucumber for most cut flower species (other than growers to irrigate every day during those grown from vegetative Direct seeding is not the only way to the height of summer. Water needs structures like bulbs or corms). In start salad and braising mix crops like shrink as the days become shorter and contrast, direct seeding is the popular Asian greens, lettuces, chards, bok colder. By winter, very little irrigation method for starting short season, more choys, and other relatively quick- is required. Over the course of the closely spaced crops like salad greens growing greens. For greens following year, and depending upon the growth and spinach. tomatoes, Ted Blomgren finds that stage of a crop, growers will adjust transplanting allows him to keep the the amount of water provided. There are a variety of push seeders on tomatoes in the ground three weeks the market costing between $100 and longer. Then, within days of removing Drip irrigation is a common method $500 and up. Earthway Company a tomato planting in the fall, the for providing water to plants in high manufactures one of the least newly transplanted winter crops are tunnels. High tunnel systems are expensive one-row seeders on the well-established for his winter CSA. identical to those used in the field. market. Several of these light-weight Drip tape delivers water without plastic seeders can be attached in a Additional tomato yields, in his view, wetting foliage. Preventing prolonged gang and pushed by hand. The more more than offset the cost of soil mix leaf wetness, which contributes to durable old Planet Junior seeders are and labor for tending flats of seedlings crop disease, is especially important still available from used equipment in the greenhouse. This approach also in warm season crops. Drip systems dealers (see “Tools” on page 70) and reduces the risk of germination failure are often automated with a timer to on eBay. In addition, Planet Junior and gives him the plant stands for ensure regular watering. Using production has resumed. Johnny’s sells which he is looking. multiple drip lines on a bed will also a European push seeder modeled after provide for the water needs of the Planet Junior (though welded rather For these mid-fall plantings, Ted sows multiple rows of crops. Drawbacks to than cast) for half the price of the new up to five seeds per cell in 98-cell drip irrigation include the cost and $500-plus version. One-, four-, and trays. This seeding yields clumps of amount of plastic involved and the six-row pin-point seeders are another plants that are set six inches apart fact that drip tape interferes with crop mainstay of tunnel growers. Designed within and between rows in 3' wide cultivation. for seeding salad crops in close-row high tunnel beds. Arugula, kales, spacing, they create uniform plantings Asian brassica greens, chard, and Red Direct seeded plantings, especially the that do not need to be thinned. Salad Bowl (his favorite lettuce greens and root crops that are closely cultivar for winter growing) are spaced, may be less suited to drip Crops that are transplanted in the field among the crops he grows this way. irrigation. For these applications, are also usually transplanted in the overhead sprinklers have a place in high tunnel, including tomatoes, As a rule, the way to boost the high tunnels. To break the disease peppers, eggplants, cucumbers, economic return from the high tunnel cycle, watering should be done in the summer squashes, melons, basil, and investment is to keep its growing morning to allow plants to dry before other herbs. Early season transplants space well utilized. Intercropping and evening. are usually started in a heated succession cropping are strategies for greenhouse (or in compost-heated hot making optimal use of space. An irrigation system can be devised beds within the high tunnels), and Interplanting scallions or fast-growing that uses either drip tape or overhead transplanted into the unheated high greens with slow-growing tomatoes, sprinklers, depending on the crop tunnel when the climate becomes for example, are ways to boost rotation in the high tunnel. Low conducive to their growth. economic returns from a high tunnel. pressure, small volume micro sprinklers are available that can run Most cut flowers are also Watering off the same main trunk as drip tape, transplanted. For some slow-growing Careful attention should be paid to making the conversion of an irrigation or hard-to-germinate species, irrigation in high tunnels. The plant system simple. New irrigation purchasing plugs from a nursery can canopy in a high tunnel is usually technology and products are save on labor and fuel costs. greater than it is in the field, and water becoming available all the time.

59 – High Tunnels

Pest Management

weeds. Hand hoes are particularly thread stage, use a propane flamer or Weed well suited to the intimate very shallow tillage with a stirrup hoe environment of a high tunnel. If used to destroy them. Take care not to Management when weeds are very small, hand hoes bring up more weed seeds from lower provide fast and effective weed in the soil profile when tilling. No farmer wants to spend precious control. Often, a single well-timed time combating weeds. Besides hoeing will produce a weed-free salad Carrying out stale seed bedding competing with crop plants for light, or cut flower crop. If given a weed- requires a several week break in the nutrients and water, weeds may serve free start and good growing cropping cycle. Because high tunnels as reservoirs for plant pathogens and conditions, these fast-growing crops are an expensive horticultural arthropod pests such as thrips, aphids should out-compete weeds. Hand hoes environment compared to open fields, and spider mites. These pests may are available in several configurations it is worth making this sacrifice to also find crop plants attractive. They (e.g., oscillating stirrup hoes, push- optimize growing conditions before often act as plant disease vectors, too. pull hoes and collinear hoes), and in weed pressure gets out of hand. The Weeds can also turn harvesting and sizes ranging from 3" to 12" wide. farmer must be an effective manager processing of certain crops like salad (See “Tools” section on page 70.) to take advantage of the narrow greens into an aggravating task. For window available in the crop these reasons, and because weeds that Stale Seed Bedding sequence for stale seed bedding. produce seeds will cause trouble later, Stale seed bedding is a versatile allowing weeds to grow is not a good approach that allows the grower to nip Another weed problem that growers idea. weed pressure in the bud. The idea is may face is the encroachment of

to encourage weed seeds to germinate perimeter vegetation, including quack Weed problems are compounded by and then to kill the emerging weed grass, into a tunnel. If regular mowing the enhanced microclimate of a high seedlings before they can take hold. is not sufficient, try landscape fabric tunnel. Its longer season and more This process is repeated up to several as a weed barrier. It should be well moderate cold season conditions times in rapid succession typically secured on bare ground along the provide a perfect habitat for many before the crop itself is planted. outside perimeter of the tunnel. Mow weeds. For instance, chickweed, a right up to it. A foot wide barrier of winter annual that flourishes under the As a new grower, David Zemelsky at landscape fabric on a tunnel’s inner mild winter conditions present inside Star Light Gardens in Connecticut perimeter is also an option. a greenhouse, can cause serious experienced an incremental build up difficulties for winter salad greens of the weed seedbank in his high Mulching growers. tunnel beds. Weediness ultimately Mulching with organic materials such

impacted yields in his greens. As a as rye or oat straw is an option for Whether inside a high tunnel or in the result of his struggle with weeds, he weed prevention in crop beds for field, reducing the weed seedbank in has become a believer in the value of tomatoes and the like, especially if the soil is a key principle in weed stale seed bedding. additional soil warming is not management. Unless preventative essential. Straw retains soil moisture measures are taken, high levels of As an example, consider stale seed and eventually breaks down into soil weed seeds are likely to translate into bedding for a winter crop of baby organic matter, with no disposal high weed pressure. The good news is brassica greens following tomatoes. needed. that within the finite boundaries of a First rip out the tomato vines, add soil high tunnel, farmers have found it amendments, and renovate the bed. To However, straw left in place possible with vigilance and timeliness avoid bringing up new weed seeds, do indefinitely can attract mice and other to regain the upper hand on weeds, not invert the soil! Instead, loosen the unwanted rodents. Organic mulches even after they have raged out of bed with a broad fork as one of can exacerbate slug infestations. control. several ways to achieve this end. After Straw mulch may also interfere with

the bed is readied for planting, firm it the functioning of precision seeders. High tunnel growers use hand hoes, and, if necessary, irrigate to encourage Andy Jones of Intervale Community stale seedbed techniques, and plastic weed seeds to sprout. When the new Farm experienced this problem when and organic mulches to manage their weed seedlings are still in the white he direct seeded greens after a straw-

60 – High Tunnels mulched tomato crop. He warns, landscape fabric for use with other bacterial canker and Verticillium wilt “Even a fine toothed landscape rake crops that do not host the same in tomatoes; powdery mildew in leaves behind enough bits to give the diseases. tomatoes, cucumbers, squashes, late planter (and me) conniptions.” season lettuces, and flowers; Chris Lincoln at New Minglewood Alternaria leaf spot in brassicas; Straw has another role between beds. Farm used 6' wide pieces of landscape Fusarium root rot in lisianthus; and Ted and Jan Blomgren at Windflower fabric to cover the ground in and leaf spot in Bells of Ireland, among Farm use straw to prevent weeds between four 10' x 100' walk-in others. between beds, whether they are tomato tunnels. With 2' between each mulched with plastic or left bare. tunnel and two rows within each Tomato growers should pay careful tunnel spaced 6' apart, he was able to attention to variety selection. Disease- For long-lived crops such as tomatoes, plant the tomato transplants at the resistant varieties with good yields peppers, melons, and cucumbers, intersection where one piece of fabric and eating qualities are increasingly many farmers opt for synthetic ended and the next started. available. Where the incidence of soil- mulches to stymie weeds and heat the borne diseases has been high, some soil. Their use in tunnels is no growers have turned to grafting. Mike different from field situations. Black Collins, who grows greenhouse (or other colored) plastic can be tomatoes in southern Vermont, grafts applied with a mulch layer or laid Managing Diseases ‘Buffalo’ scions onto a vigorous and down by hand. U-shaped ground disease-resistant rootstock. The staples—6" galvanized steel or plastic in High Tunnels practice increases his cost of staples—are one way to pin down this production but it also provides him plastic film. Many growers have chosen high with superior yields of excellent tunnels, in part, because they offer tasting fruit. After amending the soil in preparation protection against the diseases their for planting, Tim and Janet Taylor, at field crops encounter. Septoria leaf A preventative approach to disease Crossroads Farm in Vermont, cover blight, (one of the most troublesome management is the best strategy. In the ground in their high tunnels from diseases of tomatoes in New York general, it is best to take steps to wall to wall with a solid sheet of State), for example, is virtually enhance air movement and reduce heavy black plastic mulch. Steve unheard of in high tunnels. Crops relative humidity. The following Groff, at Cedar Grove Farm in inside high tunnels usually experience tactics are also recommended: much shorter periods of leaf wetness Pennsylvania, plants tomatoes into • Provide adequate plant-to-plant than crops in the field. Diseases will heavy-duty landscape fabric. At spacing to avoid excessive shading not occur in the absence of the Cramer’s Posie Patch, white plastic and enhance air circulation. environmental conditions necessary mulch does double duty—it • Select disease-resistant varieties. suppresses weeds and cools the soil for the existence of the pathogen that • Maintain a pest-free environment. for cool season cut flowers. causes them. Keep high tunnels free of the

weeds that harbor diseases and the One way to make planting holes in Nevertheless, disease is not eliminated insects that transmit them. landscape fabric is to use a propane in high tunnels. Leaf mold (Fulvia torch. Minor (or major) mishaps can fulva) on tomatoes, for example, has • Practice good sanitation. Remove occur, as the material is flammable, become increasingly commonplace. diseased crop residues, and sanitize and care should be used. Cutting an The danger of an infestation is highest mulches and trellises. “X” in the fabric is another method. when airflow inside the tunnel is low • Provide the nutrients and water Both approaches have their and relative humidity is high. necessary for optimal crop growth. Selecting resistant varieties, reducing proponents and detractors. • Utilize a good crop rotation. plant populations, increasing tunnel ventilation (by adding gable-end • In the absence of a winter crop, Plastic mulch can harbor plant open the tunnel so that disease pathogens, some of which may vents, etc.) and promoting improved air circulation inside the tunnel (e.g., spores can be killed by winter overwinter in folds of the material so temperatures. its reuse can be risky. The bacterium adding fans) are each parts of a potential solution to the problem. that causes Bacterial Canker in tomatoes, for example, is thought to Growers have reported other disease overwinter on tomato stakes and mulches. Where possible, rotate problems as well. These include

61 – High Tunnels After a few weeks, we took a minute Remove weak and injured plants. Just Ecological Insect together to look at the plants. We as wolves following deer herds will found that only the plants in prepared, cull the weak and old, insect pests and Management in sterilized media were hosting the plant disease organisms will hone-in High Tunnels aphids while those in our compost on those plants that are best not left in were free of aphids. the gene pool. As farmers, we select By Steve Moore for traits such as yield, climatic Encourage Beneficial adaptability, or taste. Yet we often Insect pests generally cause less Insects and Other ignore pest susceptibility traits by damage in high tunnels than they do substituting chemical controls instead. in the field, in part, because the crops Arthropods According to the old adage, “diversity inside are growing at a time when Know, Scout, and Monitor pests are less active. The tunnel itself leads to stability,” we are aiming for a balance between the “good” and Know your insect neighbors at all functions as a barrier to insect pests, stages of their life cycles. If you have at least until temperatures warm to the “bad” organisms. Eliminating all of the bad (pest) organisms invites ever looked at the larval stage of a point that the tunnel sides are open ladybug, you will agree that they look much of the time. Nevertheless, trouble, and in the absence of beneficial insects, pests can quickly anything but helpful. Yet even in this insects in high tunnels can cause stage, they are aggressive pest economic losses. Aphids and thrips, become a problem. controllers. A good insect both of which have fairly broad host identification book (see page 74) that ranges, can be particularly Avoid synthetic pesticides and use natural and botanical pesticides shows the various insect life stages troublesome in high tunnels. And high and lists their primary food sources is tunnels can also harbor pests and sparingly. As a general rule, beneficial insects are more sensitive to pesticides indispensable. allow them to hatch earlier than outside. than pests. Synthetic chemicals often have long residual effects. You will be Careful scouting will enable you to discover insects and diseases (and Years of experience have proven the amazed at the number of beneficial insects indigenous to your greenhouse estimate their incidence) before it is effectiveness and shortcomings of a too late to manage them. In scouting, biologically-based high tunnel pest when you don’t suppress them. typically 2% of the plants should be control program. Here are some observed. Over time, you will become important considerations to achieve Don’t bring in plants that may have pests or pesticide residues. We familiar with which insects like which good control of potential “pests.” plants and where to look for them. For learned this the hard way by accidentally bringing in tomato plants example, whiteflies “like” the third set Develop Healthy Soil sprayed with the insecticide, Lannate of leaves down on tomato plants. Healthy, balanced soil is the single (active ingredient methomyl). The most important factor in attaining long-lasting residues of this Sticky cards are a well-accepted and healthy plants. Our most important insecticide are lethal to most inexpensive monitoring tool. Yellow amendment is well-made biologically beneficial insects for 8 to 12 weeks. cards attract most insect pests, active compost. We also use this Because the Lannate-treated tomatoes including whiteflies and aphids, while medium for our flats and transplants. wiped out beneficial populations that blue cards attract thrips. Attach these We avoid excess nitrogen as it came in contact with them, we were cards to posts or strings with compounds pest and disease problems unable to introduce beneficial insects clothespins. Write the date on the card and it makes the food less nutritious. in a timely fashion. Although we so it serves as a record of pest activity.

applied other strategies, the aphids Each card can be used for an entire A research project reinforced my almost got ahead of us. (See “Koppert month. For the first week, remove the intuition that healthy soil leads to Side Effect Database” on page 74.) protective paper from one half of one healthy plants. As part of a three-year side of the card. The next week, place beneficial insect project, we reared Another high tunnel grower reports clear plastic wrap over the used beneficials in our own greenhouse. that pests come along with every section and remove the protective We acquired aphid-infested tomato shipment of plugs. For example, cover from another half of the card. plants, re-potted several of them, and fungus gnats arrived with lisianthus The next week, continue on the back placed them in insect cages. A plugs almost every time they order of the sticky card. At the end of the colleague who was counting the them. four-week period, the card provides a insects remarked that only certain snapshot of weekly changes in the plants had any aphid egg deposition. populations of certain pests.

62 – High Tunnels In addition to scouting and sticky species of parasitoid or predator will for beneficial insects. Excellent cards, there are other monitoring be most appropriate and effective for insectary plants include dill, cilantro, practices. Index plants attract specific your situation. These suppliers and others in the Umbelliferae family; pests. For example, to determine if provide basic directions on how to use yarrow; sea holly; and crimson clover. thrips are present, use New Guinea them and often will help with In a 30' x 96' hoop house, we often Impatiens, a plant they favour. Plants troubleshooting as it is in their interest plant 10 to 12 square feet of like these can also function as a trap for you to be successful with your permanent insectary plants throughout crop that will be destroyed in order to beneficial introductions. (See the high tunnel. reduce the specific insects. Exercise “Beneficial Insects” on page 69.) caution when using this approach. “Banker plants” are host plants grown Early in our greenhouse experience, Provide Food and Habitat to rear pest species that are not we grew Impatiens transplants for sale for Beneficials harmful to the cash crop. Banker in part of a tomato greenhouse. This Growing in the soil (as opposed to plants can be grown in the high was a big mistake, as we invited every hydroponically) allows many tunnel. The pseudo-pests raised on the thrips in the county to infest our beneficial insects to complete their banker plants attract and increase the tomatoes. life cycles and hence respond to pest population of beneficial insects that pressures. For example, Amblyseius can control the “real” pests on cash Pest Control Options cucumeris, a predator mite that crops. A classic example is using Sometimes an insect pest population relishes thrips, needs the soil for part barley or other small grains to raise exceeds the level at which beneficial of its life cycle. Additionally, grain-specific aphids. These aphids, in insects can provide adequate or timely undisturbed soil will encourage turn, attract beneficial insects which control. Faced with this situation, I ground and rove beetles, generalist can control populations of other types might turn to a biorational insecticide, insect predators. of “pest” aphids within the tunnel. such as a fatty acid like Safer’s Soap. A soap application can knock down Some beneficials cannot fly. These Cherish Your Spiders localized outbreaks of certain pests beneficials are easily stranded on a Spiders consume twice their body (e.g., aphids and whitefly), allowing plant “island” after they have eaten all weight every day. While spiders are beneficial populations to gain an the pests within their reach. When the indiscriminate eaters, investigators advantage. canopy of plants inside a high tunnel have found that at least 80% of their touches, it provides a concourse for diet consists of pest insects. (See A drawback of this strategy is the wingless beneficials such as predatory “LeSar and Unzicker” article potential harm to beneficial insects mites and midge larvae. This allows referenced on page 74.) Spiders eat populations, for even these soaps have them to walk between plants so they aphids, leafhoppers, whiteflies, and a lethal effect on some beneficials. can access and attack their pest prey. cucumber beetles, as well as many Restrict the use of botanical pesticides If your plants don’t touch, you need a other pests, and their pheromones also such as rotenone and pyrethrum. different beneficial. scare off a lot of insects. Though natural, these pesticides can devastate beneficial insects as well. Feed beneficial insects. One study Habitat is important to spider survival. documented a 600% increase in They need a hiding place during the Beneficial insects can be purchased to beneficial insects where they were day and in the winter, though they help bring particular pests under fed. One nectar substitute is 3 to 6 may overwinter in the soil. Easy-to- control. It is absolutely critical to ounces of powdered sugar dissolved make spider condos consist four or introduce beneficial insects before the in a gallon of water. A pollen five 6" long bamboo sections bundled pest population can no longer be substitute is a half-pound nutritional together. To make a section, cut the controlled by beneficials. Therefore yeast dissolved in water. Spray these bamboo so that it includes a node near regular monitoring is an essential solutions every week to 10 days when one end. It should look like an upside component of any biological control you see pests. When using these down test tube or a pipe with a cork in program. nectar and pollen substitutes, exercise it at the top. Wrap four or five of these caution about foliar diseases. together and place them near problem In my climate and growing pest areas as needed. These can be conditions, I have introduced parasitic Insectary Crops suspended a couple inches off the wasps such as Aphidius colemani to We establish insectary crops for food ground attached to the inner cover control aphids and Encarsia formosa and habitat. These are plants that support structure. to control whitefly. Beneficial insect flower rapidly and are good nectar suppliers can help you determine what sources, providing high-energy food

63 – High Tunnels Glossary

Come-along. A hand operated geared rachetting device to pull heavy objects. Drift punch. A tapered metal pin used to align holes, knock out bolts or other debris from holes. Ground pipe, post, or pin. A pipe buried in the ground and attached to the bow to support the structure. It functions as an anchoring foundation member. Haygrove. A company, based in the United Kingdom, that manufactures field scale tunnels, mobile livestock buildings and specialist horticultural machinery. They manufacture multi-bay high tunnels. PEX. Cross-linked high-density polyethylene used as tubing in radiant heating systems. Pike pole. A pole that has a natural or designed hook on one end that catches the bow and assists in pushing the bow, especially above one's reach. Plumb. To make something perpendicular to the earth's surface using gravity (typically a string and heavy weight). Purlin. Typically a horizontal length of swedged pipe attached at the ridge and points along the bow to add structural integrity and strength. Spline. In high tunnel/greenhouse construction a spline is a short (approx. 12" to 18”) pipe used to join two similar diameter pipes, usually the bow and ground pin/pipe. The spline has a smaller outside diameter (O.D.) than the inside diameter (I.D.) of the two pipes it is joining. These pipes are commonly joined by tek screws or bolts. Swedged pipe. 4" or 5” of one end of a pipe is rolled to a smaller diameter, allowing it to be inserted into the end of another pipe. Truss. A structural member (pipe in high tunnels) connecting the bows and often the ridge purlin. It adds structural strength.

64 – High Tunnels Resources

This list is not intended to be www.harnois.com Mid-Atlantic with a broad line of complete and does not comprise an A leading greenhouse structures and products. Online catalog. endorsement of the companies listed. equipment manufacturer, their There are many other reputable extensive line of greenhouses includes Growell Greenhouses manufacturers and distributors besides gutter connects and a unique vent Mike Tripedino, owner those listed below. ridge system. Their freestanding 40' 791 Coleman Rd. OIvaltech has 10' high roll-up sides Cheshire, CT Greenhouse Structures for maximum ventilation and natural 203/272-8147 Also see “Multi-Bay Structures” light. Greenhouse and solarium builders and distributor of greenhouses equipment Ledgewood Farm Greenhouse Atlas Greenhouse Systems and supplies. Mike is helpful and Frames 9596 US Hwy 82 East, P.O. Box 558 willing to walk you through putting Ed Person, owner Alapaha, GA 31622 up your own house. He will also send 132 Old Mountain Rd. 800/346-9902, 229/532-2905 crews to erect houses and re-cover Moultonborough, NH 03254 Fax 229/532-4600 them. 603/476-8829 [email protected] [email protected] www.atlasgreenhouse.com/cf.html Nexus Corporation www.ledgewoodfarm.com Manufacturer of agricultural, 10983 Leroy Drive Manufactures pipe frame greenhouses educational and hobby greenhouses Northglenn, CO 80233 and high tunnels. Ledgewood frames and a large supplier of greenhouse 800/228-9639, 303/457-9199 are used in all areas of agriculture for equipment for the commercial Fax 303/457-2801 plant protection, livestock housing, greenhouse grower. Freestanding and www.nexuscorp.com and storage. Why not buy from a gutter connected greenhouses as well Serving commercial greenhouse fellow farmer who grows in the as cold frames and shade structures to growers for over 35 years with a structures he sells! small or large size growers around the broad range of greenhouse structures world. Atlas inventories a and excellent customer service. All Rimol Greenhouse Systems, Inc. comprehensive selection of heaters, their structures can be customized for Bob Rimol fans, coverings, ground fabrics, shade the size, covering, heating, cooling, Northpoint Industrial Park cloth, doors, and many other and controls. 40 Londonderry Turnpike specialized items in our own Hooksett, NH 03106 warehouse ready for immediate XS Smith 877/746-6544, 603/629-9004 shipping. Corporate Headquarters www.rimol.com/agricultural.asp 932 Page Rd. A newer manufacturer of Griffin Greenhouse & Nursery Washington, NC 27889 greenhouses; shade structures and Supply 800/631-2226 related systems, serving primarily 1619 Main Street, P.O. Box 36 Also 1602 Lawrence Ave., Suite 103 small and medium-size businesses. Tewksbury, MA 01876 (corporate Ocean, NJ 07712 Many different options available for office) 732/643-0433 heating, cooling. environmental 978/851-4346 Fax 732/643-0699 control, irrigation, and crop support www.griffins.com [email protected] systems. Strong customer support Regional offices: [email protected] includes prompt delivery, outstanding Auburn, NY 315/255-1450 Manufacturer of greenhouse structures directions, and availability of Brookhaven, NY 631/286-8200 and horticultural products since 1946. experienced staff to answer questions. Bridgeton, NJ 856/451-5170 Wide line of greenhouses from small All greenhouses are designed for Cheshire, CT 203/699-0919 ground-to-ground Quonset structures heavy snow and wind loads. Ewing, NJ 609/530-9120 to multi-span gutter-connected Latham, NY 518/786-3500 complexes. Harnois Industries Morgantown, PA 610/286-0046 1044 Principale C.P. 150 Gray, ME 207/657-5442 W. H. Milikowski, Inc. St-Thomas (Joliette) Founded in 1947 by Charles J. 10 Middle River Drive Quebec, Canada, JOK 3LO Griffin. A major greenhouse and Stafford Springs, CT 06076 888/427-6647 nursery supplier in the Northeast and 860/684-1595, 800/243-7170

65 – High Tunnels Fax 860/684-3022 Various thicknesses of CLEAR (and Full-line greenhouse and nursery Greenhouse colored) Superstrong Woven Poly for supplier, including a range of greenhouses, barn curtains, etc. structures made by Star Steel, an Supplies and affiliate. Serves New England and Plastic Disposal Recoltech adjacent region with warehouses in (Plastic film, row cover, plastic 519 Notre-dame St CT, NJ, and Syracuse, NY. disposal, greenhouse supplies, Rémi, Québec, Canada J0L 2L0 irrigation supplies) 450/454-6996, 877/254-6996 CropKing Inc. Fax 450/454-7167 230 Quadral Dr. Plastic Film [email protected] Wadsworth, OH 44281 www.recoltech.com

330/335-1687, Fax 330/335-1689 Plastic mulches, floating row covers, Farm Tek [email protected] drip and other irrigation equipment. 1440 Field of Dreams Way www.cropking.com Primarily a French speaking company. Dyersville, IA 52040 A 23-year-old company specializing 800/327-6835, Fax 800/457-8887 in controlled environment agriculture www.farmtek.com and hydroponics, CropKing is a Commercial greenhouses and Row Cover manufacturer, importer, and supplies, tension fabric buildings, distributor of commercial facility range farm products, etc. American AgriFabrics structures, hydroponic growing 1282 Old Alpharetta Rd. systems, supplies, and equipment, in Green.Tek, Inc. Alpharetta, GA 30005 North America and the Caribbean. 417 East Fulton Street 800/565-5151, 770/663-7600

Edgerton, WI 53534 Retailer and wholesaler of AgroFabric

800/747-6440, Fax 608/884-9459 Reemay, landscape fabric, netting. Multi-Bay Tunnels [email protected] www.green-tek.com Dubois Agrinovation Inc. Haygrove Tunnels Green-Tek is a leading converter and 478, Notre-Dame Ralph Cramer (East Coast Contact) fabricator of plastic coverings for the Saint-Remi, Quebec, Canada J0L 2L0 116 Trail Road North greenhouse and architectural glazing 450/454-3961, 800/667-6279 Elizabethtown, PA 17022 industries. Products include www.DuboisAg.com 866-HAYGROVE polycarbonate multiwall and Row cover, irrigation supplies, plastic [email protected] corrugated sheeting, poly films, and mulch, bird netting, etc. Formerly www.haygrove.com shade cloth. “Plastitech.” Also see www.haygrove.co.uk World leaders in the design and Klerks Plastics Products Ken-Bar, Inc. manufacture of field scale tunnels, 546 L&C Distribution Park Summit Industrial Park mobile livestock buildings and Richburg, S.C. 29729 147 Summit St., Building 3D, Suite 3 specialist horticultural machinery. 888/255-3757, Fax 803/789-4001 Peabody, MA 01960 Haygrove are growers based in www.klerksusa.com/products 800/336-8882, 781/944-0003 Herefordshire in the United Kingdom. Klerks is a global supplier of high Fax: 781/944-1055 quality plastic products for [email protected] horticulture and agriculture. Some of www.ken-bar.com its breakthroughs in greenhouse films A pioneer in developing and are KoolLite 380 and advanced long- providing new and innovative lasting anti-condensation films. products to the grower since 1972. KoolLite 380 selectively filters the Products include SRM-Red reflective light spectrum, giving growers the plastic, floating row covers such as highest quality of PAR light available. Dupont 5131(formerly “Typar 518”) and Dupont Ag-06 (formerly Northern Greenhouse Sales “Remay”), Agritape root zone heaters, Box 42, Neche, ND 58265 and convection tubing. Also makes a 204/327-5540 high tunnel ridgevent distributed Farm www.northerngreenhouse.com Tek.

66 – High Tunnels Peaceful Valley Farm & Garden NJ Department of Agriculture seeds, irrigation equipment, general Supply PO Box 330, Trenton, NJ 08625-0330 supplies. P.O. Box 2209 609/984-2506, Fax 609/341-3212 Grass Valley, CA 95945 [email protected] International Technology Services 888/784-1722 www.nj.gov/agriculture/divisions/md/ P.O. Box 75 [email protected] prog/recycling.html Lafayette, CO 80026 www.groworganic.com Ms. Kritz is the recycling maven who 800/375-1684 Row covers, pest management, tools, initiated NJ’s horticultural film rghome@ intertechserv.com propagation supplies, etc. Distributes recycling programs. www.greenhouseinfo.com Tufbell, a hard-to-find, expensive but Serving conventional and organic extremely durable row cover made of Cumberland County Improvement growers for over 20 years. Beneficial polyvinyl alcohol. Online catalog. Authority insects, pest trapping and monitoring Dennis DeMatte, Recycling supplies, pest identification guides, Polymer Group Inc. Coordinator bumblebees form pollination, 800/631-5594, Fax 919/207-3140 2 North High St. fertilizers and fertilizer injection www.agribon.com Millville, NJ 08332 systems, biological and botanical www.polymergroupinc.com 856/825-3700 pesticides, polypropylene ground PGI is a global leader of engineered [email protected] covers, etc. fabrics, manufacturing and www.ccia-net.com distributing more than 150 products A recycling collection and marketing K.C. Schaefer Supply Co. Inc including Agribon and Agriforce. program for horticultural film and 2655 Springwood Rd. Purchase from a grower supply other materials in southern NJ. York, PA 17402 company. Procedures for preparing plastic film 717/741-5088, Fax 717/741-5089 for recycling downloadable from www.schaefer-hort.com Suntex CP, Inc. website. Out of state materials Wholesales farm supplies. P.O. Box 21633 accepted. Sarasota, FL 34276 (Sales) Nolts Produce Supply 888/786-8391, Fax 941/847-0600 Trex Company 152 N. Hersey Ave. Order fax 888/786-8394 Andrea Dahl Leola, PA 17540 [email protected] 160 Exeter Dr., Winchester, VA 717/656-9764 www.suntexcp.com 22603 Very good, reliable source of The Suntex agricultural line includes 800/289-8739, 540/542-6300, agricultural supplies. Covertan Pro non-woven row covers [email protected] & Agro Poly Embossed Mulch Films. Ms. Dahl can assist entrepreneurs in Silver Creek Supply Covertan Pro is transparent, and air creating collection programs for 5656 S. Susquehanna Trail and water permeable, assuring agricultural plastic films. Clear, clean Port Trevorton, PA 17864 unifiorm heat and moisture exchange. plastic films are preferred. 570/374-8010, Fax 570/374-8071 [email protected] For more background and resources www.silvercreeksupply.net Plastic Disposal on agricultural plastic recycling, visit: Greenhouse, lawn and garden, and environmentalrisk.cornell.edu/AgPlastics nursery supplies, including seeds, Daniel Zook irrigation products, fertilizers, and Zook Plastic Recovery mulch plastics. 183 South Farmersville Rd. Greenhouse Supplies Leola, PA 17540 Wetsel Growers Supply 717/656-4422 Hydro-Gardens, Inc. P.O. Box 791 Call for collection schedule. Mr. Zook P.O. Box 25845 961 North Liberty Street is now paying up to $80 - $100 for Colorado Springs CO 80936 Harrisonburg, VA 22801 clean greenhouse film. Highest prices 800/634-6362 540/434-6753, 800/572-4018 are during his seasonal drives. [email protected] Fax 540/434-4894 www.hydro-gardens.com [email protected] Karen Kritz Since 1968, a specialist in www.wetsel.com Agricultural Economic Development hydroponics. Greenhouse supplies, Wetsel’s commercial grower Division of Marketing & organic fertilizers, pest management department supplies greenhouse Development supplies, beneficial insects, books, frames and skins, environmental

67 – High Tunnels systems, watering and irrigation Netafim USA protective equipment and supplies for systems, and other items. Drip Irrigation Solutions agricultural production, maintenance, 5470 E. Home Ave. etc. Fresno, CA 93727 Irrigation 888/NETAFIM, 559/453-6800 Timberleaf Soil Testing Fax 800-695-4753 39648 Old Spring Rd. Also see “Nolts Produce Supply” www.netafimusa.com Murrieta, CA 92563-5566 under “Greenhouse Supplies.” Full range of drip and micro-irrigation 951/677-7510 products and technical support. Since [email protected] Charles W. Harris Company, Inc. 1965. The Timberleaf soil test was Jim Peeler, owner developed especially for market New address: 72 Tower Hill Rd. Rain-Flo Irrigation gardeners who practice the Brimfield, MA 01010 884 Center Church Rd. biointensive approach. The basic soil 888/928-3731 East Earl, PA 17519 test includes base saturation/CEC, Full line of agricultural irrigation 717/445-6976 estimated nitrogen release, available equipment and supplies. Leading manufacturers of plastic nutrients, pH, and soluble salts. laying and removing machinery, Optional tests exist for organic matter, DripWorks, Inc. water-wheel transplanters and trace minerals, and composts/ 190 Sanhedrin Circle suppliers of plastic mulches, irrigation greenhouse media. The detailed soil Willits, CA 95490 equipment including drip, overhead test report contains the test results and 800/522-3747 pipes, and pumps and floating row explanations, and organic fertilization Design & Tech Support 707/459-6323 covers. recommendations. Fax: 707/459-9645 [email protected] Trickle-eez Company Also for General Agriculture: [email protected] Sales Offices: www.dripworksusa.com 4266 Hollywood Rd. Ben Meadows Company Quality drip irrigation and micro St. Joseph, Michigan 49085 P.O. Box 5277 irrigation supplies for home owners, 800/874-2553, 269/429-8200 Janesville WI 53547-5277 landscapers, farmers and greenhouse Fax 269/429-6669 800/241-6401, Fax 800/628-2068 owners. Drip emitters, micro sprayers, 3550 Chambersburg Rd. www.benmeadows.com emitter tubing, T-Tape® drip tape, Biglerville, PA 17307 An extensive line of soil testing misters, timers, filters, etc. Their on- 800/672-4700, 717/337-3030 supplies includes electrical line store has complete product line Fax 717/337-1785 conductivity meters (starting at $100), with product descriptions. [email protected] penetrometers, shear tester, soil www.trickl-eez.com charts, soil educational kits, soil International Irrigation Systems - A leading dealer in drip irrigation, and testing meters, tensiometers and Irrigro other types of irrigation systems for irrometers, test kits and strips, tile P.O. Box 163, 1755 Factory Outlet Blvd. over 25 years. probes, auger kits, rotary hammer kits, Niagara Falls, NY 14304-0163 sieves, and accessories. 877/477-4476 (IRRIGRO) 905/688-4090 Monitoring and Testing More Scientific: Fax 905/688-4093 Equipment [email protected] Cole-Parmer www.irrigro.com Gempler’s 625 Bunker Court Equipment and supplies for the P.O. Box 44993 Vernnon Hills, IL 60061 watering needs of commercial Madison, WI 53744-4993 800/323-4340, Fax 847/247-2929 growers and home gardeners 800/382-8473 [email protected] worldwide. With over 20 years of [email protected] www.coleparmer.com manufacturing and field experience, www.gemplers.com Specialized equipment for monitoring Irrigro has made significant Gempler’s carries many soil sampling plant nutrition and soil nutrient levels. technological breakthroughs (such as supplies including pH kits, nitrate Extensive list at their website. super-strength seals, pressure testing kits, soil sampling devices compensating flow controllers, and including soil probes and soil Pike Agri-Lab Supplies subsurface conduit). compaction testers, and many other 154 Claybrook Rd. sampling tools. Also suppliers of Jay, ME 04239

68 – High Tunnels 207/897-9267, Fax 207/897-9268 RVI produces and distributes insects Biointensive Agriculture [email protected] and other organisms, supplies and www.pikeagri.com tools for biological control of pests. Ecology Action This family-run business provides test Safe alternatives to microbes “from 5798 Ridgewood Rd kits and monitoring instruments to insects to microbes.” Biological Willits, CA 95490 assist farmers and composters and control programs use predators, 707/459-0150 promote biological agriculture. Pike parasites, pathogens and antagonists www.growbiointensive.org Agri-Lab also develops and and build on active beneficial For the past 31 years, Ecology Action manufactures tools in Maine and can microbes in soil. Sole distributor for has been researching, developing and help farmers set up their own test labs, D-Vac vacuum insect sampling sharing millennial-old techniques for for performing quick, simple tests in equipment. growing more food in a small area, the field. Operating since 1977. Pike using simple tools and seeds, while Agri-Lab sells a combination pH and The Green Spot Ltd. maintaining or increasing the health soil salts (electrical conductivity) 93 Priest Rd. and productivity of the soil. meter for $144. Nottingham, NH 03290-6204 603/942-8925, www.greenmethods.com Seeds and General Farm Beneficial Insects Suppliers of biological control Supplies (Suppliers) organisms and excellent information on individual bio control agents. Johnny’s Selected Seeds IPM Labs. Inc. 955 Benton Ave. P.O. Box 300 Winslow, ME 04901 Locke, NY 13092-0300 Beneficial Insects 877/564-6697, Fax 800/738-6314 315/497-2063 (Organizations) [email protected] [email protected] www.johnnyseeds.com www.ipmlabs.com Pennsylvania Integrated Pest Quality vegetable, herb, and flower IPM Labs supplies beneficial Management Program seeds and tools, equipment, and organisms for the biological control of Cathy Thomas, Coordinator supplies to critical home gardeners pests and provides support to facilitate PA Dept. of Agriculture and small commercial growers. An their successful use. They produce 7 Bureau of Plant Industry independent company since 1973 and species of beneficial organisms and 2301 North Cameron Street employee owned since 2006. All of distribute more than 45 other species. Harrisburg, PA 17110-9408 Johnny's seeds and accessories are 717/772-5204 tested at the company's certified Great Lakes IPM [email protected] organic farm in Albion, ME. 10220 Church Rd., NE paipm.cas.psu.edu/green/greenhouse.html Vestaburg, MI 48891 A highly recommended resource. Seeds 989/268-5693, 989/268-5911, or P.O. Box 520 800/235-0285, Fax 989/268-5311 IPM Program—NYS Agricultural Waterville, ME 04903-0520 [email protected] Experiment Station 207/873-7333 www.greatlakesipm.com P.O. Box 462 www.fedcoseeds.com Insect monitoring systems for the Geneva, NY 14456 A source for cold-hardy selections professional grower. Suppliers of 315/787-2432, 800/635-8356 (seeds, tubers, trees, and bulbs) pheromone lures, insect traps, visual Fax 315/787-2360 adapted to the Northeast climate as traps, insect sweep nets, ground www.nysipm.cornell.edu well as a large selection of certified cloths, bird netting, trapping www.nysaes.cornell.edu/recommends organic cultivars and regional adhesives, soil probes, grain probes The New York State Integrated Pest heirloom varieties. Fedco’s product and thermometers, beneficial insects Management Program develops lines (including organic growers and other insect supplies. sustainable ways to manage pests and supply) and cultural hints encourage helps people to use methods that sustainable growing methods. Three Rincon-Vitova Insectaries Inc. minimize environmental, health, and free catalogs annually. Mail order, fax P.O. Box 95 economic risks. and internet orders only except during Oak View, CA 93022 designated pickup. No phone orders. 800/248-2847 www.rinconvitova.com

69 – High Tunnels Germania Seed Company Bountiful Gardens Tools 5978 North Northwest Hwy. 18001 Shafer Ranch Rd . P.O. Box 31787, Chicago, IL 60631 Willits CA 95490 CSA Works 800/380-4721, 773/621-6631 707/459 6410, Fax 707/459 1925 Michael Docter Fax 800-410-4721 [email protected] Hadley, MA www.germaniaseed.com www.bountifulgardens.org [email protected] Since 1932. Specialist in flowers. Untreated open-pollinated seed of Parts and planting guide for Planet Jr. Distributes annual, perennial and heirloom quality for vegetables, herbs, seeders. vegetable seeds, plants, and plugs. flowers, grains, green manures, compost and carbon crops. Rare and Johnny’s Selected Seeds High Mowing Seeds unusual varieties, medicinal herbs, (See Seed listing) 76 Quarry Rd. super-nutrition varieties. Also Carries hard-to-find market gardener Wolcott, VT 05680 biointensive books/videos for growing tools that are useful for intensive 802/472-6174, Fax 802/472-3201 soil sustainably using mini-farming cultivation in high tunnels. Precision www.highmowingseeds.com techniques such as double-digging, seeders (pinpoint and other models), This small, family-owned, certified intensive spacing, and companion collinear hoes, broadfork, bed organic seed company located in planting. Fine tools, basic organic preparation rake, etc. Northern Vermont ships across the gardening supplies, and non-toxic U.S. to customers who value organic insect controls. Peter B. Johnson seeds, sustainable agriculture, and 7967 Ft. Loudon Rd. good service. Peaceful Valley Farm Supply Mercersburg, PA 17236 (See Row Cover listing) 717/328-4857 Wild Garden Seed [email protected] P.O. Box 1509 U-bar for bio-intensive agriculture Philomath. OR 97370 Miscellaneous Supplies handmade by a family business. 541/929-4068 www.wildgardenseed.com Surplus Center Market Farm Implement This organic seed and vegetable farm P.O. Box 82209 257 Fawn Hollow Rd. in the Pacific Northwest produces Lincoln, NE 68501 Friedens, PA 15541 farm-original varieties of many salad 800/488-3407, Fax 402/474-5198 814/443-1931 greens, vegetables, herbs and a few [email protected] www.marketfarm.com flowers. All seed is open pollinated, www.surpluscenter.com Vegetable crop machinery from untreated, germ and vigor tested in Surplus Center is a warehouse tillage to harvest. Sells Cole Planet Jr. living soil mix, and well cleaned. distributor for many name brand (over $500 per row). manufacturers, such as Parker Hydraulics, Hypro Pumps, Chief Roeters Farm Equipment Hydraulics, and Prince Hydraulics. It 565 120th St. also offers low wattage 12 volt DC Grant, MI 49327 blowers for inflating high tunnel 231/834-7888 plastic using solar power. Many other www.roetersfarmequipment.com products. New and used vegetable equipment, including vintage Planet Jr. seeders.

70 – High Tunnels Further Information and References

These references and resources are Research (SCOAR) and funded by a Acres: A Voice for Eco-Agriculture intended as a starting point for further USDA grant. P.O. Box 91299 reading. This list is by no means Austin, TX 78709 exhaustive or definitive. We National Agricultural Library 518/892-4400 acknowledge that some items may be US Dept of Agriculture [email protected] outdated or difficult to find. 10301 Baltimore Ave. Room 304 www.acresusa.com Beltsville MD 20705-2351 301/504 6559, Fax 301/504-6409 The New Farm: Farmer-To-Farmer Agriculture Information [email protected] Know-How from the Rodale Services www.nal.usda.gov Institute Two resources: AGRICOLA database www.newfarm.org Appropriate Technology Transfer and the Alternative Farming Systems A free electronic newsletter with to Rural Areas (ATTRA) Information Center, searchable database. P.O. Box 3657 (www.nal.usda.gov/afsic) Fayetteville. AR 72702 AGRICOLA, one of the largest 800/346-9140 databases in the world, is a Cold Stress Physiology www.attra.org tremendous resource for academic Free publications, information information. NAL has one of the Levitt, J. Responses of Plants to packets, and other technical assistance world’s largest and most accessible Environmental Stress. Orlando, FL: from the National Sustainable agricultural information collections. Academic Press. 1980. Agriculture Information Service. For farmers, extension personnel, educators, and others involved in Periodicals Environment sustainable agriculture. Created and managed by the National Center for Growing for Market Thorton, PhD, Joe. Environmental Appropriate Technology (NCAT). PO Box 3747 Impacts of Polyvinyl Chloride Relevant publications include: Lawrence, KS 66046. 800/307-8949 Building Materials. A Healthy • Greenhouse IPM: Sustainable [email protected] Building Network Report. 2002. 110 Aphid Control www.growingformarket.com pp. (From the Institute for Local Self- • Greenhouse IPM: Sustainable (Monthly, $33) An informative, Reliance, 202/232-4108, Thrips Control thoughtful magazine mostly written www.healthybuilding.net). • Greenhouse IPM: Sustainable by farmers. Often has useful articles Whitefly Control about growing winter greens. • Root Zone Heating for Greenhouse Supportive of organic, sustainable Fruit Crops agriculture. • Season Extension Techniques for Whitehead, William. Grow Fruit in Market Gardeners HortIdeas Your Greenhouse. London, UK: Faber 750 Black Lick Rd. • Solar Greenhouses Resource List and Faber. 1970. 163 pp. Gravel Switch, KY 40328.

[email protected] Organic Agriculture Information users.mikrotec.com/~gwill/index.html www.organicaginfo.org Gardening (Monthly, $25) Independent Frequently updated website with advertising-free gardening newsletter production information, economic Jeavons, John. How to Grow More that abstracts new information from a data, research results, farmer Vegetables. 6th ed. Berkeley, CA: wide range of sources relevant to anecdotes, certification information, Ten Speed Press, 2002, 240 pp. horticulture. For over two decades. transition strategies, and other subjects related to organic agriculture. Wagenvoort, W.A. and Bierhuizen,

Offered by the Organic Agriculture J.F. Some Aspects of Seed

Consortium (OAC)/Scientific Germination in Vegetables. Scientia

Congress on Organic Agricultural Horticulturae. 6 (1977). 213-219.

71 – High Tunnels General Greenhouse Taylor, T.M. Secrets to a Successful Solstice Publications/Domestic Greenhouse and Business. Melbourne, Technologies Inc. Beckett, Kenneth A. Growing Under FL: Green Earth Publishing Co., Inc. P.O. Box 2043 Glass. New York, New York: Simon 1999. 279 pp. Evergreen, CO 80439 and Schuster. 1981. 96 pp. 303/674-7700, Fax 303/674-7772 [email protected] Bond, John. Handbook for Greenhouse Design A source for finding and purchasing Growing. Bristol, England. National articles, books, and reports on Federation of City Farms. 1991. 20 Aldrich, Robert A. and Bartok, John sunspaces and solar greenhouses. pp. W., Jr. Greenhouse Engineering. Ithaca, NY: Northeast Regional Also see: Edey, Anna. Solviva: How to Grow Agricultural Engineering Service www.healthgoods.com/education/heal $500,000 on One Acre and Peace on (NRAES, Cooperative Extension, PO thy_home_information/Building_Desi Earth. Martha’s Vineyard, MA.: Box 4557, Ithaca, NY 14852-4557, gn_and_Construction/reading_sunspa Trailblazer Press, 1998. 221 pp. 607/255-7654, [email protected], ces_greenhouses.htm www.nraes.org). Revised ed. NRAES- Grotzke, Hienz. Biodynamic 133. 212 pp. $30. Greenhouse Management. High Tunnel & Season Biodynamic Farming and Gardening Bartok, John W., Jr. Energy Extension Publications Association. 1998. 112 pp. $12. Conservation for Commercial (25844 Butler Road, Junction City, Greenhouses. Ithaca, NY: NRAES. Coleman, Eliot. The New Organic OR 97448, 888/516-7797, Revised ed. 2001. NRAES-3. 84 pp. Grower’s Four-Season Harvest. White www.biodynamics.com). $17. River Junction, VT: Chelsea Green Publishing Co. 1992. 212 pp. Mazria, Edward. The Passive Solar Bartok, John W., Jr. Greenhouses for Energy Book. Emmaus, PA: Rodale Homeowners and Gardeners. Ithaca, Coleman, Eliot. The Winter Harvest Press. 1979. 435 pp. NY: NRAES. 2000. NRAES-137. 200 Manual: Farming the Backside of the pp. $30. Calendar. Four Season Farm, 609 McCullagh, James C., ed. The Solar Weir Cove Rd., Harborside, ME Greenhouse Book. Emmaus, PA: Bartok, John W., Jr. Retractable Roof 04642. 1998. 57 pp. Order from Rodale Press, 1978, 328 pp. Greenhouses and Shadehouses. Fedco, Growing for Market, or Factsheet. Available at: directly from Eliot at above address. Salt, Bernard. Gardening Under www.hort.uconn.edu/Ipm/greenhs/barto Plastic: How to Use Fleece, Films, k/htms/retractableroofgreenhouses.htm. Dreer, Henry A. Vegetables Under Cloches and . London, Glass. Henry A. Dreer, 714 Chestnut UK: B.T. Batsford Ltd. 127 pp. Mazria, Edward. The Passive Solar St., Philadelphia, PA. 2nd ed. 1896. Energy Book. Emmaus, PA: Rodale 105pp. Smith, Shane. The Bountiful Solar Press. 1979. 435 pp. Greenhouse; A Guide to Year-Round Gerst, Jean-Jacques. Growing Food Production. Santa Fe, NM: John Vegetable Crops Under Direct Muir Publications Inc. 1982. 221 pp. Greenhouse Plans Covers. Paris, France: Centre Technique Interprofessionnel des Story, David. Plastic and Vegetables: Sunspace & Solar Greenhouse Plan Fruits and Legumes. 1987. 165 pp. A Guide to Organic Growing in Brace Research Institute Polytunnels. Dublin, Ireland: IOFGA Publication Dept., Faculty of Byczynski, Lynn, ed., The Hoophouse (Irish Organic Farmers and Growers Engineering, P.O. Box 900 Handbook: Growing Produce and Association). 1993, 54 pp. MacDonald College of McGill Flowers in Hoophouses and High University Tunnels. Lawrence, KS: Growing for Stinson, Richard F. Greenhouse Crop Ste. Anne de Bellevue, Quebec, H9X Market. 60 pp. $15. 800/307-8949. Production, Student Manual. University 3V9, Canada Park, PA: PSU. 1983. 223 pp. 514/398-7833, Fax 514/398-7767 Jett, Lewis. High Tunnel Tomato [email protected] Production Guide (Publication M170). University of Missouri. Details about building a hoop house, with many photos, plus tomato production

72 – High Tunnels information including color photos of Michigan Reid, Judson insects, disease, and physiological John Biernbaum Cornell Vegetable Program disorders. 28 pp. $10. From MU Ext. Michigan State University Dept of 315/536-5123 Publications, 800/292-0969, Horticulture [email protected] muextension.missouri.edu/explore/ma 517/355-5191 x419 Tomato, cucumbers, peppers and nuals/m170.htm [email protected] cover crops variety trials in high Winter growing in unheated tunnel tunnels. Janick, Jules and Swaim, David. research since 2001. Also 48-week Development of an Innovative CSA at student organic farm Stephen Reiners Production and Marketing System for New interactive online course in Dept. of Horticultural Sciences, NYS Specialty Vegetables. Final Report. 2007: Passive Solar Greenhouses for Ag Experiment Station No date. Purdue University. Protected Cultivation (credit and non- 315/787-2311 www.hort.purdue.edu/newcrop credit enrollment options). Future [email protected] /hfresh/finalreport.pdf courses on compost and organic General vegetable culture, soil transplants. fertility. Lamont, Bill and Orzolek, Mike. High Tunnel Production Manual 2003. Maine Chris Wien Over 150 pp. $26.50 payable to Penn Barbara Murphy Dept. of Horticulture, Cornell State University. Mail payment to Dr. University of Maine Cooperative University Bill Lamont, Dept. of Horticulture, Extension, Oxford County 607/255-4570 206 Tyson Building, Penn State 207/743-6329 [email protected] University, University Park, PA [email protected] Season extension in cut flowers, day 16802. Comparison of cut flower production length considerations in manipulating in field and in high tunnel, including time of bloom. Poisson, Leandre and Gretchen. Solar season extension. Gardening. White River Junction, VT: Ohio Chelsea Green Publishing Co. 1994. Gleason Gray Ron Becker 267 pp. University of Maine Cooperative Ag & IPM, Ohio State University Extension, Penobscot County Extension, Wayne County Wiediger, Alison and Paul. Walking 207/942-7396 330/264-8722 to Spring: Using High Tunnels to [email protected] [email protected] Grow Produce 52 Weeks a Year. Active solar heating in a high tunnel Implementation of Integrated Pest From Au Naturel Farm, 3298 for spring and fall season extension. Management practices in high tunnels. Fairview Church Road, Smiths Grove, Experimental design includes black KY 42171. $15 plus $3.50 S/H or tubing containing circulating water Brad Bergefurd from Growing for Market. mounted on bows, flexible tubing Ohio State University South Centers buried 6" deep, and a buried 5,000 740/289-2071 x136 gallon storage tank. [email protected] High Tunnel Research, http://southcenters.osu.edu/hort/ Education and Websites New Jersey High tunnel strawberries, tomatoes, Rutgers University High Tunnel and moveable tunnel structures – Connecticut Project. See archived reports at: research, extension, on-farm Martin Gent aesop.rutgers.edu/~horteng/HighTunn demonstrations. Dept. of Forestry and Horticulture els/HighTunnels2005.pdf Connecticut Agricultural Experiment Matt Kleinhenz Station New York Dept. of Horticulture and Crop 203/974-8489, Marvin Pritts Science, Ohio Agricultural Research [email protected] Cornell Dept. of Horticulture and Development Center Physiology of high tunnel crops – 607/255-1778 330/263-3810 growth, yield, nutrients, environment [email protected] [email protected] Small fruit in high tunnels – High tunnel design, use in Kansas, Missouri, and Nebraska raspberries, strawberries, etc. conventional and organic systems, www.hightunnels.org cultural practices and product quality. High Tunnel Team of Central Great Plains

73 – High Tunnels Pennsylvania Jordan, William H. Jr. Windowsill Nitrates Center for Plasticulture, Penn State Ecology: Controlling Indoor Plants University With Beneficial Insects. Emmaus, PA: Affleck, Elisabeth A. Nitrate Levels in http://plasticulture.cas.psu.edu Rodale Press. 1977. 229 pp. Greenhouse Grown Salad Mix: A Research, events, experimental Case Study of Three Sisters results, etc. Koppert Biological Sysems. Koppert Bioshelter, (unpublished). Dept. of Side Effects Database: Side Effects of Parks and Recreation, Slippery Rock Pesticides on Beneficial Organisms. University, Slippery Rock, PA. May Insects (Beneficial and www.koppert.nl/e0110.html 1998. 48 pp. Pest) LeSar, Charles D. and Unzicker, John Sideman, Eric PhD. Nitrate Carr, Anna. Rodale’s Color Handbook D. Life History, Habits and Prey Accumulation In Winter-Harvested of Garden Insects. Emmaus, PA: Preferences of Tetragnatha laboriosa. Crops: A Growers’ Guide. Maine Rodale Press. 1979, 241 pp. 1978. Environmental Entomology: 7. Organic Farmer and Gardener. June- August 1999. 40-41 pp. Casey, Christine, ed. Integrated Pest Scopes, Nigel E.A. and Ledieu, Management for Bedding Plants. Michael S. Integrated Control of Ithaca, NY: Cornell University Press. Tomato Pests (Growers Bulletin No. Salinization 1999. 117 pp. $14.50 3). Littlehampton, West Sussex, England: Glasshouse Crops Research Alberta Government Agriculture, Cherim, Michael S. The Green Institute. 1979. 28 pp. Food, and Rural Development. Salt Methods Manual. Nottngham, NH: Tolerance of Plants. The Green Spot Publishing, Ltd. Thomas, Cathy and the Pennsylvania http://www1.agric.gov.ab.ca/$departm 1998. 238 pp. IPM Program. Greenhouse IPM with ent/deptdocs.nsf/all/agdex3303. an Emphasis on Biocontrols. Penn Flint, Mary Louise and Dreistadt, State University. Based on Bug vs. Kotuby-Amacher, Jan, Koenig, Rich Steve H. Natural Enemies Handbook: Bug article series. 108 pp. Over 90 and Kiutchen, Boyd. Salinity And The Illustrated Guide To Biological full-color images. Plant Tolerance. Utah State University Pest Control (Pub. 3386). Oakland Download free PDF file from Extension. AG-SO-03. July 1997 CA: U. of CA, Div. of Agriculture and http://paipm.cas.psu.edu/ghmanual.htm http://extension.usu.edu/files/agpubs/s Natural Resources Communication Or send check or money order for alini.htm. Services. 1998. 154 pp. hard copy ($12 plus $5 S/H per order) to Publications Distribution Center, Gill, Stanton and Sanderson, John. PSU, College of Ag. Sci., 112 The Ball Identification Guide to Ag.Admin. Building, University Park, Greenhouse Pests and Beneficials. PA 16802-2602. Credit card orders, Batavia, IL: Ball Publishing. 1998. 877/345-0691. 244 pp.

Howard, R.J., Garland, J.A., and Seaman, W.L. Diseases and Pests of Vegetable Crops in Canada. Societe d’entomologie du Canada, 393 Winston Avenue, Ottawa, ONT, Canada K2A lY8. (613/725-2519) ISBN 0-9691627-3-1 (soft and hard cover, English and French).

74 – High Tunnels