When to plant Onion in Zone 10a
In Zone 10a, Onion: start seeds indoors around Nov 22–Dec 6; transplant outdoors around Jan 3–Jan 17. Expect to harvest around Apr 13–Apr 27.
| Step | When |
|---|---|
| Start seeds indoors | Nov 22 – Dec 6 |
| Transplant outdoors | Jan 3 – Jan 17 |
| Harvest | Apr 13 – Apr 27 |
Tip: Day-length sensitive — match the variety (long/short day) to your latitude for big bulbs.
Zone 10a averages a last spring frost around Jan 31 and a first fall frost around Dec 28. These are zone averages — look up your ZIP for your exact area.
See the full Zone 10a calendar in the tool →