Last spring frostMay 7
Start seeds indoorsMar 12
Transplant outApr 30
First harvestJun 29
Last harvestOct 13
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. Thyme 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 thyme take to grow in zone 4a?
Thyme matures in about 60–90 days from transplanting. In zone 4a that means setting plants out around Apr 30 and first picking around Jun 29.
Will thyme survive frost in zone 4a?
Yes — thyme tolerates light frost. In zone 4a you can set plants out a little before the last frost (around May 7) and keep harvesting past the first fall frost (around Oct 13).
For soil, spacing, pests and companion planting, see the full thyme growing guide →