Few plants have created more of a sensation among gardeners and herbalists in recent years than coneflower (Echinacea). Numerous studies, primarily from Germany, suggest that use of this herb does indeed bolster immune systems. Health claims aside, gardeners wax eloquent over the plant's vigor and hardiness, and its long, midsummer-into-fall bloom season. Birds and butterflies also seek out the flowers.
The plant's botanical name comes from the Greek echinos, meaning "hedgehog," a reference to its sharp, pointed flower bracts. "Coneflower" is a reference to the flowers' raised or conical centers.
All nine species of coneflowers are native to North America, but only the four listed here are available commercially. All are widely adaptable, so they will likely thrive in your garden. Except where noted, all are cold hardy to -35°F (USDA Hardiness Zone 3). By the same token, coneflowers thrive in southern and mild regions, through zone 9 in both the East and West.
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.
Plant coneflower in a sunny location that has well-drained, fertile soil. Most can thrive on available rainfall once established, and plenty of sun and heat won't bother them. The long-blooming, colorful flowers are at home in sunny borders, herb gardens, cottage gardens, prairie gardens, or wild gardens.
Propagate by seed, or dig and divide the main rootstalk in spring or fall. Root division is an alternative for all species, but it is most successful with E. purpurea. The best time to divide roots is in early autumn or spring. Cut through the crown of the coneflower clump with a sharp spade. Separate two to three young roots and shoots from the main plant every 4 to 5 years.
Grow coneflower plants from seed following a dormancy-breaking period. Seeds germinate best between 70° and 75°F and, for E. purpurea, after dry prechilling (1 to 3 months at 40°F). Sow seeds indoors 6 to 8 weeks before the last frost date in your area; or sow on the surface of a sandy soil mix in an open cold frame in early spring. (See individual species descriptions for exceptions.) Seeds normally germinate within 10 to 20 days. Transplant seedlings outside after all danger of frost has passed. Coneflower self-sows readily but not aggressively.
In short-season regions, coneflowers may need more than one growing season to produce flowers unless seeds are started early indoors.
In northern areas (zones 3, 4, and 5), plants need to develop roots fast. Pinch off flower buds that develop the first year from seed. The plant will divert its energy into root development. In mild-winter areas, coneflower may grow and flower the first year from seeds sown in the garden.
To extend the flowering period of mature plants, cut off faded flower heads. However, toward season's end, you may want to leave some to dry out on the stems: They make attractive forms in winter, and their seeds attract many birds, especially finches.
Depending upon where you live, you may need to protect young plants from rabbits and groundhogs that find new shoots appetizing. The only other pests are leaf spot fungus and Japanese beetles, but neither is likely to kill the plant, so I recommend no treatment other than picking off the beetles. Caterpillars are known to defoliate coneflower plants. If you prefer the plants to the potential butterflies, use Bt (Bacillus thuringiensis) to control caterpillar infestation. Daily caterpillar picking is the butterfly-friendly alternative.
Native Americans considered coneflower an important medicinal plant. They applied crushed root pieces directly to venomous bites and stings, and they chewed on dried root to treat a variety of ailments. Modern herbalists agree that coneflower root is one of the best herbal remedies available to prevent, and reduce the severity of, colds and flu.
Both roots and aboveground parts of E. angustifolia and E. purpurea are the sources of most of the modern echinacea remedies, but the dried roots are used in homemade preparations. Powdered roots and tinctures are sold in health-food stores and some supermarkets.
Allow seed-started plants to grow for 3 to 4 years before harvesting roots; divided plants need two years. Dig them in the autumn after flowering is finished, and cut washed and dried roots that are thicker than 1/2-inch into sections to speed drying. Allow the roots to dry in a warm but shaded place. Replant the crown with smaller roots to continue your supply.
Prepare roots in either of these ways: Grind dried root pieces into a powder. Mix 4 tablespoons of powdered root per quart of water; cover and simmer over low heat for 20 minutes, then strain. Drink the solution hot or cool, 1 to 2 cups per day. The tea cannot be stored because it becomes unstable, which is why most herbalists prepare it in an alcohol tincture.
Make a tincture by covering washed, chopped, and dried root with 1 to 2 inches of 100-proof vodka in a clean glass jar that has an enamel cap. Allow it to steep at room temperature for two weeks, shaking the container daily. Proper dosage is an individual matter, and you should consult with a naturopathic physician or qualified herbalist before using any herb. Echinacea tincture is effective in very small amounts. Generally, half to one full eyedropper (30 to 60 drops) a day in water, juice, or tea is about right.
Coneflower's resilience, its rich history, its medicinal value, and its sturdy beauty make it an exceptional plant worthy of further study, cultivation, and appreciation.
Holly H. Shimizu is an herb garden specialist and the executive director of the U.S. Botanic Garden in Washington D.C.
Photography by Suzanne DeJohn/National Gardening Association
Article published on June 23, 2008.