When to plant corn in zone 4a — planting calendar

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Showing USDA Zone 4A

Growing SeasonZone 4a

Last frost ~May 20First frost ~Sep 20Today

Start indoorsTransplant / sowHarvestFrost risk

MAYJUNJULAUGSEP

Sow Jun 3 · First harvest Aug 12 · Wrap by Sep 2

Last spring frostMay 20

Direct sowJun 3

First harvestAug 12

Last harvestSep 2

First fall frostSep 20

Why these dates work in zone 4a

Zone 4a's last spring frost averages May 20 and first fall frost Sep 20 — about 123 frost-free days. Corn is frost-sensitive, so the 2w after frost timing builds in a safety margin against a late cold snap — setting plants out too early risks losing them to frost.

Common questions

How long does corn take to grow in zone 4a?

Corn matures in about 70–90 days from sowing. In zone 4a that means sowing around Jun 3 and first picking around Aug 12.

Will corn survive frost in zone 4a?

No — corn is frost-sensitive. In zone 4a, wait until after the last frost (around May 20) to plant, and harvest before the first fall frost (around Sep 20).

For soil, spacing, pests and companion planting, see the full corn growing guide →