FrostCal

When to Plant Watermelon in Iowa

In a typical Iowa location, start seeds indoors Mar 24 – Mar 31, then transplant outdoors May 5 – May 12. Across the state, the outdoor planting window starts as early as Apr 24 in Keokuk and as late as May 17 in Grinnell.

Method Start indoors, then transplant
Days to maturity 70–90 days

Needs warm soil (65F+); start indoors 3-4 weeks before last frost, transplant 2-3 weeks after last frost.

Watermelon Planting Dates by City

CityStart indoorsTransplant
Des MoinesMar 21 – Mar 28May 2 – May 9
Cedar RapidsMar 31 – Apr 7May 12 – May 19
DavenportMar 22 – Mar 29May 3 – May 10
Sioux CityApr 1 – Apr 8May 13 – May 20
Iowa CityMar 24 – Mar 31May 5 – May 12
WaterlooMar 30 – Apr 6May 11 – May 18
AmesMar 29 – Apr 5May 10 – May 17
West Des MoinesMar 21 – Mar 28May 2 – May 9
Council BluffsMar 21 – Mar 28May 2 – May 9
DubuqueMar 22 – Mar 29May 3 – May 10
AnkenyMar 26 – Apr 2May 7 – May 14
UrbandaleMar 21 – Mar 28May 2 – May 9
Cedar FallsMar 30 – Apr 6May 11 – May 18
MarionMar 31 – Apr 7May 12 – May 19
BettendorfMar 22 – Mar 29May 3 – May 10
MarshalltownMar 31 – Apr 7May 12 – May 19
Mason CityApr 1 – Apr 8May 13 – May 20
ClintonMar 16 – Mar 23Apr 27 – May 4
BurlingtonMar 18 – Mar 25Apr 29 – May 6
Fort DodgeMar 31 – Apr 7May 12 – May 19
OttumwaMar 26 – Apr 2May 7 – May 14
MuscatineMar 21 – Mar 28May 2 – May 9
JohnstonMar 22 – Mar 29May 3 – May 10
CoralvilleMar 24 – Mar 31May 5 – May 12
WaukeeMar 22 – Mar 29May 3 – May 10
AltoonaMar 24 – Mar 31May 5 – May 12
North LibertyMar 24 – Mar 31May 5 – May 12
IndianolaMar 27 – Apr 3May 8 – May 15
CliveMar 21 – Mar 28May 2 – May 9
NewtonMar 25 – Apr 1May 6 – May 13

Showing the 30 most populous of 45 Iowa cities. Dates are estimates from each city's NOAA frost normals and university extension timing guidelines. See all Iowa cities.

Frequently Asked Questions

When should I plant watermelon in Iowa?

In a typical Iowa location, start seeds indoors Mar 24 – Mar 31, then transplant outdoors May 5 – May 12. Across the state, the outdoor planting window starts as early as Apr 24 in Keokuk and as late as May 17 in Grinnell.

When is the last frost in Iowa?

The average last spring frost in Iowa ranges from April 10 in Keokuk to May 3 in Grinnell, based on NOAA 1991–2020 climate normals.

How long do watermelon take to grow?

Watermelon typically take 70–90 days from planting to harvest. Needs warm soil (65F+); start indoors 3-4 weeks before last frost, transplant 2-3 weeks after last frost.

Other Crops in Iowa

When to plant watermelon in other states

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