When to plant corn in zone 4b — planting calendar

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Showing USDA Zone 4B

Growing SeasonZone 4b

Last frost ~May 15First frost ~Sep 25Today

Start indoorsTransplant / sowHarvestFrost risk

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Sow May 29 · First harvest Aug 7 · Wrap by Aug 28

Last spring frostMay 15

Direct sowMay 29

First harvestAug 7

Last harvestAug 28

First fall frostSep 25

Why these dates work in zone 4b

Zone 4b's last spring frost averages May 15 and first fall frost Sep 25 — about 133 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 4b?

Corn matures in about 70–90 days from sowing. In zone 4b that means sowing around May 29 and first picking around Aug 7.

Will corn survive frost in zone 4b?

No — corn is frost-sensitive. In zone 4b, wait until after the last frost (around May 15) to plant, and harvest before the first fall frost (around Sep 25).

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