When to Plant Coreopsis: Seed Starting, Stratification, Spacing and Care for Tickseed

Coreopsis is a daisy-family genus; NC State says the name comes from Greek words for "bug" and "like," for the tick-shaped seed, which is also where "tickseed" comes from. Garden coreopsis come in a few types. Lance-leaf coreopsis (C. lanceolata) and large-flowered tickseed (C. grandiflora) are yellow, clumping plants 1 to 3 feet tall that bloom in spring and summer (NC State). Threadleaf coreopsis (C. verticillata) has fine, thread-like leaves and spreads by rhizomes (NC State). Plains coreopsis (C. tinctoria) is an annual, sometimes sold as calliopsis, with yellow flowers marked red (Wildflower Center). UF/IFAS notes coreopsis is Florida's state wildflower.

When to plant coreopsis

Use our planting calendar to count back 6 to 8 weeks from your last frost. The sources disagree on cold treatment, and our reading is that it depends on the species. Prairie Moon codes lance-leaf coreopsis seed C(30), its shorthand for 30 days of cold, moist stratification. NC State and the Wildflower Center say threadleaf and plains coreopsis seed needs no cold treatment, and the Wildflower Center says the genus generally germinates without pretreatment. So sow lance-leaf seed in late fall or winter, or chill it in damp media in the fridge for a month before spring sowing, and sow annual plains coreopsis whenever it suits you.

How to plant coreopsis

Indoors, keep seed warm, about 70°F (Almanac), moist and in bright light, then harden seedlings off for 7 to 10 days before planting out (Outsidepride).

Watering, feeding and deadheading

• Water to establish, then ease off. Clemson waters deeply through the first year, after which coreopsis is very drought tolerant. Outsidepride says bloom is heavier with steady watering.
• Go easy on fertilizer. Clemson says not to over-fertilize and to top-dress with compost; the Almanac warns that feeding makes plants spindly with few flowers.
• Deadhead to extend bloom and limit self-seeding (NC State, Wildflower Center). On big plantings, shear instead.
• Shear in midsummer. The Almanac cuts back a quarter to a half when flowers fade, Outsidepride a third, and NC State says shearing threadleaf coreopsis after bloom sometimes brings fall flowers.
• Divide every 2 to 3 years (NC State) or 3 to 4 years (Almanac) to keep clumps vigorous.

Coreopsis in containers

Clemson describes dwarf mouse-ear tickseed (C. auriculata 'Nana') as reaching only about 9 inches tall, and the Almanac lists compact cultivars such as threadleaf 'Zagreb' at 12 to 18 inches. Those sizes suit a large pot. Use a free-draining mix, since NC State warns that mouse-ear tickseed can get crown rot in wet soil (GardenPal reasoning).

Fall and winter

• Cut back after frost. After a couple of fall frosts the Almanac cuts perennials to 6 to 8 inches and clears debris, or leaves seed heads for birds.
• Leave some seed. Clemson says songbirds eat the seeds, and the Wildflower Center says annual plains coreopsis must be allowed to drop ripe seed for next year's display.
• Mulch around, not on, the crown (Almanac).

Pests and problems

Coreopsis has few problems: NC State lists no significant pests or diseases for lance-leaf, threadleaf or large-flowered types. The Almanac lists aphids, slugs and snails, and diseases such as aster yellows, botrytis, leaf spot, rust and powdery mildew, mostly in wet or crowded plantings. NC State says lance-leaf coreopsis can get weedy and resists deer, drought, heat and humidity; Clemson calls lance-leaf coreopsis an aggressive self-seeder and says native tickseeds are mildly tolerant of deer and rabbits. Flopping is the most common complaint, and NC State and the Almanac trace it to soil that is too rich or too wet.

Coreopsis around the vegetable garden

Coreopsis is one of the daisy-family flowers we list in flowers that attract beneficial insects for lady beetles and other larger predators, and Clemson calls it a fantastic pollinator plant that gives nectar through the season. Because it likes lean, dry soil, our reading is to plant it along the sunny, unwatered edge of the plot rather than in rich, irrigated vegetable beds. Good neighbors include black-eyed Susans, coneflowers, salvia and cosmos. For a summer border partner, see when to plant phlox. Yarrow likes the same lean, dry edge; see when to plant yarrow.

Frequently asked questions

When should I plant coreopsis?

Perennial plants any time from spring through early fall (Almanac). Sow seed outdoors after the last frost, or start it indoors 6 to 8 weeks before.

Should I cover coreopsis seeds?

No. Press them onto the soil, because light helps them germinate (Outsidepride, Almanac, Wildflower Center). UF/IFAS says no deeper than 1/8 inch.

Do coreopsis seeds need cold stratification?

It depends on the species. Prairie Moon codes lance-leaf coreopsis C(30), 30 days of cold, moist stratification, while NC State and the Wildflower Center say threadleaf and plains coreopsis need no cold treatment.

How far apart should I plant coreopsis?

12 to 18 inches (Almanac). Outsidepride thins to 12 inches and Prairie Moon spaces 10 to 16 inches.

Does coreopsis come back every year?

Most are perennials, but lance-leaf coreopsis is not reliably long-lived and carries on by reseeding (Wildflower Center). Plains coreopsis is an annual (NC State).

Why is my coreopsis flopping over?

Usually the soil is too rich or too moist (NC State). Skip fertilizer, and shear plants back by a third to a half in midsummer (Outsidepride, Almanac).