When to plant Rosemary in Zone 3b
In Zone 3b, Rosemary: start seeds indoors around Mar 11–Mar 25; transplant outdoors around Jun 3–Jun 17. Expect to harvest around Sep 1–Sep 15.
| Step | When |
|---|---|
| Start seeds indoors | Mar 11 – Mar 25 |
| Transplant outdoors | Jun 3 – Jun 17 |
| Harvest | Sep 1 – Sep 15 |
Tip: Slow from seed and frost-tender in cold zones — most gardeners start from a plant and overwinter indoors.
Zone 3b averages a last spring frost around May 20 and a first fall frost around Sep 12. These are zone averages — look up your ZIP for your exact area.
See the full Zone 3b calendar in the tool →