Last spring frostMay 6
Transplant outMay 27
First harvestAug 25
Last harvestSep 15
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. Sweet Potato is frost-sensitive, so the 3w 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 sweet potato take to grow in zone 3b?
Sweet Potato matures in about 90–120 days from transplanting. In zone 3b that means setting plants out around May 27 and first picking around Aug 25.
Will sweet potato survive frost in zone 3b?
No — sweet potato 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 sweet potato growing guide →