California · zones 7a–10b
When to plant onions in California.
Sow or transplant between Jan 1 to Jan 1 in a typical year, keyed to California's median last frost around Jan 14. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Onions dates for a typical California season.
1 · Start indoors
Nov 20 to Nov 20
About 6 weeks before set-out. Warm spot, real light.
2 · Set out
Jan 1 to Jan 1
Keyed to the ~Jan 14 last frost. Sow 0.5" deep, 4" apart.
Harvest
~95 days later
~0.5 lb per plant over ~1 weeks.
California spans more than one climate: Zone 10 is the most common zone, but the state runs 7a to 10b. That's why the planner works from your ZIP code's frost dates, not your zone — mountain and coastal gardens in the same state can be three weeks apart.