When to Plant Onions in Illinois
Illinois spans USDA hardiness 5a to 7a (zones 5a to 7a on this page). Plant onions by your local frost date, not the calendar — pick your zone below for exact start-indoors, transplant, and harvest dates.
Jump to: Zone 5a · Zone 5b · Zone 6a · Zone 6b · Zone 7a
Onions planting calendar for Illinois, Zone 5a
Average last spring frost
May 5
Average first fall frost
October 1
Direct sow
Feb 10
Projected first harvest
May 31
Most onions mature in about 90 to 110 days depending on the variety. Full zone 5 guide (both 5a and 5b) →
Onions planting calendar for Illinois, Zone 5b
Average last spring frost
April 30
Average first fall frost
October 5
Direct sow
Feb 5
Projected first harvest
May 26
Most onions mature in about 90 to 110 days depending on the variety. Full zone 5 guide (both 5a and 5b) →
Onions planting calendar for Illinois, Zone 6a
Average last spring frost
April 25
Average first fall frost
October 10
Direct sow
Jan 31
Projected first harvest
May 21
Most onions mature in about 90 to 110 days depending on the variety. Full zone 6 guide (both 6a and 6b) →
Onions planting calendar for Illinois, Zone 6b
Average last spring frost
April 20
Average first fall frost
October 15
Direct sow
Jan 26
Projected first harvest
May 16
Most onions mature in about 90 to 110 days depending on the variety. Full zone 6 guide (both 6a and 6b) →
Onions planting calendar for Illinois, Zone 7a
Average last spring frost
April 15
Average first fall frost
October 20
Direct sow
Jan 21
Projected first harvest
May 11
Most onions mature in about 90 to 110 days depending on the variety. Full zone 7 guide (both 7a and 7b) →
Not sure which half-zone you're in? 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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