When to plant thyme in zone 3b — planting calendar

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Showing USDA Zone 3B

Growing SeasonZone 3b

Last frost ~May 25First frost ~Sep 15Today

Start indoorsTransplant / sowHarvestFrost risk

MARAPRMAYJUNJULAUGSEP

Start indoors Mar 30 · Transplant May 18 · First harvest Jul 17 · Wrap by Sep 15

Last spring frostMay 25

Start seeds indoorsMar 30

Transplant outMay 18

First harvestJul 17

Last harvestSep 15

First fall frostSep 15

Why these dates work in zone 3b

Zone 3b's last spring frost averages May 25 and first fall frost Sep 15 — about 113 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 3b?

Thyme matures in about 60–90 days from transplanting. In zone 3b that means setting plants out around May 18 and first picking around Jul 17.

Will thyme survive frost in zone 3b?

Yes — thyme tolerates light frost. In zone 3b you can set plants out a little before the last frost (around May 25) and keep harvesting past the first fall frost (around Sep 15).

For soil, spacing, pests and companion planting, see the full thyme growing guide →