When to plant Basil in Zone 4a
In Zone 4a, Basil: start seeds indoors around Apr 3–Apr 17; transplant outdoors around May 22–Jun 5. Expect to harvest around Jul 21–Aug 4.
| Step | When |
|---|---|
| Start seeds indoors | Apr 3 – Apr 17 |
| Transplant outdoors | May 22 – Jun 5 |
| Harvest | Jul 21 – Aug 4 |
Tip: Extremely frost-sensitive. Keep indoors until nights are reliably warm, then pinch often.
Zone 4a averages a last spring frost around May 15 and a first fall frost around Sep 18. These are zone averages — look up your ZIP for your exact area.
See the full Zone 4a calendar in the tool →