When to Plant Onions in Zone 3
In USDA zone 3a, start seeds indoors around March 21, transplant or plant outdoors May 2 to August 20, and expect your first harvest around August 20. (3a shown here — see 3a and 3b dates separately below.)
Onions planting calendar for USDA Zone 3a
Average last spring frost
May 30
Average first fall frost
September 10
Start seeds indoors
Mar 21
Transplant outdoors
May 2
Projected first harvest
Aug 20
Most onions mature in about 90 to 110 days depending on the variety, needing roughly 103 frost-free days in zone 3a.
Onions planting calendar for USDA Zone 3b
Average last spring frost
May 20
Average first fall frost
September 15
Start seeds indoors
Mar 11
Transplant outdoors
Apr 22
Projected first harvest
Aug 10
Most onions mature in about 90 to 110 days depending on the variety, needing roughly 118 frost-free days in zone 3b.
Not sure whether you're in 3a or 3b? 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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