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When to Plant Onions in New Hampshire

New Hampshire spans USDA hardiness 4a to 6b (zones 4a to 6b 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 4a · Zone 4b · Zone 5a · Zone 5b · Zone 6a · Zone 6b

Onions planting calendar for New Hampshire, Zone 4a

Average last spring frost

May 15

Average first fall frost

September 20

🌿

Direct sow

Feb 20

🌾

Projected first harvest

Jun 10

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. Full zone 4 guide (both 4a and 4b) →

Onions planting calendar for New Hampshire, Zone 4b

Average last spring frost

May 10

Average first fall frost

September 25

🌿

Direct sow

Feb 15

🌾

Projected first harvest

Jun 5

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. Full zone 4 guide (both 4a and 4b) →

Onions planting calendar for New Hampshire, Zone 5a

Average last spring frost

May 5

Average first fall frost

October 1

🌿

Direct sow

Feb 10

🌾

Projected first harvest

May 31

J
F
M
A
M
J
J
A
S
O
N
D
🌱 Start indoors🌿 Growing outside🌾 HarvestTodayZone 5a (approximate)

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 New Hampshire, Zone 5b

Average last spring frost

April 30

Average first fall frost

October 5

🌿

Direct sow

Feb 5

🌾

Projected first harvest

May 26

J
F
M
A
M
J
J
A
S
O
N
D
🌱 Start indoors🌿 Growing outside🌾 HarvestTodayZone 5b (approximate)

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 New Hampshire, Zone 6a

Average last spring frost

April 25

Average first fall frost

October 10

🌿

Direct sow

Jan 31

🌾

Projected first harvest

May 21

J
F
M
A
M
J
J
A
S
O
N
D
🌱 Start indoors🌿 Growing outside🌾 HarvestTodayZone 6a (approximate)

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 New Hampshire, Zone 6b

Average last spring frost

April 20

Average first fall frost

October 15

🌿

Direct sow

Jan 26

🌾

Projected first harvest

May 16

J
F
M
A
M
J
J
A
S
O
N
D
🌱 Start indoors🌿 Growing outside🌾 HarvestTodayZone 6b (approximate)

Most onions mature in about 90 to 110 days depending on the variety. Full zone 6 guide (both 6a and 6b) →

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.

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 →

onions — full zone guide

All zonesZone 4 →Zone 5 →Zone 6 →