By Julie Christensen
Tickseed (Coreopsis) is the sort of perennial every gardener wishes for. These low-maintenance plants usually form in well-behaved clumps, tolerate a wide range of conditions and brighten the garden from summer to fall.
Common tickseed has yellow to orange flowers, many with double petals. Some varieties, such as ‘Goldfinch,’ are compact, growing 12 inches or less, while others, including ‘Baby Sun,’ grow 24 inches tall. These plants have lancelet-shaped green leaves and the flowers appear above slender stalks. Another variety, threadleaf coreopsis (C. verticillata) has light, airy foliage and smaller, more delicate flowers. It grows between 18 and 24 inches tall.
Most gardeners start tickseed from nursery transplants or divisions, but the plants grow readily from seed, as well. Sow them outdoors in spring or fall and cover them with only the lightest layer of soil. Keep in mind that some coreopsis hybrid varieties are sterile or will not grow true to seed.
Plant coreopsis in slightly moist, well-draining soil in full sun. Threadleaf varieties tolerate light shade, but most coreopsis varieties grow best in sun. Mulch the plants with 2 inches of organic mulch, such as wood chips, to conserve moisture and reduce weed growth. Remove faded flowers and cut coreopsis back midsummer if it becomes straggly.
Once established, coreopsis tolerates dry soil, but water it weekly during dry weather for better blooms. Fertilize coreopsis in the spring with an all-purpose plant fertilizer. As coreopsis matures, you might notice slowing growth. Occasionally, the centers of the plants might even begin to die out. If this happens, dig up the coreopsis plant in the spring and divide it. Replant the two parts, spacing them 30 inches apart, to rejuvenate its growth. Cut coreopsis back in late fall to 2 inches above the ground.
Pests and Disease
Coreopsis is fairly resistant to pests and diseases, but you might notice leaf spots or powdery mildew, especially in humid weather. To combat these problems, plant coreopsis so air circulates freely and opt for drip irrigation, rather than overhead sprinklers, since wet leaves spread disease. Remove any diseased plant material and discard it. Hand pick and destroy slugs and snails. Coreopsis is rarely bothered by deer, according to Rutgers University Cooperative Extension.
Varieties of Coreopsis to Consider
Coreopsis lanceolata is the type most people are familiar with. It grows in clumps and produces lancet green leaves. A few to try include:
- ‘Baby Sun,’ which has bright yellow flowers and grows 2 to 3 feet tall. Hardy in USDA plant hardiness zones 4 through 9.
- ‘Sunray’ has large, double flowers with heavily fringed edges. The plant grows 1 to 3 feet tall and blooms from early summer to fall. Although ‘Sunray’ is hardy in USDA zones 4 through 9, it is often short-lived. Allow it to self-sow or grow it as an annual.
- Coreopsis rosea produces bright pink flowers with yellow centers. Hardy in USDA zones 4 through 8, it needs more moisture than other coreopsis varieties.
- Coreopsis rosea ‘Sweet Dreams’ is only hardy in USDA zones 6 through 8; grow it as an annual elsewhere. Its chief attribute is its pale pink, daisy-like flowers with dark pink centers. This hybrid plant is sterile and does not produce seed.
Coreopsis verticillata, or threadleaf coreopsis, is lesser known, but still deserves a place in your garden. These plants have interesting foliage and a light, airy form. Consider:
- ‘Moonbeam,’ a compact plant with single, pale-yellow flowers. Hardy in USDA zones 4 through 9.
- ‘Golden Shower,’ produces bright yellow flowers and grows 3 feet tall. Hardy in USDA zones 3 through 9.
If you’d like to learn more about tickseed, visit the following sites:
Coreopsis from the National Gardening Association
Coreopsis Lanceleaf from Cornell University Home Gardening
Deadheading Coreopsis (video) from The Iowa Gardener
When she’s not writing about gardening, food and canning, Julie Christensen enjoys spending time in her gardens, which includes perennials, vegetables and fruit trees. She’s written hundreds of gardening articles for the Gardening Channel, Garden Guides and San Francisco Gate, as well as several e-books.