Production of Eryngium John Njenga Department of Horticultural Science, NCSU (John Njenga Is Currently Agraduate Student in Our Department Working with Dr

N.C. Flower Growers' Bulletin - August, 1995 Volume 40, Number 4

Production of Eryngium John Njenga Department of Horticultural Science, NCSU (John Njenga is currently agraduate student in our department working with Dr. Roy Larson on his Master's degree. John is researching cutflower production oferyngium with an emphasis in propagation.) AlpineSeaHollybelongstothefamily E. alpinum —This species is about 2 feet high, Umbelliferae (Apiaceae) in the has a bushy growth habit, and has 10 to 20 genus Eryngium (Atwater, 1980). bracts per inflorescence. The leaves are The common name is Alpine Sea Holly but it is triangular, heart shaped and bluish in color. alsoreferredtoasEryngium. The'name Eryngium The upper leaves maybe trilobed. The flower is from eringion, an old Greek name for a thistle heads are bluish purple. There is also a white which some of the species' appearance seems to variety. Hardy at-20 to-10 °F. suggest. The plant is a herb with spiny leaveson E. amethystinum-Grov/sto about 2 feet. Leaves the margins. The leavesare simplecut or lobed are compound and deeply lobed. Flower (Taylor, 1983). Eryngium is an excellent cut headsare bluish purple incolor and are usually flower. There are several species which are V2 inch long. Bracts are lance or pinnatifid in suitable for use as cut flowers (Sansone, 1994). shape. Hardy at -20 to -10 °F. Eryngium is a hardy perennialplantof great E. aquanticum -- A stout, bushy herb, growing 4 decorative value which grows from 2 to 3 feet to 6 feet high. The leaves are stiff and very highduringthe summermonths (Everett, 1960). narrow. The flower heads are pale blue or Aside from their use as a cut flower, sea hollies whitish. Hardy at-20 to-10 °F. are also widely cultivated for the border or rock E. bourgati—The plant is hardly over 18 inches gardens (Everett, 1960). high. The leaves are almost round, stiff, spinytoothedanddividedinto 3to 5segments. Inflorescence Description The flower heads are lh inch long and bluish Eryngium has small flowers arranged in a purple. Hardy at -20 to -10 °F. tight globose head and each inflorescence is E. giganteum ~ This species grows 5 to 7 feet subtended by showy bracts (Armitage, 1993). high. The leaves are much branched or heart The bloomhead is somewhat thistle like. Leaves shaped. Theupperleavesare trilobed. Flower are also ornamental (Everett, 1960). Flowers are headsare almost4 inches wideandtheircolor mainly blue in the cultivated varieties, but also is blue or pale green. Bracts are long and canbe white or green. The bloomcalyx is showy green. Hardy at-10 to 0 °F. and spiny toothed. The petals which are usually E.oliverianum—Usually 2 to 3 feet high. Leaves notconspicuous, are erect and stiff. Most cultivars are undivided and upper ones are in 4 to 5 are summer blooming (Taylor, 1983). parts. The flower heads are 1 xh inches wide, blue or bluish purple in color. This species is Popular Species and Their Characteristics of unknown hybrid origin. Hardy at -20 to Eryngium is found wild chiefly in Southern -10 °F. Europe but some are native to North America. E. planum - Usually less than 3 feet high. The Eryngium aquanticum is a native ofnortheastern leaves are undivided and the upper are 3 to 5 United States. The genus has over 200 species parts. The flower heads are blue and are but the seven listed in the next column are the about 72 inch wide. The bracts are rigid and most popular (Taylor, 1983): very narrow. Hardy at -30 to -20 °F. N.C. Flower Growers' Bulletin - August, 1995 Volume 40, Number 4

Propagation greenhouses. The crop can also tolerate hot Eryngium is commonly propagated by seed. summers (Armitage, 1993). Shadingexperiments It can also be multiplied by division where the have shown that field performance is reduced by plantlets growing at the base of the plant are shade although flower color is improved carefully transplanted and also by cuttings. (Armitage, 1991). (Table 1). Maturerootcuttingsof2 to 4 inches long sections Plants grown South of Zone 5 are of poor will root when placed in a moistporous substrate quality than those grown in more northern zones at warm temperatures of 68 to 75 °F (Armitage, 1993). The weakness ofSea Hollies is that they Table 1. The effect of shade on yield and are slow to recover from the shock of division, stem length ofEryngium planum in the third dislike being disturbed and are rather slow to year of production.* establish after transplant. This is the reason why it may be better to set them out where they are Percent Yield Scape likely to remain (Everett, 1960). shade (stems/plant) length (cm) When propagating eryngium from seed, the 0 8.6 84.0 seed shouldbe ripe before it is collected. Freshly 55 4.2 86.7 harvested seed should be sown immediately. 67 0.4 109.5 Seeds of Eryngium become dormant soon after *From Armitage, 1989b. harvest. The main block to germination ofseeds in this genus is the delay in embryo maturation which are ofhigh quality but have shorter stems which is enhanced by the presence of inhibitors (Armitage, 1993). until they are leached or neutralized (Atwater, Since Eryngium is a perennial crop it can last 1980). Research conducted at the University of for several years in the field, however, for Georgia emphasizes the need to use fresh seed. commercialproduction, 3 to 5 yearsis the average Seeds of Eryngium planum germinate readily life span employed because the yield starts to when fresh, however, it may take several months decline thereafter. Although yield declines with for seedlings to emerge, and many seed will not plant age, the stem length and diameter are not germinate at all if they are not fresh (Pinnel et al., affected. Acloser spacing of 18inches is used for 1985). The germination ofEryngium alpinum is plants rotated every 3 years, and a wider spacing less uniform and much slower than that of of 3feet is used for plants that will be grown more Eryngium planum. than 3 years in the field. Crop production under shade cloth is good for preventing rain damage Cultural Requirements but as already stated there is yield reduction Sea Hollies thrive best in well drained, light following the provision of shade. Field foliar and sandy soils (Everett, 1960). However, heavy analysesdone by Armitage (1993) have resulted clayscanbe madesuitableby diggingandmixing inthefollowingsuggestedoptimumfoliarnutrient ingravel, sandandcompost(Everett, 1960). The levels: 4.05% N, 0.63% P, 3.36% K, 1.19% Ca, substrate should be kept reasonably moist during 0.47% Mg, 257 ppm Fe, 84 ppm Mn, 28 ppm B, production (Taylor, 1983). Sea Hollies can and 61 ppmZn. tolerate saline soil conditions and they are fairly cold hardy. For flowering they require chilling Post Harvest temperatures of 40 °F or below. These Cut Eryngium flower stems can be used environmental conditions can be met by field either fresh or dried. Eryngiumwas listed among production, cold frames protection (in colder thetop 30flowers for drying (Armitage, 1991). climates), or production in minimally heated Harvesting should bedonewhentheentireflower

10 N.C. Flower Growers' Bulletin - August, 1995 Volume 40, Number 4

head including the bracts turn blue (Armitage, Armitage, A. 1991. Stage offlower development 1993), as soon as the whole bloom is open at harvest. The Cut Flower Quarterly (Armitage, 1989b). Eryngium planum can 3(1):13. produce flower stems of 3 feet long easily, and Armitage, A.M. 1993. Specialty cut flowers. flower heads ofabout 3A inch long. Cut stems of Varsity Press, Timber Press. Portland, E. planum and E. amethystinum areeasy to ship, Oregon. keep long in the vase and dry well ( Armitage, Atwater, B.R. 1980. Germination, dormancy ,1989a). Placing flowers in 40 °F coolers and morphology ofthe seeds ofherbaceous intensifies the color. Flowers persist for months ornamental plants. SeedSci. &Technol. 8: in a water vase though the foliage lasts only 7 to 523-573. 10 days (Whynman, 1993). The stems may be Everett,T.H. 1960. Newillustratedencyclopedia stored at 38 to 40 °F for 7 to 10 days. Though of gardening unabridged. Vol. 2 Greystone drying in the air is quite successful,morecoloris Press. New York. preservedby use of a desiccantsuchas silicagel Pinnel, M.M, A.M, Armitage, and D. Seaborn. (Armitage, 1993). 1985. Germination needs of common perennial seed. Univ. of Georgia, College Marketing of Agriculture, Experiment Stations. In 1993 dried Eryngium were selling at $2.75 Research Bulletin 331. per bunch wholesale, while the retail price was Sansone, P. 1994. Field trials: lemons and $2 to $4 a bunch of 10 stems. A field bunch was lemonade. The Cut Flower Quarterly. $ 3.30 wholesale price (Whynman, 1993). 6(1):6. Taylor, N. 1983. The garden dictionary. An Literature Cited Encyclopedia of Practical Horticulture. Armitage, A. 1989a. Notes on eryngium. The GardenManagementandLandscape Design. Cut Flower Quarterly. 1(2): 10. Boston and New York. Houton Mifflin Armitage, A. 1989b. The influence of shade on Company. The Riverside Press Cambridge. field grown crops. The Cut Flower Whynman, A. 1993. Pricing profile. The Cut Quarterly. 1(3):4. Flower Quarterly. 5(3):6.

Calendar OF Events

Event Date Time Location and contacts

PPGA International Bedding Saturday-Thursday San Jose Convention Center, San Plant Conference 30 Sept.-5 Oct. Jose, California. Contact PPGA at 800-647-7742 for further information.

Association of Specialty Wednesday-Sunday Omni Inner Harbor Hotel, Baltimore, Cut Flower Growers 1995 25-29 October Maryland. Contact ASCFG at National Conference 216-774-2887 for more details.

NCSU Poinsettia Wednesday 10:00 am Horticulture Field Laboratory, Raleigh, Open House 29 November to 3:00 pm N.C. Contact Roy Larson at 919-515- 3133.