Gardening Articles: Flowers :: Perennials
Coneflower (page 2 of 4)
by Holly Shimizu
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Petals of 'White Swan' don't droop like typical conflowers.
Black Sampson coneflower (E. angustifolia), also called narrow-leaved purple coneflower. Native to the Great Plains from the United States-Canada border west to Montana and Wyoming and south to Texas, this species grows only 10 to 24 inches tall (other species reach 2 to 4 feet). The light purple to rose pink flowers are 2 1/2 to 3 inches in diameter. Its leaves are narrow, and the stems are hairy.
Propagate by seeds sown in fall in a moist, sandy soil mix. Allow to overwinter in a cold frame. According to Neil Diboll of Prairie Nursery, this "moist stratification" procedure yields a significantly higher germination rate (about 90 percent) than seeding in a cold frame in early spring. If you cannot sow seeds in the fall, provide an artificial moist stratification: Mix seed in a 3-to-1 ratio with damp (not dripping wet) peat moss. Place the mixture in an airtight and watertight bag or jar marked with the date and plant name, and place it in the refrigerator at 34° to 38°F for 30 to 60 days.
Root division is possible. However, this species has a taproot, and unless the lower half of the root has buds, the process is less reliable for propagation compared with E. purpurea.
Researchers consider the roots of this species to have the best medicinal properties of all the coneflowers. But the plant's virtue may be its downfall: Collection of wild plants has increased to a degree that threatens their survival.
Pale Purple Coneflower (E. pallida). This species is found in sunny, well-drained sites from Illinois to Iowa and eastern Kansas and south to Georgia and Louisiana. Its 3- to 6-inch-diameter flowers are notable for their reflexed (drooping) petals. Bloom begins in midsummer and lasts until frost. Plants grow 3 to 3-1/2 feet tall. As with black Sampson coneflower, propagation by root division is rarely successful, so propagate this species by seed after moist stratification.
Purple Coneflower (E. purpurea). This is the most familiar and widely distributed of all coneflowers, and the one that most gardeners plant. Given rich, amended soil, plants reach a robust 3 to 4 feet in height and produce flowers 4 to 6 inches across. The reddish purple petals are shaded green at the tips, and the center is orange. In most varieties, the petals droop after growing outward from the cone, accounting for the name given to the plants in the Ozarks: droops. The 2- to 3-inch-long leaves are medium green, and toothed or smooth, dep on the variety. With their strong stems, they make an excellent addition to cut-flower arrangements. This coneflower, native to the open woods and prairies of Ohio and Iowa south to Louisiana and Georgia, makes a showy backdrop for low-growing summer annuals or perennials.
Unlike most of the other species, purple coneflower has a more fibrous root system, the reason it is more successfully propagated by division. If grown from seed, E. purpurea often blooms the first year.
Varieties of E. purpurea include: 'Alba'-creamy white flowers with coppery tones; 'Bright Star' -- red to rose flowers, flatter and less drooping than some coneflower varieties; 'Magnus' -- extraordinarily showy, with broad, flat pink petals around a brown cone, and chosen as perennial plant of the year for 1998 by the Perennial Plant Association; 'White Lustre' -- reflexed white petals around an orange cone; and 'White Swan' -- white flowers with a deep orange cone at the center; this variety comes true from seed.
Tennessee Coneflower (E. tennesseensis). This species is also on the endangered species list. Tennessee coneflower is known from only five natural populations in central Tennessee. (The United States Fish and Wildlife Service must license all nursery sources seeking to sell these plants in interstate commerce.)
The plants grow 2 to 3 feet tall. Flowers are deep pink with pinkish green centers and upturned petals, and leaves are medium to dark green and narrowly lance-shaped. Tennessee coneflower adapts well to cultivation and is easy to start from seed though it's not quite as cold-hardy as other coneflowers. I recommend it only as far north as zone 4.
Where to Buy
Seeds and plants are available from mail-order sources. Many nurseries offer 1-gallon plants in their perennial sections.