Oklahoma · zones 6b–7b
When to plant onions in Oklahoma.
Sow or transplant between Jan 20 to Mar 5 in a typical year, keyed to Oklahoma's median last frost around Mar 30. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Onions dates for a typical Oklahoma season.
1 · Start indoors
Dec 9 to Jan 22
About 6 weeks before set-out. Warm spot, real light.
2 · Set out
Jan 20 to Mar 5
Keyed to the ~Mar 30 last frost. Sow 0.5" deep, 4" apart.
Harvest
~95 days later
~0.5 lb per plant over ~1 weeks.
Oklahoma spans more than one climate: Zone 7 is the most common zone, but the state runs 6b to 7b. 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.