South Carolina · zones 8a–9a
When to plant onions in South Carolina.
Sow or transplant between Jan 17 to Mar 2 in a typical year, keyed to South Carolina's median last frost around Mar 27. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Onions dates for a typical South Carolina season.
1 · Start indoors
Dec 6 to Jan 19
About 6 weeks before set-out. Warm spot, real light.
2 · Set out
Jan 17 to Mar 2
Keyed to the ~Mar 27 last frost. Sow 0.5" deep, 4" apart.
Harvest
~95 days later
~0.5 lb per plant over ~1 weeks.
South Carolina spans more than one climate: Zone 8 is the most common zone, but the state runs 8a to 9a. 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.