Cleome (Spider Flower) in Zone 10a & 10b
Cleome hassleriana
Yes, cleome (spider flower) grows in zones 10a and 10b. Start seeds indoors Dec 12–Dec 19 and plant out Feb 13–Feb 20.
When to plant cleome (spider flower) in zone 10b
Zones 10a and 10b share the same average frost dates, so this page covers both.
Method: Either: Start indoors for an earlier harvest, or direct-sow outside for less fuss. Either works.
| Start indoors | Dec 12–Dec 19 |
|---|---|
| Direct sow / transplant outside | Feb 13–Feb 20 |
| Estimated bloom | Apr 29–May 6 (~75 days after planting) |
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 1.5-6 ft.
Plant alongside it in zone 10b
These go outside within two weeks of cleome (spider flower) in zone 10b, so one planting day can cover them.
- MarigoldFeb–May
- Black-Eyed Susan VineFeb 13–Feb 20
- ColeusFeb 13–Feb 20
- ImpatiensFeb 13–Feb 20
- LantanaFeb 13–Feb 20
- Morning GloryFeb 13–Feb 20
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 10's season
Zone 10b's frost-free window runs about 324 days, from January 30 to December 20. Cleome (spider flower) needs about 75 days from sowing to first bloom.
Cleome (Spider Flower) planting windows in every zone
Zone 10b is highlighted. Useful for comparing against a neighbouring zone, or for a garden somewhere else.
| Zone | Start indoors | Sow or plant out | Bloom |
|---|---|---|---|
| 2a & 2b | Apr 1–Apr 8 | Jun 3–Jun 10 | Aug 17–Aug 24 |
| 3a & 3b | Apr 11–Apr 18 | Jun 13–Jun 20 | Aug 27–Sep 3 |
| 4a & 4b | Mar 27–Apr 3 | May 29–Jun 5 | Aug 12–Aug 19 |
| 5a & 5b | Mar 22–Mar 29 | May 24–May 31 | Aug 7–Aug 14 |
| 6a & 6b | Mar 7–Mar 14 | May 9–May 16 | Jul 23–Jul 30 |
| 7a & 7b | Feb 20–Feb 27 | Apr 24–May 1 | Jul 8–Jul 15 |
| 8a & 8b | Feb 4–Feb 11 | Apr 8–Apr 15 | Jun 22–Jun 29 |
| 9a & 9b | Dec 28–Jan 4 | Mar 1–Mar 8 | May 15–May 22 |
| 10a & 10b (your zone) | Dec 12–Dec 19 | Feb 13–Feb 20 | Apr 29–May 6 |
| 11a & 11b | Nov 13–Nov 20 | Jan 15–Jan 22 | Mar 31–Apr 7 |
Bloom dates are about 75 days after the sow or plant-out date, not after starting seeds indoors.
Zone 2 sows before zone 3 here, which looks wrong and is not. USDA zones rank winter cold, not season length, and zone 2 is mostly interior Alaska, where hard winters come with warm summers. More on what a zone measures.
Good companions
No well-established companions for cleome (spider flower).
Where to buy cleome seeds
True Leaf Market · Burpee · High Mowing Organic Seeds (each supplier's 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 10b calendar · Plan your beds in the Garden Designer →
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Growing Cleome (Spider Flower) in USDA zone 10b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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