When to plant rosemary in zone 5b — planting calendar

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Showing USDA Zone 5B

Growing SeasonZone 5b

Last frost ~May 15First frost ~Sep 30Today

Start indoorsTransplant / sowHarvestFrost risk

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Start indoors Mar 6 · Transplant May 15 · First harvest Aug 3 · Wrap by Sep 23

Last spring frostMay 15

Start seeds indoorsMar 6

Transplant outMay 15

First harvestAug 3

Last harvestSep 23

First fall frostSep 30

Why these dates work in zone 5b

Zone 5b's last spring frost averages May 15 and first fall frost Sep 30 — about 138 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 5b?

Rosemary matures in about 80–100 days from transplanting. In zone 5b that means setting plants out around May 15 and first picking around Aug 3.

Will rosemary survive frost in zone 5b?

No — rosemary is frost-sensitive. In zone 5b, wait until after the last frost (around May 15) to plant, and harvest before the first fall frost (around Sep 30).

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