Cleome (Spider Flower) in Zone 4a & 4b
Cleome hassleriana
When to plant cleome (spider flower) in zone 4b
Zones 4a and 4b 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 | Mar 27–Apr 3 |
|---|---|
| Direct sow / transplant outside | May 29–Jun 5 |
| Estimated bloom | Aug 12–Aug 19 (~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 4's season
Zone 4b's frost-free window runs about 128 days, from May 15 to September 20. 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 →
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See it growing
Search YouTube for "growing cleome (spider flower)" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 4b calendar · Full companion planting guide · Full plant profile · Plan your beds in the Garden Designer →

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Growing Cleome (Spider Flower) in USDA zone 4b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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