Cleome hassleriana. Big clusters of light pink flowers with reddish highlights and very long stamens appear above erect stems with spirally arranged leaves. You might not even notice the plant until the first flowers open - like roman candles in the garden! The flowers are very exotic looking, with quite a unique structure. Plants from Spider Flower Cleome seeds grow as tall as 150cm (60"), but usually a bit shorter on the coast. Spider Flowers are attractive to hummingbirds and beneficial insects. This native of southern South America is too tall for most containers, but it sure looks good planted in small groups in the garden.
Cleome is very easy to grow once established, and may work best from direct-sown seeds. Any ordinary garden soil will work, including dry areas once plants are established. Cleome self-sows with gusto, so if you want to avoid this, remove flower heads before seeds ripen. This annual native of South America is quite drought tolerant so it's good for xeriscaping. Continue reading below for more tips on how to grow Cleome from seed.
Cleome hassleriana, C. serrulata, and many others
Season & Zone
Exposure: Full sun or very light shade
Start indoors from 6-8 weeks prior to the last frost date for transplanting (or simply direct sow) 3-4 weeks after last frost. If direct sowing, consider repeating every two weeks into early summer for a longer bloom period. Seeds will sprout in 10-14 days.
Sow on the surface of the soil. If starting indoors, seeds benefit from vernalization: Place seeds on the surface of moistened, sterilized seed starting mix in pots, and place pots in zip-top plastic bags inside the refrigerator for 2 weeks. Then move pots to bottom heat and maintain soil temperature at 21-25°C (70-75°F) until germination. Provide bright light.
Cleome is quite an undemanding annual. The stems are usually very strong and upright, but might benefit from support in very windy, exposed gardens.