When to plant onions in Wisconsin

Onions
Plant out in Milwaukee
Mar 15–Apr 5

Across Wisconsin the window opens between March 8 and March 26. Find your city below; the dates follow each town's own average last frost.

Start indoors, Milwaukee
Feb 1–Mar 1
Plant out, Milwaukee
Mar 15–Apr 5
Last frost, Milwaukee
Apr 26

Start seeds indoors 8–12 weeks before the last frost; plant out 3–6 weeks before the last frost. Northern gardens need long-day varieties and southern gardens need short-day ones. A wrong pick gives small bulbs.

Onions planting dates by city

Start indoorsPlant outSow outdoorsFall plantingAverage last and first frost
JanFebMarAprMayJunJulAugSepOctNovDec
MilwaukeeMar 15–Apr 5
MadisonMar 20–Apr 10
Green BayMar 26–Apr 16
KenoshaMar 17–Apr 7
RacineMar 9–Mar 30
AppletonMar 23–Apr 13
Eau ClaireMar 13–Apr 3
WaukeshaMar 20–Apr 10
OshkoshMar 13–Apr 3
JanesvilleMar 15–Apr 5
West AllisMar 15–Apr 5
La CrosseMar 16–Apr 6
SheboyganMar 14–Apr 4
WauwatosaMar 15–Apr 5
Fond du LacMar 16–Apr 6
BrookfieldMar 19–Apr 9
Menomonee FallsMar 25–Apr 15
WausauMar 25–Apr 15
New BerlinMar 22–Apr 12
Sun PrairieMar 20–Apr 10
Oak CreekMar 11–Apr 1
GreenfieldMar 22–Apr 12
FranklinMar 22–Apr 12
BeloitMar 20–Apr 10
ManitowocMar 19–Apr 9
FitchburgMar 20–Apr 10
West BendMar 20–Apr 10
Mount PleasantMar 9–Mar 30
NeenahMar 23–Apr 13
SuperiorMar 25–Apr 15
All 43 cities
CityStart indoorsPlant outLast frost
MilwaukeeFeb 1 to Mar 1Mar 15 to Apr 5Apr 26
MadisonFeb 6 to Mar 6Mar 20 to Apr 10May 1
Green BayFeb 12 to Mar 12Mar 26 to Apr 16May 7
KenoshaFeb 3 to Mar 3Mar 17 to Apr 7Apr 28
RacineJan 26 to Feb 23Mar 9 to Mar 30Apr 20
AppletonFeb 9 to Mar 9Mar 23 to Apr 13May 4
Eau ClaireJan 30 to Feb 27Mar 13 to Apr 3Apr 24
WaukeshaFeb 6 to Mar 6Mar 20 to Apr 10May 1
OshkoshJan 30 to Feb 27Mar 13 to Apr 3Apr 24
JanesvilleFeb 1 to Mar 1Mar 15 to Apr 5Apr 26
West AllisFeb 1 to Mar 1Mar 15 to Apr 5Apr 26
La CrosseFeb 2 to Mar 2Mar 16 to Apr 6Apr 27
SheboyganJan 31 to Feb 28Mar 14 to Apr 4Apr 25
WauwatosaFeb 1 to Mar 1Mar 15 to Apr 5Apr 26
Fond du LacFeb 2 to Mar 2Mar 16 to Apr 6Apr 27
BrookfieldFeb 5 to Mar 5Mar 19 to Apr 9Apr 30
Menomonee FallsFeb 11 to Mar 11Mar 25 to Apr 15May 6
WausauFeb 11 to Mar 11Mar 25 to Apr 15May 6
New BerlinFeb 8 to Mar 8Mar 22 to Apr 12May 3
Sun PrairieFeb 6 to Mar 6Mar 20 to Apr 10May 1
Oak CreekJan 28 to Feb 25Mar 11 to Apr 1Apr 22
GreenfieldFeb 8 to Mar 8Mar 22 to Apr 12May 3
FranklinFeb 8 to Mar 8Mar 22 to Apr 12May 3
BeloitFeb 6 to Mar 6Mar 20 to Apr 10May 1
ManitowocFeb 5 to Mar 5Mar 19 to Apr 9Apr 30
FitchburgFeb 6 to Mar 6Mar 20 to Apr 10May 1
West BendFeb 6 to Mar 6Mar 20 to Apr 10May 1
Mount PleasantJan 26 to Feb 23Mar 9 to Mar 30Apr 20
NeenahFeb 9 to Mar 9Mar 23 to Apr 13May 4
SuperiorFeb 11 to Mar 11Mar 25 to Apr 15May 6
Stevens PointFeb 9 to Mar 9Mar 23 to Apr 13May 4
MuskegoFeb 8 to Mar 8Mar 22 to Apr 12May 3
De PereFeb 5 to Mar 5Mar 19 to Apr 9Apr 30
CaledoniaJan 30 to Feb 27Mar 13 to Apr 3Apr 24
MequonFeb 11 to Mar 11Mar 25 to Apr 15May 6
MiddletonFeb 3 to Mar 3Mar 17 to Apr 7Apr 28
WatertownFeb 3 to Mar 3Mar 17 to Apr 7Apr 28
HowardFeb 12 to Mar 12Mar 26 to Apr 16May 7
Pleasant PrairieJan 25 to Feb 22Mar 8 to Mar 29Apr 19
GermantownFeb 11 to Mar 11Mar 25 to Apr 15May 6
OnalaskaJan 29 to Feb 26Mar 12 to Apr 2Apr 23
South MilwaukeeJan 28 to Feb 25Mar 11 to Apr 1Apr 22
OconomowocFeb 5 to Mar 5Mar 19 to Apr 9Apr 30

Questions

When should I plant onions in Wisconsin?

In Milwaukee, plant out from March 15 to April 5. Across Wisconsin the window opens between March 8 and March 26, depending on the local last frost.

How is this date worked out?

Start seeds indoors 8–12 weeks before the last frost; plant out 3–6 weeks before the last frost. Frost dates are NOAA 1991–2020 averages for the weather station nearest each city.

More for Wisconsin

Onions in other states

Frost dates for every city in Wisconsin