Sweet Corn in Zone 10a & 10b
Zea mays
When to plant sweet corn in zone 10b
Zones 10a and 10b share the same average frost dates in our data, so this page covers both.
Method: Direct sow: Direct-sow outside. Sweet Corn doesn't transplant well, or doesn't need the extra time indoors.
| Window | Spring window |
|---|---|
| Start indoors | Not typically started indoors |
| Direct sow / transplant outside | Feb–Mar |
| Estimated harvest | Apr 17–Jun 14 (~75 days after direct-sowing) |
| Window | Monsoon window |
|---|---|
| Start indoors | Not typically started indoors |
| Direct sow / transplant outside | Jul–Aug |
| Estimated harvest | Sep 14–Nov 14 (~75 days after direct-sowing) |
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 5-8 ft.
Zone 10b dates sourced from growinginthegarden.com.
Corn takes up a full square foot per plant and grows tall enough to shade everything around it, so it's a bigger commitment than most vegetables, and unlike almost everything else in the garden, it needs company. A single row or a lonely handful of stalks is the most common way home gardeners end up with ears full of blank, unpollinated patches.
How sweet corn fits zone 10's season
Zone 10b's frost-free window runs about 324 days, from January 30 to December 20. Sweet Corn needs about 75 days from sowing to first harvest.
Good companions
- Bush Beans: The classic 'three sisters' pairing. WSU Extension confirms the real mechanism: beans climb corn stalks and fix nitrogen the corn uses.
- Winter Squash: The third 'three sisters' pairing. WSU Extension confirms squash's broad leaves shade the soil, reducing evaporation and suppressing weeds around corn.
Where to buy sweet corn seeds
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing sweet corn" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 10b calendar · Full companion planting guide · Full plant profile · Plan your beds in the Garden Designer →
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Growing Sweet Corn in USDA zone 10b: when to start seeds indoors, when to direct-sow, and when to expect a harvest.
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