How long do onions take to grow?

Most onions mature in about 90 to 110 days depending on the variety, measured from planting.

When to Plant Onions in Zone 4

In USDA zone 4, start seeds indoors around March 6, transplant or plant outdoors April 17 to August 5, and expect your first harvest around August 5.

Onions planting calendar for USDA Zone 4

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Start seeds indoors

Mar 6

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Transplant outdoors

Apr 17

🌾

Projected first harvest

Aug 5

JJan

FFeb

MMar

AApr

MMay

JJun

JJul

AAug

SSep

OOct

NNov

DDec

🌱 Start indoors🌿 Growing outside🌾 HarvestTodayZone 4a — approximate

Most onions mature in about 90 to 110 days depending on the variety. Dates use USDA zone 4a average frost dates. Set your ZIP in HomeSown for dates tuned to your exact location.

What zone 4 means for onions

Average last spring frost

May 15

Average first fall frost

September 20

Those two dates are what set the schedule above. Zone 4 gives you roughly 128 frost-free days, and onions need about 90 to 110 days depending on the variety to mature.

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 Maggot Leek Moth Seed Corn Maggot Seedcorn Maggot Bulb Mite Wireworms Pink Root Botrytis Neck Rot Fusarium Basal Rot White Rot Cracking & Splitting Bulb 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 zones Zone 3 →Zone 5 →Zone 6 →Zone 7 →Zone 8 →Zone 9 →Zone 10 →