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 once the soil is warm and nights stay mild. Plant in blocks of several short rows, not one long row, for good pollination. Water well while the tassels and silks form.
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.