Cleome (Spider Flower) in Zone 9a & 9b

Cleome hassleriana

When to plant cleome (spider flower) in zone 9b

Zones 9a and 9b share the same average frost dates in our data, so this page covers both.

Method: Either: Start indoors for an earlier harvest, or direct-sow outside for less fuss. Cleome (Spider Flower) tolerates either.

Start indoors	Dec 28–Jan 4 '27
Direct sow / transplant outside	Mar 1–Mar 8
Estimated bloom	May 15–May 22 (~75 days after planting)

Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 1.5-6 ft.

Cleome, also called spider flower, is one of the taller plants on this site, anywhere from 1.5 to 6 feet depending on the cultivar, and it earns that height by being a serious draw for hummingbirds, bees, butterflies, and predatory insects that help keep pest populations down elsewhere in the garden. The classic species form does have a downside worth knowing up front: sticky sap, a noticeable odor, and stems armed with small spines.

How cleome (spider flower) fits zone 9's season

Zone 9b's frost-free window runs about 293 days, from February 15 to December 5. Cleome (Spider Flower) needs about 75 days from sowing to first harvest.

Good companions

No standout companions recorded yet for Cleome (Spider Flower).

Where to buy cleome seeds

See why we recommend these suppliers →

As an Amazon Associate we earn from qualifying purchases. Some links on this page also go to other retailers we may earn a commission from as an affiliate, at no extra cost to you. We only recommend products with a genuine consensus of positive, independent reviews. See the sources cited on each item.