When to Plant Onions in Washington
Washington spans USDA hardiness 6a to 9b (zones 6a to 9b 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 6a · Zone 6b · Zone 7a · Zone 7b · Zone 8a · Zone 8b · Zone 9a · Zone 9b
Onions planting calendar for Washington, 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 Washington, 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 Washington, 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) →
Onions planting calendar for Washington, Zone 7b
Average last spring frost
April 10
Average first fall frost
October 30
Direct sow
Jan 16
Projected first harvest
May 6
Most onions mature in about 90 to 110 days depending on the variety. Full zone 7 guide (both 7a and 7b) →
Onions planting calendar for Washington, Zone 8a
Average last spring frost
April 1
Average first fall frost
November 10
Direct sow
Jan 7
Projected first harvest
Apr 27
Most onions mature in about 90 to 110 days depending on the variety. Full zone 8 guide (both 8a and 8b) →
Onions planting calendar for Washington, Zone 8b
Average last spring frost
March 20
Average first fall frost
November 20
Direct sow
Dec 26
Projected first harvest
Apr 15
Most onions mature in about 90 to 110 days depending on the variety. Full zone 8 guide (both 8a and 8b) →
Onions planting calendar for Washington, Zone 9a
Average last spring frost
March 1
Average first fall frost
December 1
Direct sow
Dec 7
Projected first harvest
Mar 27
Most onions mature in about 90 to 110 days depending on the variety. Full zone 9 guide (both 9a and 9b) →
Onions planting calendar for Washington, Zone 9b
Average last spring frost
February 15
Average first fall frost
December 15
Direct sow
Nov 23
Projected first harvest
Mar 13
Most onions mature in about 90 to 110 days depending on the variety. Full zone 9 guide (both 9a and 9b) →
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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