When to plant Sweet corn in Iowa

In spring, from Apr 10 – June 1 in Burlington to May 10 – June 15 in Waverly.

In fall, June 1 – July 10.

USDA's earliest safe spring and latest safe fall planting dates, matched to each place's average frost dates.

Sweet corn planting dates by place in Iowa
PlaceSpringFall
AltoonaApr 25 – June 15June 1 – July 10
AmesMay 10 – June 15June 1 – July 10
AnkenyApr 25 – June 15June 1 – July 10
BettendorfApr 25 – June 15June 1 – July 20
BooneMay 10 – June 15June 1 – July 10
BurlingtonApr 10 – June 1June 1 – July 20
CarrollMay 10 – June 15June 1 – July 10
Cedar FallsMay 10 – June 15June 1 – July 10
Cedar RapidsMay 10 – June 15June 1 – July 10
ClintonApr 25 – June 15June 1 – July 20
CliveApr 25 – June 15June 1 – July 20
CoralvilleApr 25 – June 15June 1 – July 20
Council BluffsApr 25 – June 15June 1 – July 20
DavenportApr 25 – June 15June 1 – July 20
Des MoinesApr 25 – June 15June 1 – July 20
DubuqueApr 25 – June 15June 1 – July 20
Fort DodgeMay 10 – June 15June 1 – July 10
GrimesApr 25 – June 15June 1 – July 20
IndianolaApr 25 – June 15June 1 – July 10
Iowa CityApr 25 – June 15June 1 – July 20
JohnstonApr 25 – June 15June 1 – July 20
Le MarsMay 10 – June 15June 1 – July 1
MarionMay 10 – June 15June 1 – July 10
MarshalltownMay 10 – June 15June 1 – July 10
Mason CityMay 10 – June 15June 1 – July 10
MuscatineApr 25 – June 15June 1 – July 10
NewtonApr 25 – June 15June 1 – July 20
North LibertyApr 25 – June 15June 1 – July 20
NorwalkApr 25 – June 15June 1 – July 20
OskaloosaApr 25 – June 15June 1 – July 20
OttumwaApr 25 – June 15June 1 – July 10
PellaApr 25 – June 15June 1 – July 20
Pleasant HillApr 25 – June 15June 1 – July 20
Sioux CityMay 10 – June 15June 1 – July 10
SpencerMay 10 – June 15June 1 – July 1
Storm LakeApr 25 – June 15June 1 – July 10
UrbandaleApr 25 – June 15June 1 – July 20
WaterlooMay 10 – June 15June 1 – July 10
WaukeeApr 25 – June 15June 1 – July 20
WaverlyMay 10 – June 15June 1 – July 10
West Des MoinesApr 25 – June 15June 1 – July 20

Planting dates: USDA Home and Garden Bulletin No. 9 (1967), tables 4 and 5. Frost dates: NOAA U.S. Climate Normals 1991–2020. “—” means the place's frost date is outside the table. The full USDA table for sweet corn.