When to plant thyme in zone 4a — planting calendar

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Showing USDA Zone 4A

Growing SeasonZone 4a

Last frost ~May 20First frost ~Sep 20Today

Start indoorsTransplant / sowHarvestFrost risk

MARAPRMAYJUNJULAUGSEP

Start indoors Mar 25 · Transplant May 13 · First harvest Jul 12 · Wrap by Sep 20

Last spring frostMay 20

Start seeds indoorsMar 25

Transplant outMay 13

First harvestJul 12

Last harvestSep 20

First fall frostSep 20

Why these dates work in zone 4a

Zone 4a's last spring frost averages May 20 and first fall frost Sep 20 — about 123 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 May 13 and first picking around Jul 12.

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 20) and keep harvesting past the first fall frost (around Sep 20).

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