$4.00 North Carolina ^gjgg^, Flower Growers' Bulletin Volume 44, Number 2 April, 1999

Official Publication of the North Carolina Commercial Flower Growers' Association

Growing Asian as Floricultural Crops

James L. Gibson, Graduate Research Assistant Brian E. Whipker, Floriculture Extension Specialist Raymond Cloyd, University of Illinois and Ron Jones, Ornamental Pathology Extension

Introduction by these leafy mustards are attractive A number of species in the Critciferae characteristics contributing to the life of cool family provide both nutritional value to our diet season gardens which do not display much color as well as showy landscape specimens in our during the months of October through March. gardens. Ornamental and kale has been The mild winter climate of the Southeast allows the standard ornamental for providing mustards to show attractive vegetation throughout colorful and attractive foliage during the winter the winter. months, but recently the presence of leafy Leafy vegetables like mustards and kales vegetables, in particular oriental mustards, has are some of the oldest cultivated crops in the been observed in the fall landscape. Leafy world. Mustards have been utilized in the Far mustards which have been used for years as East and for more than 2,000 years as a edible components in salads and stir-fry dishes source of oil, medicines, fodder for cattle, and are now being adopted by curators of botanical condiments (Knott and Deanon, 1967). Mustard gardens, landscape contractors, and greenhouse leaves are tender and tasty and contain an growers as attractive and profitable items. These abundance of vitamins and minerals. The seeds vegetables are being used as specimen , are rich in oil and proteins. Today's society has border plants, and are used in mass plantings in incorporated these plants into gardens which wintergardens at conservatories and arboretums, provide color during the winter months. The shopping center entranceways, and community mustard's robust attractive foliage, whether it be gardens. Planted with fall pansies and garden curly, crinkled or smooth, is an asset to the mums, these vegetables offer texture and foliar dormant shrub or perennial garden. The presence color. The shades of green and purple provided of brilliant yellow flowers in early spring after

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their elongated stalk has developed, provides appearance as well. Temperatures below 15°F addition color with flowering bulbs and pansies. (-9.4°C) can cause the unprotected outer leaves Kales of different leaf morphology and to become shriveled and damaged. The interior genetic variability are also used in the winter leaves of this biennial can survive low landscape. Ornamental cabbage and kale are temperatures, but the entire plant can be reduced popular as fall crops because they have colorful, to only 5 to 6 leaves. These plants will regrow long lastingfoliage (see HorticultureInformation whenwarmweatherreturns. Tolimitcold injury, Leaflet Number 507 for additional production the plants should be planted under trees or in information). Other types of kales, which are wind protected areas. Red mustard can achieve used in the landscape are Russian red kale, a height of three feet as long as winters remain dinosaurkale, andredborkale. Swisschard, with warm and wet. The tall mounding growth habit its brilliant green and red foliage and stems, has makes 'Red Giant' an attractive specimen plantor also been adopted as a specimen plant in the background texture plant. winter garden. ' { rapa var. rosularis) is similarto the popularAsian vegetable, packchoi. Cultivars The leaves are flat, shiny, and broad and the leaf Three cultivars were studied at NC State margins are smooth. Thefleshy dark-green leaves University in Raleigh. Each variety possesses are firm and the white petioles attach to a central different characteristics such as form, leafshape, growing point forming a rosette. The low growing leaf color, and bolting potential. All varieties habit of 'Tatsoi', makes the plant an attractive requirehigh amountsofirrigationand fertilization. border plant in winter gardens. Planting of this Their performance has been evaluated in soilless type of mustard-spinach in mass is suggested substrate in both the greenhouse and outdoors, (Farmer, 1998). Tatsoi' does not survive and they have also been evaluated over time in temperatures lower than 25°F (-4°C) and is the garden. The varieties observed are described reduced to blacked tissue as a result ofexposure below. to low temperatures. It has a short vernalization India mustard or red mustard {Brassica requirement and bolts rapidly as temperatures juncea var. rugosa) is a large leaved, thickpetioled begin to increase in the spring. 'Tatsoi', with its mustardwhich outperformedthe othervegetables small compact form, can be grown with a tight in garden appeal. The cultivar 'Red Giant' is spacing. Like the red mustard, 'Tatsoi' requires attractive in both foliage size and shape. The constant irrigation and fertilization. large bronzed blades become more intense in The final leafy vegetable studied, 'Early color as the plant matures and the application of ' {Brassica rapa var. nipposinica) is also plant growth regulators enhances the color called potherb mustard and is a popularvegetable intensity. The plant's rapid growth and intense which is used in salads and stir-fry dishes leaf color enable growers to market the plants (Stephens, 1988). This plant is used as a specimen shortly after transplanting, 5 weeks earlier than item in the landscape as well as a groundcover. ornamental cabbage and kale. The leaf blades 'Early Mizuna' grows in the form ofa mound and taper down to the main growing point which is may reach a height of two feet. The leaves are thick and fleshy, the roots are fibrous and water yellow-green and deeply notched. The feathery requirements are greatas the root mass develops. leaved plant may possess up to 180 leaves and all The midribs are bright white and as the plant petioles are attached to a thick, tan stem. The reaches full maturity the "meat" of the blade plant may survive light frosts, but is killed by changes from a rusty red to a reddish black color. sub-freezing weather. The plant, after the The plant's leaves convert from a dull to a shiny vernalization period has been achieved, can N.C. Flower Growers' Bulletin - April, 1999 Volume 44, Number 2 produce several elongated stalks, which harbor These vegetables are heavy feeders and the reproductive structures. 'Early Mizuna' is competitionfornutrientsshouldbeavoided.Seeds very attractive in bloom, as several bright yellow can also be sown in the final containers and then flowers cover the plant. thinned when the seedlings begin to produce true leaves, or seeds can be sown in plug trays. It is Scheduling common for southern growers to purchase plugs Mustard plants generally require 6 to 8 (typically 128s or 162s) from northern plug weeks of growth to achieve marketable size in 1 producers. Some northern plug producers are gallon or 8" mum pans. Due to their rapid growth now adding mustards into their plug production rate, mustards can be ofwholesale shipping size scheme. If growers decide to sow these leafy by 6 weeks, and retailers can market the crop in vegetables themselves, germination substrate 8 weeks. A typical production schedule is listed needs to remain cool and moist. An application of in Table 1. B-Ninetwo weeks aftersowingshouldbe applied at 2,500 ppm to control plant height in the plug Seeding, Containers, and Transplanting tray. Germination takes around 3 to 5 days at 70°F with the seeds being lightly covered with a Spacing germinationmix.Seedscan besowninplugflats, Due to theirrobustfoliage, mustardplants germination trays, or into a 606 or an 806 flat. should be spaced in order to maximize airflow, The plants should not be allowed to become root which prevents foliar diseases, and it allows for bound in the germination container before uniform growth around the pot. If plants are to be transplanting,asrestrictionofthe rootswillresult established in greenhouses, one should take extra in stunted plant growth. The seedlings should be care in watering, spraying, and shifting plants, transplantedinto largerpots capableof holdinga because the foliage may be fragile when large amount of substrate with excellent water temperatures are warm. Use 6" centers for 4" holding capacity. The plugs are transplanted pots, ll"to 12"centersfor6"pots,and 16"to 18" when the rootballs are fully developed and the centers for 1 gallon or 8" mum pans. first true leaves are twice as large as the cotyledons. If the plants have become too tall in the seedling flats, Table 1. Typical North Carolina ornamental mustard production theycan beplanted schedule for an 8" mum pan. deeper (up to the Time Cultural Practice first set of leaves) in the final pot. Sow seeds into plug flats and grow out WeekO Growers are Fertilize at the rate of 50 to 100 ppm N and K after seedlings emerge commonly Transplant the plugs into 8" mum pan producing Asian Fertilize at the rate of 150 to 250 ppm N and K vegetables in 6,7, Weeks 3-5 or 8 inch pots. Applypreventive fungicide drench For Apply insecticides as needed maximumgrowth, Respace plants if needed growers should Weeks 6-8 Acclimate plants to cooler temperatures if greenhouse grown transplant one seedling per pot. Decrease fertilizer to 100 ppm N and K N.C. Flower Growers' Bulletin - April, 1999 Volume 44, Number 2

Root Substrate, Irrigation and Nutrition result inyellowing (nitrogen deficiency), purpling RootSubstrate(Medium). Plants can be grown (phosphorus deficiency), or defoliation of the in a good quality soilless substrate, which has basal leaves. Deficiency symptoms are more good water holding capacity. If the plants are to likely to occur in a soilless substrate, which has be grown outdoors in pots, a soil based substrate a low cation exchange capacity (the ability to or the addition of sand may help avoid toppled hold nutrients). Therefore, for the final two plants during windy weather. weeks of growth, a fertilization rate of 100 ppm N and K should be sufficient while allowing the Irrigation. During the summer months, when plants to develop color and avoid deficiency the plants are establishing themselves in pots,an symptoms. adequate supply of water should be provided to the substrate. Use of an automated drip watering Growth Regulators system similar to one used on garden In order for growers to achieve chrysanthemums is recommended. Mustards are profitability from the sale ofornamental mustards, not tolerant of water stress, which results in the the aesthetic appeal of the crop should be of stallingofplantgrowth,yellowing,anddropping primary concern. The ratio of pot to vegetation of lower leaves. Premature bolting can occur if must be maintained and stretching must be moisture levels become low in the substrate and avoided. Plant growth regulators (PGRs) can be extensive wilting takes place. used to achieve desired wholesale and retail heights and diameters. PGRs can only be applied Nutrition. Maintain the root substrate pH to mustards grown as a non-food crop. A PGR between 5.8 and 6.5. Irrigation water alkalinity study was conducted at NC State University on levels should be around 2 meq/L of alkalinity the leafy mustards 'Tatsoi', 'Early Mizuna', and (100 ppm CaC03 or 120 ppm HC03") toavoid a 'Red Giant'. 'Tatsoi' is a low growing plant and general increase in pH over the growing season. PGRs are not needed for height control. Single Ifalkalinity levelsarehigher,considerusingacid applications of B-Nine at 2,500 or 5,000 ppm injection or an acidic fertilizer (as long as the were not effective in controlling height of 'Early N03-N to NH4-N ratio is greater than 2:1). Mizuna' or 'Red Giant', but both B-Nine rates Fertilize the plants with a balanced fertilizer of were effective in controlling plant diameter. To calcium nitrate (Ca(N03)2) and potassium nitrate control plant height of 'Early Mizuna' or 'Red (KNO,), with periodic applications of 20-10-20 Giant', multiple B-Nine applications at 2,500 and or 21-5-20 (for phosphorus and micronutrients) 5,000 ppm would be required. A second PGR and MgS04-7H20 (for magnesium and sulfur). study was conducted on 'Red Giant' using a High levels of NH4-N + urea in a fertilizer mix single higher rate of B-Nine (up to 10,000ppm) will stimulate stem elongation, resulting in the andB-NinewithCycocelasa"tankmix". Higher need for higher plant growth regulator rates to rates of B-Nine at 7,500 or 10,000ppm provided control plant growth. For the seedling stage, no additional control of plant height or diameter. fertilize at the rate of 50 to 100ppm of N witha The additionof Cycocelto the B-Ninealsogave constantliquid feed. After transplantinginto the little additional control. Phytotoxity along the final container, fertilize with a balanced fertilizer margins of the leaf was observed with Cycocel at the rate of 150 to 250 ppm N and K. Electrical concentrations of3,000ppm.Onceagain,multiple conductivity (EC) should be maintained between applications of B-Nineat 2,500 or 5,000 ppm to 1.0 and 2.5 mS/cm during periods of active 'RedGiant' aresuggested andperiodic monitoring growth. Excessivefertilization willpreventgood of plant height and leaf expansion should be coloration, but deficient levels of fertility will followed to determine the proper application N.C. Flower Growers' Bulletin - April. 1999 Volume 44, Number 2

schedule. The use of PGRs not only controls the Insects and Diseases amount of internodal stretch and leafexpansion, A number of insects and diseases can but it also enhances the bronze appearance of attack ornamental mustards. A descriptive listing 'Red Giant'. of insect and disease pests and management strategies are listed in Table 2 and Table 3. Temperatures {Mention of chemical trade names does not During the late summer, the large leaved constitute an endorsement. Ommission of any mustard varieties should be lightly misted during registered chemical does not imply criticism.) the day when the light and temperature are intense. Optimal growth occurs with plants of the For Further Reading Cruciferae family grown in outdoor production Farmer, J. 1998. Cool Veggies. American Nurseryman. (Whipkeretal., 1998). When plants are grown in L88(l):30-36. Knott. J. and J.R. Deanon. 1967. Vegetable Production is greenhouses, nighttime temperatures should be Southeast Asia. Univ. of the Phillipines. pp. 366. held at 55 to 60°F during the final 4 weeks of Stephens. J.M. 1988. Mustard, p. 72. In: J.M. Stephens. production. The cooler temperatures will avoid Manual of Minor Vegetables. Univ. of Florida Coop. Ext. the plant from becoming to "soft" and fragile and Serv., SP-40. will allow the plant to harden and become Whipker, B.E., J.L. Gibson, R.A. Cloyd, C.R. Campbell, and R. Jones. 1998. Success with ornamental cabbage and acclimated to much cooleroutdoor temperatures. kale. NCSU Horticulture Information Leaflet 507.

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