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When to Plant Onions in Zone 4

In USDA zone 4a, start seeds indoors around March 6, transplant or plant outdoors April 17 to August 5, and expect your first harvest around August 5. (4a shown here — see 4a and 4b dates separately below.)

Onions planting calendar for USDA Zone 4a

Average last spring frost

May 15

Average first fall frost

September 20

🌱

Start seeds indoors

Mar 6

🌿

Transplant outdoors

Apr 17

🌾

Projected first harvest

Aug 5

J
F
M
A
M
J
J
A
S
O
N
D
🌱 Start indoors🌿 Growing outside🌾 HarvestTodayZone 4a (approximate)

Most onions mature in about 90 to 110 days depending on the variety, needing roughly 128 frost-free days in zone 4a.

Onions planting calendar for USDA Zone 4b

Average last spring frost

May 10

Average first fall frost

September 25

🌱

Start seeds indoors

Mar 1

🌿

Transplant outdoors

Apr 12

🌾

Projected first harvest

Jul 31

J
F
M
A
M
J
J
A
S
O
N
D
🌱 Start indoors🌿 Growing outside🌾 HarvestTodayZone 4b (approximate)

Most onions mature in about 90 to 110 days depending on the variety, needing roughly 138 frost-free days in zone 4b.

Not sure whether you're in 4a or 4b? 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.

Cipollini Onion →Pearl Onion →Red Onion →Spanish Onion →Vidalia Sweet Onion →Walla Walla Sweet Onion →White Onion →Yellow Sweet Onion →

Common problems with onions

What to watch for, with identification and treatment for each

Onion MaggotLeek MothSeed Corn MaggotSeedcorn MaggotBulb MiteWirewormsPink RootBotrytis Neck RotFusarium Basal RotWhite RotCracking & SplittingBulb Rot

🌱 Grow onions with a calendar built for your exact yard

HomeSown turns your ZIP code into a personalized planting calendar, watering reminders, and pest help. Free to start.

Start your free garden →

When to plant onions in other zones

All zonesZone 3 →Zone 5 →Zone 6 →Zone 7 →Zone 8 →Zone 9 →Zone 10 →