How to grow cleome
Overview
Cleome hassleriana, commonly known as spider flower, is a tall, fast-growing annual grown for its showy clusters of pink, white, or purple flowers and distinctive palm-shaped leaves. It thrives in heat and full sun, making it an excellent gap-filler in summer borders.
Varieties
- Cleome 'Senorita Rosalita' — A sterile, non-seeding hybrid with soft pink flowers and long bloom season, popular in Australian gardens.
- Cleome 'Sparkler Blush' — Compact variety with bicolour pink and white flowers, ideal for smaller spaces.
- Cleome 'Queen' series — Tall mix in pink, rose, and white; vigorous and heat-tolerant.
Soil Preparation
Cleome prefers slightly acidic to neutral soil (pH 6.0–7.0) with good drainage. Enrich with compost or well-rotted manure before planting. Avoid heavy clay; if soil is poor, add a handful of slow-release fertiliser at planting.
Growing Guide
Sow seeds directly 5mm deep in warm soil after frost risk passes, spacing 30–45cm apart. Cleome prefers rich, well-drained soil and consistent moisture; avoid waterlogging. Pinch out tips when 15cm tall to encourage branching. Stake tall stems in exposed gardens. Deadhead regularly to extend bloom into autumn.
Sowing
Sow seeds 5mm deep, 30cm apart, in full sun after soil warms. Germinates in 7–14 days at 20–25°C. Direct sow is preferred; transplant only if starting in pots, taking care not to disturb roots. Soak seeds overnight to improve germination.
Care
Feed every 2–3 weeks with a balanced liquid fertiliser (e.g., 10-10-10) during active growth. Cut back leggy stems by one-third after the first bloom flush to promote bushiness. Remove spent flower heads to prevent self-seeding if desired.
Companion Planting
Cleome attracts bees, butterflies, and beneficial hoverflies. Plant near zinnias, cosmos, or salvias for a pollinator-friendly bed. Avoid planting near heavy feeders like corn that may compete for nutrients.
Common Pests & Risks
Aphids cluster on new growth in spring; spray with pyrethrum or neem oil. Spider mites appear in dry heat; hose off foliage or apply horticultural oil. Whitefly may also occur; use yellow sticky traps.
Harvesting
Harvest flower stems when the lowest 2–3 blooms are open, cutting at the base. Remove lower leaves and place in water immediately. Flowers last 5–7 days in a vase. For seed saving, let pods dry on the plant.
Troubleshooting
Yellow lower leaves: overwatering or poor drainage; reduce water. Stunted growth: cold soil or late planting; wait for warmth. Leggy stems: insufficient light; move to full sun. Powdery mildew: poor air circulation; space plants wider. Flowers drop early: heat stress; mulch to keep roots cool.