Last spring frostMay 7
Direct sowMay 21
First harvestJul 30
Last harvestAug 20
First fall frostOct 13
Why these dates work in zone 4a
Zone 4a's last spring frost averages May 7 and first fall frost Oct 13 — about 159 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 May 21 and first picking around Jul 30.
Will corn survive frost in zone 4a?
No — corn is frost-sensitive. In zone 4a, wait until after the last frost (around May 7) to plant, and harvest before the first fall frost (around Oct 13).
For soil, spacing, pests and companion planting, see the full corn growing guide →