When to Plant Onions in Zone 9
In USDA zone 9a, start seeds indoors around December 21, transplant or plant outdoors February 1 to May 22, and expect your first harvest around May 22. (9a shown here — see 9a and 9b dates separately below.)
Onions planting calendar for USDA Zone 9a
Average last spring frost
March 1
Average first fall frost
December 1
Start seeds indoors
Dec 21
Transplant outdoors
Feb 1
Projected first harvest
May 22
Most onions mature in about 90 to 110 days depending on the variety, needing roughly 275 frost-free days in zone 9a.
Onions planting calendar for USDA Zone 9b
Average last spring frost
February 15
Average first fall frost
December 15
Start seeds indoors
Dec 7
Transplant outdoors
Jan 18
Projected first harvest
May 8
Most onions mature in about 90 to 110 days depending on the variety, needing roughly 303 frost-free days in zone 9b.
Not sure whether you're in 9a or 9b? Set your ZIP in HomeSown for dates tuned to your exact location.
Varieties to grow
8 varieties of onions in the HomeSown library. Tap any for its full grow guide.
Common problems with onions
What to watch for, with identification and treatment for each
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