Spider Flower

Cleome spinosa, known as spiny spiderflower or paradisblomster, is a fast-growing annual from South America bearing large, airy flower clusters in white, pink, rose, or violet. Plants reach 80–150 cm tall and carry sticky, hairy stems with distinctive spined foliage. It thrives in well-drained, nutrient-rich soil in a sunny, open position and is a magnet for pollinators. Because seeds ripen readily, it can self-seed prolifically if seed pods are left on the plant.

Growing

Sow seeds shallowly — no more than 0.2 cm deep — indoors under light (seeds are light-dependent germinators). For improved germination rates, stratify seeds in the refrigerator for 3–6 weeks before sowing, then move to a warm location with day temperatures around 25 °C and night temperatures around 15 °C. Start seedlings approximately 10 weeks before outdoor transplanting. Harden off gradually and plant out only once nights reliably stay above 8 °C and all frost risk has passed. Space plants 30–50 cm apart in rows 100–150 cm wide.

Care

Water regularly but avoid waterlogging; well-drained soil is essential. Feed with a balanced fertiliser every 2–3 weeks once established. Tall plants almost always require staking — insert supports early before stems become difficult to tie. Deadhead spent flowers to extend the blooming period, or leave seed pods to mature if you wish to collect seeds for the following year.

Harvest

Cut flower stems once the lower florets on each raceme have opened fully and the upper buds are still in colour. Harvest in the early morning for the longest vase life. Plants flower continuously from midsummer until the first frost, providing a long cutting window of approximately 60 days. If seed collection is the goal, allow pods to turn beige and feel dry before gathering; store in a paper envelope in a cool, dry place.

In the kitchen

Cleome spinosa is grown primarily as an ornamental and cut flower. The fresh blooms are striking in mixed bouquets and floral arrangements, where the spidery stamens add dramatic texture. Young leaves and flowers are edible and have been used as a cooked green in parts of the Americas, with a pungent, mustardy flavour.

Storing

Cut stems last 5–7 days in fresh water in a cool room. Re-cut stems at an angle daily and change the water to maximise vase life. Dried seed heads can be used in dried floral arrangements; hang stems upside down in a warm, airy space until fully desiccated.