Last spring frostMay 6
Start seeds indoorsMar 11
Transplant outMay 6
First harvestJul 5
Last harvestOct 22
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. Mint tolerates light frost, so you can set plants out ahead of the last-frost date and keep harvesting into the cooler fall. Starting seeds indoors 8 weeks ahead gives strong transplants ready the moment the soil warms.
Common questions
How long does mint take to grow in zone 3b?
Mint matures in about 60–90 days from transplanting. In zone 3b that means setting plants out around May 6 and first picking around Jul 5.
Will mint survive frost in zone 3b?
Yes — mint tolerates light frost. In zone 3b you can set plants out a little before the last frost (around May 6) and keep harvesting past the first fall frost (around Oct 22).
For soil, spacing, pests and companion planting, see the full mint growing guide →