Last spring frostMay 6
Direct sowMay 20
First harvestJul 29
Last harvestAug 19
First fall frostOct 22
Why these dates work in zone 3b
Zone 3b's last spring frost averages May 6 and first fall frost Oct 22 — about 169 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 3b?
Corn matures in about 70–90 days from sowing. In zone 3b that means sowing around May 20 and first picking around Jul 29.
Will corn survive frost in zone 3b?
No — corn is frost-sensitive. In zone 3b, wait until after the last frost (around May 6) to plant, and harvest before the first fall frost (around Oct 22).
For soil, spacing, pests and companion planting, see the full corn growing guide →