DibbleWhen to plant corn in Zone 9
In Zone 9, the last spring frost usually passes around March 1 and the first fall frost arrives around December 1, leaving about 275 frost-free days. The windows below are computed from those frost dates, with the same math the Dibble app uses.
Very long season. Plant cool crops in fall and winter; manage summer heat.
Planting windows for corn in Zone 9
| Task | Window |
|---|---|
| Direct sow | Mar 8 to Mar 22 |
| Estimated harvest | May 22 to Jun 1 |
The harvest estimate counts 75 days to maturity, then a picking window of about 10 days. These windows use typical frost dates for Zone 9; Dibble pins them to your exact ZIP code.
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Sweet Corn in a Zone 9 season
Zone 9 gives about 275 frost-free days. Sweet Corn needs roughly 75 days from sowing. That leaves about 200 days of slack, so there is room for a late start or a second planting.
How to grow corn
Sow corn a week after last frost in warm soil. Plant in blocks of several short rows, not one long row, for good pollination.
Companion plants
Good neighbors for Sweet Corn:
Better kept apart:
Sweet Corn in other zones
Not in Zone 9? Pick your zone for the same dated windows.
Keep exploring
Sweet Corn: the full growing guide · The Zone 9 planting calendar · Every crop and zone
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Dates are estimates based on typical frost dates for the zone. Your yard has its own microclimate, so use them as a starting point and adjust as you learn your space.