Gardening Articles: Flowers :: Perennials
Coneflower (page 3 of 4)
by Holly Shimizu
How to Grow Coneflower
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.