Zone 4b covers 52 days of last-frost dates. We measured Pierre, SD at Apr 28 and Jackson, WY at Jun 19. Give us your town or ZIP and we'll use ten years of daily lows recorded at your own coordinates instead of the middle of that range.
Why these dates work in zone 4b
Zone 4b's last spring frost averages May 4 and first fall frost Oct 20 — about 169 frost-free days. Potato tolerates light frost, so you can sow ahead of the last-frost date and keep harvesting into the cooler fall.
Common questions
How long does potato take to grow in zone 4b?
Potato matures in about 70–120 days from sowing. In zone 4b that means sowing around Apr 20 and first picking around Jun 29.
Will potato survive frost in zone 4b?
Yes — potato tolerates light frost. In zone 4b you can sow a little before the last frost (around May 4) and keep harvesting past the first fall frost (around Oct 20).
For soil, spacing, pests and companion planting, see the full potato growing guide →