ALABAMA A&M AND AUBURN UNIVERSITIES Greenhouse Production ANR-1106 of Zonal Geranium

n spring and summer, potted Greenhouse Sanitation red geraniums on the front I Years ago, growers retained steps or plants around the mail- plants selected from the seasonal box are a common sight crops to use as stock plants for throughout America. Geraniums the next season. Cuttings were rank number one in terms of taken in winter, rooted, and units sold among flowering pot- maintained under minimum con- ted plants and number three in ditions until early spring for forc- terms of wholesale value. The ing. Several events caused a exact origin of geraniums drastic change in this procedure. (Pelargonium x hortorum) is For one thing, the economics unknown, but they probably of greenhouse space utilization resulted from intercross- combined with the develop- ing between several ment of the “fast-cropping” species native to South method made the old proce- Africa, including P. dures impractical. Major crop zonale, P. inquinans, P. losses from serious systemic scandens, and P. fruteto- diseases such as bacterial blight rum. (Xanthomonus perargonii) and The traditional geranium has Verticillium wilt have also red flowers and green foliage changed cultural practices. and is grown in 4- or 6-inch Because there are no chemical pots. These plants, marketed protectants or cures for these mostly from early April into diseases, the crop must be de- June, make up the bulk of the stroyed once infected. potted-plant market. The flower Today, vegetative material color mix traditionally preferred comes almost exclusively from by customers is 45 percent red, In addition to choosing specialized propagators who use 30 percent salmon, 15 percent which flower colors and contain- culture-indexing and other labo- pink, and 10 percent white. er sizes to market, growers have ratory procedures to eliminate However, customers often want a number of other procedures to systemic organisms such as vas- different container sizes, differ- follow and considerations to cular wilt, bacteria, viruses, and ent flower and foliage colors, keep in mind, including the fol- fungi. Purchasing culture-in- and cultivars that perform in ei- lowing: dexed, clean materials is essen- ther sun or partial shade. They • Keeping the greenhouse sani- tial for successful zonal gerani- also want cultivars suited to tized to avoid disease um production. However, large open gardens, planterARCHIVE• Selecting cultivars because the culture-indexing boxes, window sills, or hanging • Making propagation choices process does not alter resistance baskets. The most popular con- or susceptibility to pathogens, tainer sizes are 3-inch pots, 4- to • Managing stock plants plants can still become infected 41⁄2-inch pots, and 6- to 61⁄2-inch • Using the “fast-cropping” if exposed to diseases during pots. A few zonal geranium cul- method production. The success or fail- tivars that have recently become ure of a production program for available perform well in hang- geraniums therefore depends on ing baskets. employees’ strict adherence to

Visit our Web site at: www.aces.edu and awareness of sanitation! Use Effective sanitation for gera- tings in-house can order unroot- the following rules to keep your niums requires that management ed cuttings for less than what greenhouse sanitized: commit to establishing a certain rooted cuttings cost. • Steam or chemically treat all state of mind or awareness pots, flats, media, etc. that may among employees. This involves Stock Plant Production come in contact with plants. instructing everyone to treat Geranium stock plants are • Ensure that growing medium areas in which geraniums are handled as “clean areas.” Train generally a long-term crop, so is pathogen free. Store media in care should be taken in media disinfected containers or bins. employees from the first day to recognize plant problems, where selection and cultural practice. • Be sure the greenhouse is these problems orginate, how Rooted cuttings for stock plants clean and free of weeds, pests, they spread, and what employee are generally potted into con- and plant debris before planting. behaviors are appropriate within tainers from 6-inch pots to • Use raised benches with sur- clean areas to prevent problems bushel-basket sizes containing a faces that are easy to sanitize. from spreading. Monitor these well-drained, well-aerated, peat- • Disinfect benches, walkways, areas closely to determine the lite medium that does not com- sidewalls, etc. between crops. effectiveness of training. pact and that decomposes slow- • Disinfect irrigation systems, ly. Growers may choose to purchase a commercially pre- such as drip emitters and water Cultivar Selection breakers, between crops. pared medium or mix their own. Cultivar selection for zonal For a mix-your-own, pulverized • Isolate geranium production geraniums is often very market dolomitic limestone (to a pH of steps from other crops. driven. However, for greenhouse 5.8 to 6.5), superphosphate, and • Do not put anything that falls production, consider flower ear- micronutrients in the fritted form on the floor back on the bench. liness, flower and plant unifor- are added at the time of mixing. • Hang hose ends and water mity within a cultivar or series, Watering is usually done breakers—do not let them touch reasonable bench spacing for the using an automatic system, often the floor. market circumstances, minimal microtube watering. Stock plants • Enter the stock plant area only growth retardant use, and a are typically given full sun, except with clean clothes and hands. broad range of flower colors. A during the summer to reduce heat • Wear disposable gloves when list of zonal geranium cultivars in the greenhouse. Stock plants handling stock plants or cuttings. suitable for greenhouse produc- are frequently fertilized using a • Never dip cuttings in solutions tion in the Southeast is included fertilizer tank mix rather than or powders. at the end of this publication. commercial fertilizer so that nutri- • Avoid moving or touching ent levels can be adjusted based media or pots unnecessarily. Crop-Starting Options on monthly soil tests. Start fertiliz- ing at constant liquid feed of 250 • Avoid practices that might Two propagation options are parts per million (ppm) nitrogen splash or move media from the widely used by geranium grow- and potassium. floor to the bench tops or pots. ers. The first option is to pur- Media testing and tissue • Do not put your feet on the chase “clean” cuttings of named analysis are important compo- bench! cultivars for growing stock plants from which cuttings are taken nents in maintaining adequate • Limit and supervise casual visi- fertility for geranium stock tors. for production. The second op- tion is to purchase rooted cut- plants. Test every 2 to 4 weeks • Train employees to recognize tings of named cultivars from during production. Send samples and properly dispose of suspect specialized propagators. The de- from each planting to the Soil plants. cision to grow stock plants and Testing Laboratory, Auburn • Remove all weeds withinARCHIVE the carry out propagation in-house University, Alabama, or to a greenhouse and within 30 feet versus ordering rooted cuttings commercial laboratory. Table 1 outside the greenhouse. is largely an economic one and lists specific recommendations To sanitize equipment, soak depends on the size of the oper- for tissue analysis nutrient levels. it in a 10 percent hospital disin- ation, the space and facilities If one or more nutrients fall out- fectant solution for 60 minutes available, and the skill of the or a 10 percent household growing team. Some suppliers bleach solution for 30 minutes. have recently provided a third option. Growers who have the facilities and want to root cut-

2 Table 1. Zonal Geranium Foliar Analysis Nutrient Level Ranges Propagation Nutrient Percentage Nutrient ppm Cuttings Nitrogen 3.3 to 4.8 Boron 30 to 100 Phosphorus 0.4 to 0.7 Copper 7 to 16 Harvest cuttings early in the Potassium 2.5 to 4.5 Iron 100 to 300 morning, preferably by snapping Calcium 1.0 to 2.0 Manganese 40 to 150 them off manually. It is impor- Magnesium 0.2 to 0.7 Zinc 10 to 50 tant to break the cuttings evenly, with no jagged edges. If you use side of these ranges, take correc- Multiplication Stock a knife, make sure it is sharp, tive steps promptly so that the Production and sterilize it with disinfectant plant growth rate is not adverse- after cutting each stock plant. This method requires smaller ly affected. Make terminal cuttings about 2 containers, usually 6-inch pots, to 3 inches long (larger is not The objective of a geranium and a shorter production time. better) with two maturing leaves. stock plant program is to gener- Pot rooted cuttings in November Remove any basal leaves and ate all the cuttings possible at a or December, and remove, root, petioles that may end up below time when they are needed for and pot cuttings as they become the soil line. In cases where cut- finished production. The two available. Continue to take cut- ting material may be limited, sin- methods of stock plant manage- tings from all plants, and use gle-eye cuttings can be used. A ment that are commonly em- early cuttings as additional stock stem may be divided into several ployed are conventional stock plants. By early spring, you can single-eye cuttings composed of production and multiplication obtain a 1 to 40 (original cuttings an internode and node with at- stock production. to final cuttings) increase in tached leaf and dormant lateral plants with this method. This bud. Single-eye cuttings require Conventional Stock may be the most efficient use of 2 to 3 weeks longer to reach a Production greenhouse space for small- to flowering stage. Using this method, you can medium-sized growers and re- pot cuttings into large or small quires no special skills in devel- Rooting Medium oping stock plants. containers from May to August, Geraniums can be rooted in depending on the number of Spraying ethephon (Florel) a variety of media including con- cuttings you want to obtain over on stock plants increases the ventional peat-lite medium, the life of the stock plant. Four cutting number by 20 to 30 per- strips containing peat, special- weeks after potting or when the cent and retards growth, reduc- ized cubes, trays, rock wool, or cuttings are 6 inches tall, give ing internode length and leaf other synthetics. These may in- the cuttings a soft pinch. This size as well as delaying flower clude cell-packs, Jiffy strips, will cause the cutting to develop development. Apply it at a rate Oasis blocks, or Jiffy pellets. three to five lateral shoots. Take of 350 to 500 ppm after pinching Regardless, make sure the root- cuttings every 2 weeks there- or after removing cuttings. ing medium is exceptionally after, leaving three to four nodes Applying ethephon just before well-aerated, well-drained, and on the lateral shoots for addi- removing cuttings may increase sterile, with a pH of 5.8 to 6.2. tional shoots. These early cut- rooting. Some sources recommend using tings are often discarded. The environmental and nutri- a rooting hormone; others do Remove all flower buds and tional condition of the stock not. It appears that rooting hor- large leaves when you remove plants can have a big impact on mone can benefit slow-rooting cuttings. Completely defoliate all the rooting of cuttings. Oversuc- cultivars and cuttings from poor- stock plants in November or culent cuttings do not root well. ly managed stock plants. If you December to allow light into the Therefore, provide moderate choose to use a hormone, 500 plants and to reduce ARCHIVEpotential moisture and temperature with ppm Indolebutyric acid (IBA) disease problems. Harvest cut- high light for optimum cutting works well. Do not dip cuttings tings for the finished crops from results. You will obtain the high- into hormone solution or pow- January through March. est rooting percentage from der. Use a puff-duster to apply stock plants that receive a medi- powders to the cutting bases, or um level of nitrogen and higher use a mister to apply liquids. levels of phosphorus and potas- You can also dip cuttings in sium. 2,500 to 5,000 ppm B-Nine the day before sticking to help speed rooting.

3 Spacing point, start with 5 seconds on Watering Stick the cuttings into the every 5 minutes on the first day. Water newly potted cuttings rooting medium 1⁄4 to 1⁄2 inch Watch the foliage, and adjust the two or three times the first day deep, but no deeper. Space rate as needed. Decrease the to ensure complete saturation of geranium cuttings so the leaves mist interval until misting ends the medium. Apply enough of adjacent cuttings do not over- by day 18. Mist at night for the water so that 10 to 15 percent of lap. Use about 2 inches between first 6 days at 5 seconds on every the total volume drips from the cuttings, or 22 to 36 cuttings per hour. bottom of the container. square foot. Because Botrytis can Afterward, water whenever the be a serious problem in propa- Fertilization medium surface lightens in color gation, adequate spacing and ex- Do not fertilize the cuttings and the pots feel light in weight. cellent ventilation are essential. until roots are present. However, The best time to water is in the as soon as roots appear, begin morning when the temperature Temperature fertilizing with 250 to 300 ppm of is increasing so that foliage dries The most rapid rooting oc- nitrogen and potassium. as quickly as possible. Many curs with a 60° to 62°F night growers use an automated wa- temperature in combination with “Fast-Cropping” tering system, such as microtube irrigation or ebb-and-flow, when 68° to 72°F bottom or medium Geraniums heat. Try to keep day tempera- plants are placed at final spac- ture in the 75° to 80°F range. Profitable geranium produc- ing. tion depends on finishing as Light many crops as possible in a Temperature given greenhouse area in the Optimal day temperatures Geranium cuttings need high shortest time possible. This cul- light during propagation but can depend on light intensity. On tural procedure is used to pro- bright days, begin ventilation at benefit from some shade late in 1 duce a 4- to 4 ⁄2-inch-pot gerani- 75° to 80°F with a night temper- the spring to control tempera- um from a rooted cutting with ture. In propagation, be sure ature of 65°F. On cloudy, over- one flower open in about 6 cast days, begin ventilation at light levels are 1,800 to 2,800 weeks. Procedures are exacting footcandles until roots form (12 72°F. Bottom heat to a 70° to and require exceptional attention 72°F medium temperature pro- to 18 days), then 2,800 to 3,600 to detail. footcandles until transplant. motes rapid root growth, espe- cially just after potting. Night Potting temperature should be 65° F Scheduling Pot rooted cuttings 6 weeks with a 70° to 72°F media tem- Under ideal conditions and before sale in a peat-lite medium perature. depending on the cultivar, cal- with at least 80 percent total luses should form on the basal porosity. You can use a commer- Light end of the cuttings in about 5 cially available mix or prepare Provide full sun as long as days. Roots should appear at the one yourself. Medium compo- temperatures can be maintained base of the cuttings about 12 to nents may include sphagnum at less than 85°F. Too much light 18 days after sticking. Cuttings peat moss, vermiculite, perlite, and high temperatures can cause are usually ready to transplant in aged pine bark, or calcined clay. foliage to wilt in early afternoon, 3 to 4 weeks. In a mix-your-own medium, add even if the medium is moist, and dolomitic limestone to a pH of 1 can cause reddening of the peti- Mist 5.8 to 6.2, superphosphate at 4 ⁄2 oles and stems. You may need to Mist intervals vary with the pounds per cubic yard, and a shade the greenhouse glazing condition of the cuttings, time of commercial micronutrient formu- during late spring and summer. ARCHIVElation according to the manufac- year, environmental conditions, Light intensity that is too low and performance of the misting turer’s recommendation. causes stems to stretch, light-col- equipment. The goal, however, Unrooted cuttings can be direct- ored soft growth, and delayed is to maintain foliage turgidity stuck in pots and rooted under flowering. with a minimum amount of fo- mist to finish in 10 weeks. liage wetting. There should be Maintain the plants pot-to-pot for little or no runoff into the propa- 3 to 4 weeks, and then space gation medium. As a beginning them at four plants per square foot.

4 Fertilizer Zonal Geraniums for Greenhouse Production in the Southeast* Use a constant liquid feed of Cultivar Color Source 15-15-15 or 15-0-15 at 250 ppm American Red Red/scarlet Ball Seed Co. nitrogen with one clear watering American Rose Splash Red/scarlet Ball Seed Co. Designer Red Red/scarlet Ball Seed Co. per week to prevent soluble salts Designer Bright Red Red/scarlet Ball Seed Co. buildup. Avoid soluble fertilizers Satisfaction Red Red/scarlet Ball Seed Co. with more than 40 percent of the Satisfaction Bright Red Red/scarlet Ball Seed Co. total nitrogen in the ammonium Showcase Scarlet Red/scarlet Ball Seed Co. and urea forms, such as some Atlants 96 Red/scarlet Fischer USA, Inc. Diabolo Red/scarlet Fischer USA, Inc. 20-20-20 fertilizers. A monthly Grand Prix Red/scarlet Fischer USA, Inc. drench application of Epsom Rumba Red/scarlet Fischer USA, Inc. salts (magnesium sulfate) at 16 Samba Red/scarlet Fischer USA, Inc. ounces per gallon may be need- Tango Red/scarlet Fischer USA, Inc. ed to prevent magnesium defi- Tango Dark Red Red/scarlet Fischer USA, Inc. Medallion Dark Red Red/scarlet Oglevee, Ltd. ciency. Sassy Dark Red Red/scarlet Oglevee, Ltd. Kim Red/scarlet Oglevee, Ltd. Growth Retardant Ritz Red/scarlet Oglevee, Ltd. Sincerely Yours Red/scarlet Oglevee, Ltd. Cycocel (chlormequat) is the Melody Red Red/scarlet Oglevee, Ltd. growth retardant commonly used Designer Bright Lilac Lavender/magenta/purple Ball Seed Co. on geraniums to reduce final Designer Lilac Chaffon Lavender/magenta/purple Ball Seed Co. height. Rates vary from 750 to Designer Purple Rose Lavender/magenta/purple Ball Seed Co. 1,500 ppm, depending on the Satisfaction Bright Lilac Lavender/magenta/purple Ball Seed Co. Calypso Lavender/magenta/purple Fischer USA, Inc. application method, cultivar Disco Lavender/magenta/purple Fischer USA, Inc. vigor, and environmental condi- Kardino Lavender/magenta/purple Fischer USA, Inc. tions. A 1,500 ppm spray is ap- Tango Violet Lavender/magenta/purple Fischer USA, Inc. plied 14 days after planting, with Tiffany Lavender/magenta/purple Fischer USA, Inc. a second application 14 days Aurora Lavender/magenta/purple Oglevee, Ltd. Fox Lavender/magenta/purple Oglevee, Ltd. later only if needed on vigorous Laura Lavender/magentapurple Oglevee, Ltd. cultivars. Some growers prefer to Veronica Lavender/magenta/purple Oglevee, Ltd. use 750 ppm beginning 14 days Designer Hot Coral Pink/salmon Ball Seed Co. after planting and additionally 3 Designer Salmon Rose Pink/salmon Ball Seed Co. to 4 times at weekly intervals as Satisfaction Pink Pink/salmon Ball Seed Co. Satisfaction Hot Pink Pink/salmon Ball Seed Co. needed. Apply only to well-wa- Satisfaction Salmon Pink/salmon Ball Seed Co. tered, unstressed plants early in Showcase Salmon Pink/salmon Ball Seed Co. the morning or on cloudy days. Bravo Pink/salmon Fischer USA, Inc. Spray a light mist or until the Bravo Light Pink Pink/salmon Fischer USA, Inc. leaves glisten, never to runoff. Charmant Pink/salmon Fischer USA, Inc. Dolce Vita Pink/salmon Fischer USA, Inc. This can be accomplished by ap- Gloria Pink/salmon Fischer USA, Inc. 1 plying ⁄2 gallon of solution per Helena Pink/salmon Fischer USA, Inc. 100 square feet of bench area. Montevilleo Pink/salmon Fischer USA, Inc. Even under the best conditions, Rokoko Pink/salmon Fischer USA, Inc. Cycocel may cause some foliar Schoene Helena Pink/salmon Fischer USA, Inc. Tango Light Salmon Pink.salmon Fischer USA, Inc. yellowing on younger leaves, Evening Glow Pink/salmon Oglevee, Ltd. particularly at higher rates. Plants Peaches Pink/salmon Oglevee, Ltd. should recover in a few weeks. Patriot Salmon Blush Pink/salmon Oglevee, Ltd. Patriot Bright Pink Pink/salmon Oglevee, Ltd. Pests Patriot Light Pink Pink/salmon Oglevee, Ltd. ARCHIVESarah Pink/salmon Oglevee, Ltd. Whiteflies, aphids, spider Melody Pink/salmon Oglevee, Ltd. mites, fungus gnats, and caterpil- Lollipop Pink/salmon Oglevee, Ltd. Lotus White Fischer USA, Inc. lars can all be problems on gera- White Truffle White Oglevee, Ltd. niums. In recent years, whiteflies North Star White Oglevee, Ltd. have been a persistent and diffi- Raspberry Ice White Oglevee, Ltd. cult problem to control. * Cultivar information provided by Ball Seed Co., West Chicago, IL; Fischer USA, Inc., Boulder, CO; Oglevee, Ltd., Connellsville, PA.

5 Diseases Additional Reading The list of diseases that can Ball, V., ed. 1998. be a problem on geraniums is Pelargonium x hortorum (Zonal extensive and includes bacterial Geraniums). Ball Redbook, 16th blight, blackleg, Alternaria leaf ed. 657-675. Ball Publishing, spot, bacterial fasciation, cutting Batavia, Illinois. rots, cottony stem rot, black root Larson, R.A., ed. 1992. rot, rusts, bacterial leaf blight, Geraniums. In Introduction to Verticillium wilt, Southern Floriculture, 2nd ed. 451-475. blight, and numerous viral dis- Academic Press, Inc., San Diego, eases. California. Specific control measures for White, J.W. 1993. Geraniums insect and disease problems can IV. 4th ed. Ball Publishing, be found in Extension Circulars Batavia, Illinois. ANR-500A and ANR-500B, Alabama Pest Management Handbook, Volumes 1 and 2, or contact your county Extension agent.

ARCHIVE J.R. Kessler, Jr., Extension Horticulturist, Assistant Professor, Horticulture, Auburn University For more information, call your county Extension office. Look in your telephone di- rectory under your county’s name to find the number. Issued in furtherance of Cooperative Extension work in agriculture and home economics, Acts of May 8 and June 30, 1914, and other related acts, in cooperation with the U.S. Department of Agriculture. The Alabama Cooperative Extension System (Alabama A&M University and Auburn University) offers educational programs, materials, and equal opportunity employment to all people without regard to race, color, national origin, religion, ANR-1106 sex, age, veteran status, or disability. UPS, 5M13, New April 1998, ANR-1106