When to plant rosemary in zone 3a — planting calendar

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Showing USDA Zone 3A

Growing SeasonZone 3a

Last frost ~May 30First frost ~Sep 10Today

Start indoorsTransplant / sowHarvestFrost risk

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Start indoors Mar 21 · Transplant May 30 · First harvest Aug 18 · Wrap by Sep 3

Last spring frostMay 30

Start seeds indoorsMar 21

Transplant outMay 30

First harvestAug 18

Last harvestSep 3

First fall frostSep 10

Why these dates work in zone 3a

Zone 3a's last spring frost averages May 30 and first fall frost Sep 10 — about 103 frost-free days. Rosemary is frost-sensitive, so the around last frost timing builds in a safety margin against a late cold snap — setting plants out too early risks losing them to frost. Starting seeds indoors 10 weeks ahead gives strong transplants ready the moment the soil warms.

Common questions

How long does rosemary take to grow in zone 3a?

Rosemary matures in about 80–100 days from transplanting. In zone 3a that means setting plants out around May 30 and first picking around Aug 18.

Will rosemary survive frost in zone 3a?

No — rosemary is frost-sensitive. In zone 3a, wait until after the last frost (around May 30) to plant, and harvest before the first fall frost (around Sep 10).

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