How to grow coreopsis
Overview
Coreopsis grandiflora is a herbaceous perennial grown for its bright yellow, daisy-like flowers and fine, ferny foliage. It thrives in full sun and well-drained soil, providing long-lasting colour in garden beds.
Varieties
- Coreopsis grandiflora 'Early Sunrise' — Compact, early-flowering variety with semi-double blooms, ideal for pots.
- Coreopsis grandiflora 'Sunburst' — Large, golden-yellow flowers on tall stems, excellent for cutting.
Soil Preparation
Coreopsis prefers a slightly acidic to neutral pH (6.0-7.0) and well-drained soil. Amend heavy clay with organic matter or sand to improve drainage. Avoid waterlogged sites.
Growing Guide
Sow seeds directly in spring after frost, or start indoors 6 weeks before last frost. Space plants 30-45 cm apart in full sun and well-drained soil. For best flowering, plant in a position that receives at least 6 hours of direct sun daily. Deadhead spent blooms regularly to extend the flowering season.
Sowing
Sow seeds 3 mm deep, 30 cm apart. Germination takes 7-14 days at 18-24°C. Direct sow after frost or start indoors for earlier blooms.
Care
Feed with a balanced slow-release fertiliser in early spring and after the first flush of flowers. Cut back spent stems to the base in late autumn to encourage fresh growth. Divide clumps every 2-3 years to maintain vigour.
Companion Planting
Coreopsis pairs well with Echinacea, Gaillardia, and Salvia. Avoid planting near heavy feeders like tomatoes that may compete for nutrients.
Common Pests & Risks
Aphids may cluster on new growth; spray with a strong jet of water or insecticidal soap. Powdery mildew appears in humid conditions; improve air circulation and avoid overhead watering.
Harvesting
Cut flowers when fully open, in the morning after dew has dried. Use immediately in fresh arrangements; stems last 5-7 days in water. Regular harvesting encourages more blooms.
Troubleshooting
Yellow leaves: overwatering or poor drainage; reduce water and improve soil. Stunted growth: lack of sun; move to full sun. Powdery mildew: high humidity; space plants and avoid overhead watering. Few flowers: over-fertilising with nitrogen; use a balanced feed. Leggy stems: too much shade; pinch back and move to sun.