Growing Cleome (Spider Flower) from Seed: Indoor and Outdoor Methods

Overview

Cleome (spider flower) is a tall, stately annual with delicate pink, white, or lavender blossoms. Start indoors early spring or direct‑sow later for summer color. Self‑sows in fall, returning next spring.

Indoor Start (4–6 Weeks Before Last Frost)

1. Stratify: Mix seeds with ½ cup moist peat in sealed bag; refrigerate 1 week.
2. Sow: Surface‑sow in seed‑start mix, 2 in. apart. Light dusting of soil. Mist.
3. Germinate: Warm (85°F day / 65°F night). Mist daily. Light after emergence.
4. Pot up: At 4 true leaves, move to individual containers.
5. Harden & transplant: After 4 weeks indoors, plant 12 in. apart in compost‑amended bed. Water well.

Outdoor Direct Sow

1. Stratify as above.
2. Work soil 5 in. deep when 70°F+. Add 1–2 in. compost.
3. Sow 12 in. apart, light cover. Keep moist.
4. Pinch seedling bottom leaves for strength. Even moisture.
5. Water weekly if <1 in. rain. Mid‑season fertilize per label.
6. Mid‑summer blooms. Leave spent flowers for self‑sow; remove some/all to control volunteers.