Threadleaf coreopsis

Sun

Full sun, ideally at least 6 hours daily; light shade is tolerated but usually reduces flowering.

Water

Water regularly during the first growing season. Once established, water during prolonged dry spells rather than keeping the soil constantly moist.

Soil

Well-drained sandy, gravelly or loamy soil; tolerates relatively poor soil. Avoid waterlogged ground, especially in winter.

Height

2-3 ft (0.6-0.9 m)

Spread

1.5-2 ft (0.45-0.6 m), gradually widening through short rhizomes

Flowers

Yellow flowers from early summer into early autumn, with repeat flowering encouraged by trimming.

Foliage

Fine, threadlike green leaf segments give the plant a soft, airy appearance. Top growth dies back in winter.

Growth

Moderate; forms a flowering clump within one or two growing seasons.

Care needed

Low

• Water new plants deeply when the root zone begins to dry; avoid frequent shallow watering.
• Skip routine feeding in ordinary garden soil; rich soil and excess fertiliser encourage floppy growth.
• Keep mulch away from the crown and avoid thick, moisture-holding mulch on heavy soil.
• Divide congested clumps in spring, usually every three to four years.
• Grow in full sun to reduce flopping; use discreet supports only if stems lean into paths.

Pruning. After the main flush fades, shear off spent flower stems and up to one-third of the leafy growth to encourage another flush. Leave healthy stems over winter if wanted for wildlife, then cut them close to ground level in late winter or early spring before new growth develops.

Early spring

Cut down remaining dead stems before new shoots lengthen.

Spring

Plant or divide clumps in well-drained soil, allowing room for gradual spread.

Late spring

Check new plants for dry soil and water deeply when needed.

Summer

Trim faded flower stems after the main flush to encourage repeat flowering.

Late summer

Remove unwanted shoots at the clump's edges and water during prolonged drought.

Autumn

Leave some seedheads for birds and keep fallen leaves from forming a wet mat over the crown.

• Plant in repeated groups through a sunny perennial border for a long-running band of yellow.
• Combine with purple salvia or catmint for contrasting flower colours and foliage textures.
• Use beside ornamental grasses in informal, meadow-style planting, where its fine leaves blend with narrow grass blades.
• Plant in a sunny gravel garden with other drought-tolerant perennials, keeping the crown free of wet organic mulch.

Garden styles it suits: Cottage garden, New perennial (prairie), Pollinator garden, Low-maintenance, Dry gravel garden and Native meadow.

Plant it with: Purple coneflower, Meadow sage, Catmint, Yarrow, Little bluestem and Butterfly weed.

Wildlife: Flowers provide pollen and nectar for bees and other insects. Seedheads can feed small seed-eating birds if left standing.

• Crown or root rot in wet soil: improve drainage or move the plant to a raised position; discard badly rotted plants.
• Powdery mildew: allow more space and airflow, avoid drought stress, and remove affected debris at the end of the season.
• Slugs and snails damaging young shoots: inspect emerging growth and use hand-picking or locally approved iron phosphate bait.
• Floppy stems or weak flowering: move to fuller sun, stop feeding and avoid excessive watering.

Not known to be toxic to cats, dogs, horses or people; no plant parts are recognised as poisonous. It is not a food plant, and eating substantial amounts may cause digestive upset.

• Large-flowered tickseed (Coreopsis grandiflora)

  Usually has larger yellow flowers and much broader leaves or leaf lobes, rather than the consistently fine, threadlike foliage of threadleaf coreopsis.

• Lanceleaf tickseed (Coreopsis lanceolata)

  Has broad, lance-shaped leaves concentrated near the base and flowers carried on relatively bare stems.

• Plains coreopsis (Coreopsis tinctoria)

  Usually an annual, with yellow flowers commonly marked by a conspicuous dark red-brown ring around the centre; its upper foliage can also look finely divided.

Coreopsis comes from Greek words meaning bug-like, referring to the seeds' appearance, while verticillata means whorled and refers to the leaf arrangement.

Propagation. Divide clumps in spring, keeping roots and growing shoots on each section. The species can also be grown from seed sown in spring; seedlings from named cultivars may not match the parent, so divide cultivars to keep their characteristics.

Accepted botanical name

Coreopsis verticillata

In the US and Canada

Native in the lower 48 states. Introduced in Canada.

Sources: GBIF (CC BY 4.0) and USDA PLANTS. The care and design notes are LandscapeGPT's own.