Cleome hassleriana

Sowing and care guidance

Sow Cleome hassleriana seeds in full sun and well-drained, moderately fertile soil. Start indoors shortly before the last frost, transplanting only after frost has passed, or direct sow once the soil is warm; in mild climates, autumn sowing can give an earlier bloom. As a tall annual, allow generous spacing for airflow and sturdy growth, thinning rather than crowding. Keep evenly moist during establishment, then water deeply but infrequently to encourage resilience. Avoid over‑rich feeding, which promotes leafy growth at the expense of flowers. Pinch lightly when young to encourage branching, and remove spent blooms to prolong display.

• Start under cover shortly before the last frost; transplant after frost. Or direct sow when soil is warm; in mild climates, autumn sowing may advance flowering.
• Allow generous spacing for airflow; avoid crowding. As a tall annual, provide support in exposed, windy sites.
• Grow in full sun and well-drained, moderately fertile soil; avoid high-nitrogen feeding.
• Flowers are attractive to pollinators.
• Ornamental value: airy, long-lasting flower clusters and architectural height.

How do you grow Cleome hassleriana from seed?

Sow Cleome hassleriana seeds shortly before the last frost if starting indoors, or outdoors once the soil is warm and frost has passed. Use a free-draining seed mix, sow on the surface and lightly cover 2–3 mm or press in for light contact. Keep at 20–24°C and evenly moist; germination usually takes 7–21 days. Harden off gradually before planting out. Provide full sun and well-drained, moderately fertile soil. Avoid high-nitrogen feeding, which can encourage lanky growth at the expense of flowers.

When should I sow spider flower seeds in relation to frost?

Start indoors shortly before the last frost, then transplant only after all frost risk has passed and nights are mild. For direct sowing, wait until the soil is warm and workable and daytime warmth is reliable. In mild climates, autumn sowing can be successful for earlier flowering the following season if young plants are given protection from cold snaps. In all cases, warmth and good light are key to steady establishment and timely blooms.

What spacing and care does Cleome hassleriana need?

Allow generous spacing for airflow, typically 45–60 cm between plants, as this tall annual can reach about 90–150 cm in height. Grow in full sun and well-drained, moderately fertile soil; overly rich conditions promote excess leaf growth. Water to establish, then allow the topsoil to dry slightly between waterings. Stake in exposed, windy sites. Deadhead to keep plants tidy, or leave some seedheads to mature if self-seeding is desired. Light pinching of young plants can encourage bushier growth.

Does cleome attract pollinators?

Yes. Spider flower’s open, nectar-rich blooms and prominent stamens are attractive to a wide range of pollinators, including bees, butterflies, and other long-tongued visitors. Planting Cleome hassleriana seeds in a sunny, undisturbed spot helps create a steady nectar source through the warm months. Avoid excessive pesticide use nearby, and stagger sowings or allow some self-seeding to extend the flowering window for foraging insects.

Can cleome grow in containers?

Cleome can be grown in containers if you choose a large, stable pot with ample depth to accommodate its taproot—around 30–40 cm diameter per plant, larger for groupings. Use a well-drained, peat-free potting mix and ensure full sun. Water consistently but avoid waterlogging, and consider a discreet stake as plants gain height. Container-grown plants benefit from a light, balanced feed during active growth; avoid high-nitrogen products to maintain sturdy, floriferous growth.

Is it better to direct sow cleome or transplant seedlings?

Both approaches work. Direct sowing into warm soil is simple and avoids disturbing the taproot, often yielding robust plants that establish where they will flower. Transplanting can bring earlier blooms if seeds are started indoors, but seedlings should be moved while small and handled gently, ideally in biodegradable pots to reduce root disturbance. Whichever method you choose, maintain generous spacing and full sun for the best display.

This site provides general growing guidance compiled from supplier information and widely used horticultural references. Actual results can vary with microclimate, soil structure and fertility, drainage, and seasonal timing (for example, after last frost or when soil is workable). For precise sowing depth, spacing, and timing, consult each product page; it contains variety-specific instructions derived from the source material and aligned with our quality and compliance standards.

Cultivation notes for spider flower

Cleome hassleriana seeds offer airy, long-stamened blooms that rise above palmate foliage, adding height and movement to seasonal displays. Start under cover while frost risk remains, or direct sow after the last frost when soil is workable and warm. Lightly press seed onto the surface, as exposure to light supports germination; steady warmth and even moisture help emergence. In mild climates, autumn sowing may be possible for earlier flowering the following warm season. Grow in full sun and well-drained, moderately fertile soil. Space plants 30–45 cm apart for airflow; tall growth may benefit from discreet staking in windy sites. Water to establish, then allow the top layer of soil to dry slightly between waterings. Deadhead for a neat appearance; to limit self-seeding, remove spent blooms before pods mature. Expect flowering through sustained warm weather until frost returns. Reference: SeedsChoice.