FrostCal

When to Plant Cosmos in Wisconsin

In a typical Wisconsin location, start seeds indoors Apr 2 – Apr 9, then sow outdoors May 7 – May 21, then transplant outdoors May 7 – May 14. Across the state, the outdoor planting window starts as early as Apr 26 in Kenosha and as late as May 18 in Merrill.

Method Direct sow
Days to maturity 60–90 days

Easy from direct seed 1-3 weeks after last frost; can also start indoors 3-4 weeks early.

Cosmos Planting Dates by City

CityStart indoorsDirect sowTransplant
MilwaukeeMar 29 – Apr 5May 3 – May 17May 3 – May 10
MadisonApr 3 – Apr 10May 8 – May 22May 8 – May 15
Green BayApr 9 – Apr 16May 14 – May 28May 14 – May 21
KenoshaMar 22 – Mar 29Apr 26 – May 10Apr 26 – May 3
RacineMar 23 – Mar 30Apr 27 – May 11Apr 27 – May 4
AppletonApr 6 – Apr 13May 11 – May 25May 11 – May 18
WaukeshaApr 3 – Apr 10May 8 – May 22May 8 – May 15
Eau ClaireMar 27 – Apr 3May 1 – May 15May 1 – May 8
OshkoshMar 27 – Apr 3May 1 – May 15May 1 – May 8
JanesvilleMar 29 – Apr 5May 3 – May 17May 3 – May 10
West AllisMar 29 – Apr 5May 3 – May 17May 3 – May 10
La CrosseMar 30 – Apr 6May 4 – May 18May 4 – May 11
North La CrosseMar 26 – Apr 2Apr 30 – May 14Apr 30 – May 7
SheboyganMar 28 – Apr 4May 2 – May 16May 2 – May 9
WauwatosaMar 29 – Apr 5May 3 – May 17May 3 – May 10
Fond du LacMar 30 – Apr 6May 4 – May 18May 4 – May 11
New BerlinApr 5 – Apr 12May 10 – May 24May 10 – May 17
WausauApr 8 – Apr 15May 13 – May 27May 13 – May 20
BrookfieldApr 2 – Apr 9May 7 – May 21May 7 – May 14
GreenfieldApr 5 – Apr 12May 10 – May 24May 10 – May 17
BeloitApr 3 – Apr 10May 8 – May 22May 8 – May 15
FranklinApr 5 – Apr 12May 10 – May 24May 10 – May 17
Menomonee FallsApr 8 – Apr 15May 13 – May 27May 13 – May 20
Oak CreekMar 25 – Apr 1Apr 29 – May 13Apr 29 – May 6
ManitowocApr 2 – Apr 9May 7 – May 21May 7 – May 14
Sun PrairieApr 3 – Apr 10May 8 – May 22May 8 – May 15
West BendApr 3 – Apr 10May 8 – May 22May 8 – May 15
FitchburgApr 3 – Apr 10May 8 – May 22May 8 – May 15
Stevens PointApr 6 – Apr 13May 11 – May 25May 11 – May 18
SuperiorApr 8 – Apr 15May 13 – May 27May 13 – May 20

Showing the 30 most populous of 96 Wisconsin cities. Dates are estimates from each city's NOAA frost normals and university extension timing guidelines. See all Wisconsin cities.

Frequently Asked Questions

When should I plant cosmos in Wisconsin?

In a typical Wisconsin location, start seeds indoors Apr 2 – Apr 9, then sow outdoors May 7 – May 21, then transplant outdoors May 7 – May 14. Across the state, the outdoor planting window starts as early as Apr 26 in Kenosha and as late as May 18 in Merrill.

When is the last frost in Wisconsin?

The average last spring frost in Wisconsin ranges from April 19 in Kenosha to May 11 in Merrill, based on NOAA 1991–2020 climate normals.

How long do cosmos take to grow?

Cosmos typically take 60–90 days from planting to harvest. Easy from direct seed 1-3 weeks after last frost; can also start indoors 3-4 weeks early.

Other Crops in Wisconsin

When to plant cosmos in other states

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