potential (Ferguson et al., 2012; Orientation of Small Hobby High Tunnels Lamont, 2009; Ortiz et al., 2012). and Potential Effects on Cut Sunflowers and Numerous factors may affect growth of crops in high tunnels, Fresh Herbs including orientation of the struc- ture (Sethi, 2009). General studies 1,4 2,3 on high tunnel orientation indicate Karen L. Panter , Timmothy M. Gergeni , that growers in the northern hemi- Casey P. Seals2,3, and Andrea R. Garfinkel2,3 sphere should orient high tunnels with the long sides running NS to maximize solar radiation (Sethi, ADDITIONAL INDEX WORDS. Allium tuberosum, cut flowers, Helianthus annuus, 2009). Despite this recommenda- hoop houses, Origanum majorana, Origanum vulgare tion, there is evidence to show that SUMMARY. High tunnels are gaining popularity for their use in horticultural crop the benefits of high tunnel orienta- production. However, little is known about the effect of high tunnel orientation on tion and growing location within plant growth and development. In this set of studies, we show tunnel orientation a particular orientation may be does not necessarily affect the production of cut sunflower (Helianthus annuus) and crop-specific. Taber et al. (2009) culinary herbs oregano (Origanum vulgare), marjoram (Origanum majorana), and showed that tunnel orientation and garlic chive (Allium tuberosum). Two high tunnels, one with the long axis oriented planting location within a high tun- north-south (NS) and the other east-west (EW), were used to test the effects of high nel negatively affected bean (Phaseo- tunnel orientation on several crops over a 5-year period: cut sunflower (2012 and lus vulgaris) yield, with decreased 2016); marjoram, oregano, and garlic chive (2013 and 2014); and garlic chive productivity of bean plants grown in (2015). The tunnels are 12 · 16 ft, smaller than those used in commercial pro- duction. The size would be appropriate for hobby and seasonal production of north (in an EW-oriented tunnel) horticultural crops for local markets. Cut sunflower stems were similar lengths both and west (in a NS-oriented tunnel) years in both high tunnels. Sunflower times to harvest were different between growing locations. cultivars but not between high tunnels. Oregano fresh weight yields were highest in The sunflower will flower from the NS tunnel in 2013 but similar between tunnels in 2014. Marjoram fresh weights 75 to 150 d after sowing (Fern andez- were highest in 2013 in the EW tunnel but highest in 2014 in the NS tunnel. Garlic Martinez et al., 2009), with temper- chive fresh weights were similar between tunnels all 3 years. We show that differ- ature and photoperiod significantly ences are more a function of innate cultivar characteristics than which way small affecting time from sowing to matu- high tunnels are oriented. rity (Fern andez-Martinez et al., 2009; Schuster, 1985). Cool temperatures igh tunnels are important into greenhouses, high tunnels, and delay flowering, whereas warm tempera- alternatives to greenhouse other season-extending environments tures accelerate maturation (Fern andez- Hor field production of high- (Cavins et al., 2000; Ortiz et al., 2012; Martinez et al., 2009). value crops such as cut flowers and Wien, 2009a). Not only do high tun- Due to their hardiness, garlic herbs (Carey et al., 2009; Wells and nels allow for a local extended growing chive is described as being low main- Loy, 1993; Wien, 2009b). Many cut season, but they also play an important tenance (Folia, 2015). Chive plants flowers and herbs produced in the role in protecting cut flower crops do best in full sun or part shade, and United States are grown in open field from extreme environmental condi- well-drained but moist soil (Gar- settings where year-round produc- tions, including freezing tempera- dener’s Network, 2016). Recom- tion is possible (Bonarriva, 2003); tures, rain, wind, hail, and in some mended growing temperature is 58 however, the interest in locally pro- cases, disease (Lamont, 2009; Wien, F (Nau, 1999). duced horticultural goods has driven 2009a). The increased interest in do- Oregano and marjoram require the regional production of these crops mestic production of cut flowers and similar growing temperatures of 55 herbs in high tunnels and the advan- F. Both are frost-sensitive and are tages of high tunnel production create typically grown as annuals in colder Received for publication 9 Jan. 2019. Accepted for the need for region- and crop-specific climates, unless under controlled en- publication 23 Apr. 2019. research to maximize local production vironments (Nau, 1999). Published online 6 June 2019. The authors appreciate funding support from the Wyoming Department of Agriculture Specialty Crops Grant Program and from the University of Wyoming Agricultural Experiment Station. Units 1Plant Sciences – Department 3354, University of Wyoming, 1000 East University Avenue, Laramie, To convert U.S. to SI, To convert SI to U.S., WY 82071 multiply by U.S. unit SI unit multiply by 2Department of Plant Sciences, University of Wyom- 10.7639 fc lx 0.0929 ing 0.3048 ft m 3.2808 2 2 3Former graduate student. 0.0929 ft m 10.7639
4 2.54 inch(es) cm 0.3937 Corresponding author. E-mail: [email protected]. 1.1209 lb/acre kgÁha–1 0.8922 This is an open access article distributed under the CC 0.0254 mil(s) mm 39.3701 BY-NC-ND license (https://creativecommons.org/ 1 mmho/cm dSÁm–1 1 licenses/by-nc-nd/4.0/). 28.3495 oz g 0.0353 https://doi.org/10.21273/HORTTECH04273-19 ( F – 32) O 1.8 F C( C · 1.8) + 32
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Although a number of studies single-stem characteristics. Single- sunflowers were watered by hand daily. have assessed the potential for pro- stem sunflowers do not branch. One Plants were grown under natural light ducing cut sunflowers and herbs in seed equals one plant that produces and daylength conditions experienced high tunnels (Cavins et al., 2000; one solitary flowering stem (Harris in the hobby high tunnels. Lamont, 2009; Lopez and Ortiz, Seeds, Rochester, NY). The cultivars 2012; Ortiz et al., 2012; Wien, were Dafna and ProCut Bicolor (Har- Herbs 2006), none report on the effect of ris Seeds) (Fig. 1A and B). Three species of fresh culinary high tunnel orientation or growing SUNFLOWER 2012. The two sun- herbs were chosen for study in 2013 location on plant growth. Thus, we flower cultivars were arranged in a ran- and 2014: oregano, marjoram, and set up a series of trials with the domized complete block design with garlic chive (Fig. 1C). The latter was objective of determining differences four replications of four plants each used in 2015. Each of the species in in growth of cut sunflowers and fresh per cultivar arranged in a two-by-two all 3 years was grown as 16 (2013 herbs between high tunnel orienta- square with plants on 6-inch centers. and 2014) and 24 (2015) single- tions. The tunnels are small hobby Blocks were arranged on either side of plant replicates. Each group of one size; therefore, these studies are ap- the central aisle in each high tunnel, species was grown together in one propriate for part-time growers in- four blocks on either side, eight plot; plots were randomly placed terested in seasonal production of blocks total per tunnel. An edge row one on each side of the central aisle horticultural crops for local markets. was planted around the perimeter of in each tunnel (Fig. 1C). Plots were This work represents a combination all sunflower plots to mitigate edge completely surrounded by edge rows of three different graduate students’ effects. of a combination of lavender (Lav- effort over 4 years; some differences in SUNFLOWER 2016. The same andula angustifolia) and rosemary methodology occurred as a result. two cultivars were arranged in a com- pletely random design with 20 single- Materials and methods plant replicates per cultivar on 6-inch Site background centers. Twenty plants were random- Experiments were conducted at ized on each side of the central aisle in the University of Wyoming Laramie each high tunnel, 40 plants total per Research and Extension Center green- tunnel. An edge row was planted house complex. The facility is located in around the perimeter of all plots to Laramie, WY (lat. 41 199120N, long. mitigate edge effects. Different stu- 105 339310W, elevation of 7200 ft) dents pursued these studies in 2012 in U.S. Department of Agriculture cold and 2016; thus the differences in hardiness zone 4b (Fig. 1C). methodology between the 2 years. PROPAGATION. Seeds were sown High tunnels on 2 May 2012 and 26 May 2016 in The high tunnels used in this 128-cell plug trays in a professional study were two 12 · 16-ft arch- germination medium (Fafard Super roof–style tunnels (Solar Star Green- Fine Germinating Mix; Conrad Fafard, houses; Growers Supply, Dyersville, Agawam, MA) and maintained in a IA) covered in a double layer of greenhouse 70/65 Fday/nightona 6-mil uninflated polyethylene plastic mist bench. Misting was controlled with double-walled polycarbonate end with an automated clock system walls. Both tunnels had manual roll-up (Schaefer Solar 3B; Pinnacle Climate sides, up to 3 ft, to provide ventila- Technologies, Sauk Rapids, MN). tion. Sides were rolled up when tem- The mist system was set to trigger peratures exceeded 40 F and down on for 20 s for every 20 solar units when temperatures dipped below collected, where one solar unit is 40 F. The two tunnels were oriented equal to 0.02 molÁm–2 light. Seeds in different directions, one with the from different cultivars, Sunrich Gold long axis running NS and the other (2012) and Sunbright Supreme (2016) EW (Fig. 2). In Apr. 2012, 2013, (Harris Seeds), were sown on the same and 2015, before planting, soil in the schedule and were used as edge rows. tunnels was amended with 2 inches of After 15 d (17 May 2012 and 10 peatmoss and compost, spaded into June 2016), seedlings were trans- a depth of 6 inches. Soil in the tunnels planted on 6-inch centers directly is described as sandy loam. into the ground in the high tunnels and immediately irrigated. Thirteen Fig. 1. Photos of plants used in high Sunflower d following transplant, each plant was tunnel orientation studies. Fresh-cut sunflower cultivars grown were Dafna Two cultivars of fresh-cut sun- top-dressed with 2.5 g (1076.4 (A) and ProCut Bicolor (B) in 2012 Á –1 flower were grown in 2012 and 2016. kg ha ) 15N–4.4P–9.9K controlled- and 2016. Fresh herbs grown are Cultivar selections were based on release fertilizer (Osmocote Plus 15– shown in (C), with the photo taken of flower color (brown and gold, the 9–12; ICL Specialty Fertilizers, crops in the high tunnel oriented University of Wyoming’s colors) and Dublin, OH). Throughout production, north-south in 2013.
462 • August 2019 29(4) (Rosmarinus officinalis)plants.Again, differences in methodology reflect dif- ferent students handling the work. PROPAGATION. All plants were grown from seeds (Harris Seeds). Sowings occurred 4 Apr. 2013, 15 Apr. 2014, and 8 Mar. 2015. Seeds were sown in 128-cell plug trays in a professional germination medium (Fafard Super Fine Germinating Mix). Plug trays were placed on a mist bench using a solar mist con- troller (Schaefer Solar 3B) set to come on for 20 s every 20 solar counts. Following germination, seedlings were transplanted directly into the ground in the high tunnels on 12-inch cen- ters: 30 May 2013, 24 May 2014, and 22 May 2015. Ten days following transplant, each plant was top-dressed with 2.5 g (538.2 kgÁha–1)15N– 4.4P–9.9K controlled-release fer- tilizer (Osmocote Plus 15–9–12). Throughout production, herbs were wateredbyhandoncedaily.Plants were grown under natural light and daylength conditions.
Light and temperature measurements Environmental monitors (HOBO Pendant Temperature/Light Data Logger 64K, UA-002-64HOBO; Fig. 2. Diagram of two high tunnels oriented perpendicular to one another. Each Onset Computer Corp., Bourne, MA) is 12 · 16 ft. One is oriented with the long axis north-south and the other with the long axis east-west. The high tunnels are located at the University of Wyoming were positioned 12 inches above the 9 0 ground in the center of each block of Laramie Research and Extension Center in Laramie, WY (lat. 41 19 12 N, long. 105 339310W, elevation 7200 ft). Plants were grown on either side of the central plants to record air temperature and aisle in each high tunnel. Air temperatures were monitored in the center of the light levels, two per high tunnel, growing area of each tunnel at 12 inches, and soil temperatures were monitored four sensors total in 2012 through 4 inches deep in the center of the long side of each high tunnel; 1 ft = 0.3048 m, 2015. 1 inch = 2.54 cm. Soil temperatures were moni- tored using data loggers (HOBO Pendant Temperature Data Logger 64K, UA-001-64; Onset Computer in the NS tunnel and 7.7 and 1.5 open (Dole and Wilkins, 1999), as per Corp.). Each was buried 4 inches dSÁm–1 in the EW tunnel. In 2014, industry standard. Harvest occurred deep in the soil in the center of the the analysis results were pH 7.6 and approximately every other day. Stems long axis of each tunnel, 4 inches EC 2.6 in the NS tunnel and 7.4 and were cut at the soil level and stem from the outside wall. Thus, there 3.6 in the EW tunnel. In 2015, pH lengths were immediately measured were two data loggers per high tun- levels in the NS tunnel were 7.6 with and recorded. The length of the stem nel, four total (Fig. 2). All data log- EC at 1.2; EW pH was 7.7 with EC was measured from the soil level gers were programmed to collect data at 1.3. where the cut was made to the base every 4 h starting at midnight. Organic matter (OM) levels were of the flower head receptacle. Data below 5% in both tunnels. In 2013, were also collected on time to harvest Soil analyses the NS tunnel OM was 3.5%, and the from sowing (days). Soil analyses in each tunnel were EW tunnel was 3.1%. In 2014, the HERBS. In 2013 and 2014, oreg- conducted in spring 2013, 2014, and figures were 4.5% in the NS tunnel ano and marjoram were harvested 2015 (Colorado Analytical Laborato- and 4.9% in the EW tunnel. In 2015, periodically during the growing sea- ries, Brighton, CO). Results indicated levels were NS tunnel 3.5% and EW son, just before flower initiation, at minor differences in characteristics tunnel 2.9%. their peak culinary flavor (Morgan, between the two tunnels. The soil 2005), as per industry standard. texture was sandy loam. In 2013, Harvesting and data collection These were harvested by hand leaving pH and electrical conductivity (EC) SUNFLOWER. Individual flowers two to three nodes on each stem for were 7.9 and 1.3 dSÁm–1, respectively, were harvested when ray flowers were regrowth. Garlic chive was harvested
• August 2019 29(4) 463 PRELIMINARY AND REGIONAL REPORTS when the aboveground biomass was harvested the same days in both high 2014. Garlic chive and oregano at least 6 inches tall, cut to 2 inches tunnels (data not shown). In 2015, all per plant yields between the two high aboveground. Harvested materials garlic chives were harvested at once at tunnels were not different (Table 2). were immediately weighed for fresh the end of the growing season, so no Garlic chive produced 37 g per plant weight. All fresh weights were mea- differences in time to harvest oc- in the NS tunnel and 40 g in the EW sured using a portable scale (PC curred that year either (data not tunnel. Oregano averaged 106 g per 4400; Mettler-Toledo International, shown). plant in both high tunnels in 2014; Greifensee, Switzerland). In 2015, however, marjoram yields were higher garlic chive was harvested once at Herbs: Fresh weights in the NS tunnel (145 g) than in the the end of the growing season for 2013. There were no differences EW tunnel (110 g) (Table 2). total fresh weight, 10 Sept., and in fresh weight yields per plant be- 2015. Marjoram and oregano weighed using a portable scale (model tween the two high tunnel orienta- were not grown in the tunnels in SLB50; Carolina Biological Supply tions with garlic chive. An average of 2015. Garlic chive yields per plant Co., Burlington, NC). 13 g of garlic chive per plant was were similar between the two high harvested from the NS tunnel and tunnels. The NS tunnel averaged 25 g Statistical analysis 16 g from the EW tunnel (Table 2). per plant and the EW high tunnel Data were analyzed and statisti- Marjoram and oregano per plant fresh averaged 22 g on per plant bases cal computations were facilitated us- weights differed between the two (Table 2). ing analysis of variance procedure in high tunnels (Table 2). Marjoram SAS (version 9.3 or 9.4; SAS Insti- per plant fresh weight in the EW Environment tute; Cary, NC). Means separations tunnel was 115 g, significantly higher Average high tunnel air temper- were conducted using Fisher’s least than in the NS tunnel, 85 g (Table 2). atures in 2013, 2014, and 2015 were significant difference at a = 0.05. Oregano showed the opposite, with not different (Table 3). Example tem- higher per plant fresh weight in the peratures during the 2012 growing Results NS tunnel at 117 g than the EW season ranged from a low on 20 May Sunflower: Time to harvest tunnel, 89 g (Table 2). of 33.6 F in both tunnels to highs on 2012. Time to harvest did not differ between NS and EW high tun- nel orientations (Table 1). The only Table 1. Results of analysis of variance and means separation in fresh-cut differences observed in time to har- sunflower time to harvest from sowing and stem lengths when grown in two high vest were between cultivars. Time to tunnels in 2012 and 2016. One high tunnel was oriented with the long axis harvest between the two high tunnel oriented north-south (NS), and the other was oriented east-west (EW). orientations, NS vs. EW, for ‘ProCut High Mean time to Mean stem Bicolor’ averaged 77 and 79 d, re- Yr Cultivar tunnel harvest (d) length (cm)z spectively, which was significantly 2012 Dafna NS 95 ay 123 a fewer than ‘Dafna’ at 95 and 94 d, EW 94 a 110 a respectively (Table 1). ProCut Bicolor NS 77 b 103 a 2016. Time to harvest again EW 79 b 109 a differed between the cultivars Dafna 2016 Dafna NS 80 a 82 a and ProCut Bicolor but there were no EW 80 a 84 a differences between the two high ProCut Bicolor NS 71 b 81 a tunnel orientations. ‘Dafna’ averaged EW 76 b 72 a 80 d in both high tunnels, whereas z1 cm = 0.3937 inch. ‘ProCut Bicolor’ averaged 71 d in the yDifferent letters within a year, cultivar, and column indicate statistical differences using Fisher’s least significant NS tunnel and 76 d in the EW tunnel difference means separation at a = 0.05. (Table 1).
Sunflower: Stem lengths Table 2. Results of analysis of variance and means separation of fresh weight of 2012. Neither ‘Dafna’ nor ‘Pro- culinary herbs garlic chive, marjoram, and oregano, grown in two high tunnels in Cut Bicolor’ differed in stem length 2013, 2014, and 2015. One high tunnel was oriented with the long axis oriented between cultivars or the two high north-south (NS), and the other was oriented east-west (EW). tunnel orientations (Table 1). Mean fresh wt (g/plant)z 2016. There were no differences Yr High tunnel Garlic chive Marjoram Oregano in stem lengths between cultivars or 2013 NS 13 ay 85 b 117 a high tunnels (Table 1). EW 16 a 115 a 89 b 2014 NS 37 a 145 a 106 a Herbs: Time to harvest EW 40 a 110 b 106 a 2013, 2014, and 2015. No 2015 NS 22 a Not grown Not grown differences occurred in time to har- EW 25 a Not grown Not grown vest from sowing between the two z1 g = 0.0353 oz. high tunnels with any crop in either yDifferent letters within a year, herb, and column indicate statistical differences using Fisher’s least significant 2013 or 2014, because each crop was difference means separation at a = 0.05.
464 • August 2019 29(4) 10 July of 106.8 F in the EW tunnel Table 3. Mean high tunnel air (2013, 2014, 2015) and soil temperatures (2012, and 105.8 F in the NS tunnel. Aver- 2013, 2014, and 2015). Two high tunnels were used, one with the long axis age soil temperatures in the east and oriented north-south and the other east-west. Crops grown were fresh-cut south planting locations were statisti- sunflowers or fresh culinary herbs. Locations within high tunnels were as cally higher than those in the west and follows: north and south sections in the east-west tunnel, and east and west sections in the north-south tunnel. Temperatures were recorded every 4 h. north locations in 2012, 2013, and 2015; in 2014, east average soil tem- Location within perature was higher than the other Yr high tunnel Air temp ( C)z Soil temp ( C) three edges (Table 3). Soil tempera- 2012 North NAy 14.4 bx tures within the hobby high tunnels South NA 15.7 a were consistently lower than air tem- East NA 15.7 a peratures (Table 3). West NA 14.6 b Light levels differed between high 2013 North 19.2 a 15.4 b tunnels depending on the time of day, South 19.5 a 17.0 a as shown in data from 2012, a repre- East 20.7 a 16.8 a sentative year (Fig. 3). Lower average West 20.0 a 16.6 b light levels were recorded in the NS 2014 North 18.8 a 15.6 a tunnel than the EW tunnel, particularly South 18.6 a 15.8 a at 0800 and 1200 HR (Fig. 3). East 19.6 a 16.6 a Discussion West 18.7 a 15.6 a 2015 North 25.7 a 18.4 b Sunflower: Time to harvest South 26.1 a 20.0 a The similarities between high tun- East 26.4 a 20.3 a nel orientations with regard to time to West 25.6 a 18.3 b harvest were expected because all were z(1.8 · C) + 32 = F. grown under the same photoperiod. yNot applicable; air temperatures were not recorded in 2012. Photoperiod has been shown to be the xDifferent letters within a year, location, and column indicate statistical differences using Fisher’s least significant majorfactorindeterminingflowerini- difference means separation at a =0.05. tiation and maturation of cut sunflowers (Blacqui ere et al., 2002; Gimelli et al., 2003; Hayata and Imaizumi, 2000; Pallez et al., 2002; Yanez~ et al., 2004, 2005). Variation in time to harvest between the two cultivars tested in this study are in accordance with research that suggests that cut sunflowers are sensitive to photoperiod and that this response is cultivar-specific (Wien, 2012a, 2012b). Wien (2012a, 2012b) showed that ‘ProCut Bicolor’ flow- ered faster under summer, long-day conditions, whereas ‘Dafna’ is slower to bloom during long-day conditions. Fourteen hours has been shown to be the critical daylength to elicit a long- day sunflower response (Blacqui ere et al., 2002); daylength exceeded 14 h throughout both years of study.
Sunflower: Stem lengths Because stem lengths were simi- lar between the two high tunnels, lower light intensities in the NS high Fig. 3. Plot of light intensity by high tunnel orientation and time of day. Data are from two high tunnels oriented perpendicular to one another, one with the long tunnel were apparently not different axis north-south [NS (red)] and the other east-west [EW (blue)]. Data were enough to cause stem lengths to recorded every 4 h starting at midnight 17 May 2012 through 7 Oct. 2012. Each is differ. In our other studies conducted 12 · 16 ft. The high tunnels are located at the University of Wyoming Laramie on sunflower responses to light (Gar- Research and Extension Center in Laramie, WY (lat. 41 199120N, long. finkel and Panter, 2014), we found 105 339310W, elevation 7200 ft); 1 ft = 0.3048 m, 1 lx = 0.0929 fc. light intensity contributed to differ- ences in stem length of cut sunflowers biologically, because stem lengths and Burke, 1998). Our soil tempera- when grown in a greenhouse. Soil were the same between the two tun- tures were lower than recommended, temperature differences in our studies nels. Optimum soil temperatures for but this did not contribute to parame- were statistically different but not sunflowers are 68 F (McMichael ters measured.
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Herbs fresh weights were intermediate in Dole, J.M. and H.F. Wilkins. 1999. Floriculture – Principles and species. 2013, 2014, AND 2015. Differ- 2015, between those from the two ences in fresh weights among the previous years. It seems air tempera- Prentice Hall, Upper Saddle River, NJ. three species did not show any partic- tures are not a contributing factor in Ferguson, C.G., P.G. Vuppalapati, M.J. ular patterns among the 3 years. Fresh herb yields or sunflower time to har- Stone, and E. Gray. 2012. Evaluation of weights of the three species varied by vest or stem lengths; however, soil cultivars of sunflowers (Helianthus annuus year and high tunnel with no easily temperatures were consistently lower L.) and selected environments for pro- discernable cause. Reasons for higher on the north side of the EW tunnel duction of cut flowers. J. Ky. Acad. Sci. fresh weights in general in 2014 prob- and the west side of the NS tunnel. 73:90–95. ably include the human component of Fern andez-Martinez, J.M., B. Perez- simply being more experienced growers. Conclusions Vich, and L. Velasco. 2009. Sunflower, p. It seems differences between the tunnels Our data suggest that in small 155–232. In: J. Vollman and I. Rajcan in soil temperatures, light levels, and tunnels with these dimensions in this (eds.). Oil crops, Vol. 4. Springer Sci. soil properties had little effect overall. location, orientation was not a primary Business Media, New York, NY. production consideration. In this se- Soil temperatures were slightly lower in Folia, 2015. Garlic chive Allium tuberosum. 2014, but fresh weights were slightly ries of experiments, we found that Plant database/garlic chive plant care. 8 Jan. higher that year. Light levels between stem lengths of two cultivars of sun- 2019.
466 • August 2019 29(4) Ortiz, M.A., K. Hyrczyk, and R.G. Lopez. Sethi, V.P. 2009. On the selection of Wien, C.H. 2009b. Floral crop pro- 2012. Comparison of high tunnel and shape and orientation of a greenhouse: duction in high tunnels. HortTechnology field production of specialty cut flowers in Thermal modeling and experimental val- 19:56–60. the Midwest. HortScience 47:1265– idation. Sol. Energy 83:21–38. 1269. Wien, C.H. 2012a. Cut flower cultural Taber, H.G., B.J. Havlovic, and N.P. practice studies and variety trials. Dept. Pallez, L.C., J.M. Dole, and B.E. Howell. 2009. High tunnel pole bean Hort., Cornell Univ., Ithaca, NY. Whipker. 2002. Production and post- evaluation. Iowa State Res. Farm Prog. production studies with potted sun- Rpt. 468. Wien, C.H. 2012b. Sunflower seedling flowers. HortTechnology 12:206–210. daylength response. Dept. Hort., Cornell Wells, O.S. and J.B. Loy. 1993. Row- Univ., Ithaca, NY. Savio, Y. and C. Robinson. 1998. Oreg- covers and high tunnels enhance crop ~ ano, winter marjoram, wild marjoram, pot production in the northeastern United Yanez, P., H. Ohno, and K. Ohkawa. marjoram. In: Specialty and minor crops States. HortTechnology 3:92–95. 2004. Effect of photoperiod on flowering handbook. 8 Jan. 2019.
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