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← How to grow rosemary
Planting Calendar · Zone 3A

When to plant rosemary in zone 3a

In USDA zone 3a, start rosemary seeds indoors around Mar 21, transplant outdoors May 30, and harvest from Aug 18.

We don’t publish a planting calendar for zone 3a, because every date on one would be counted from a last-frost date this zone doesn’t reliably have. Rosemary takes about 80–100 days from transplanting to first picking, and that part holds anywhere. For real dates, tell us where you are below and Garzed reads ten years of weather at your own coordinates.

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. One caveat: we haven't yet checked zone 3a against the weather archive, so those frost dates are an inherited estimate rather than a measurement. Give Garzed your location and it works from that location's own ten-year record instead.

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 →