When to plant Onion in Zone 1a
In Zone 1a, Onion: start seeds indoors around Apr 6–Apr 20; transplant outdoors around May 18–Jun 1. Expect to harvest around Aug 26–Sep 9.
| Step | When |
|---|---|
| Start seeds indoors | Apr 6 – Apr 20 |
| Transplant outdoors | May 18 – Jun 1 |
| Harvest | Aug 26 – Sep 9 |
Tip: Day-length sensitive — match the variety (long/short day) to your latitude for big bulbs.
Zone 1a averages a last spring frost around Jun 15 and a first fall frost around Aug 15. These are zone averages — look up your ZIP for your exact area.
See the full Zone 1a calendar in the tool →