When to plant onions in Iowa

Onions
Plant out in Des Moines
Mar 7–Mar 28

Across Iowa the window opens between March 4 and March 18. Find your city below; the dates follow each town's own average last frost.

Start indoors, Des Moines
Jan 24–Feb 21
Plant out, Des Moines
Mar 7–Mar 28
Last frost, Des Moines
Apr 18

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
Des MoinesMar 7–Mar 28
Cedar RapidsMar 16–Apr 6
DavenportMar 8–Mar 29
Sioux CityMar 18–Apr 8
AnkenyMar 12–Apr 2
Iowa CityMar 10–Mar 31
West Des MoinesMar 7–Mar 28
AmesMar 15–Apr 5
WaterlooMar 16–Apr 6
Council BluffsMar 7–Mar 28
DubuqueMar 8–Mar 29
UrbandaleMar 8–Mar 29
MarionMar 17–Apr 7
Cedar FallsMar 16–Apr 6
BettendorfMar 5–Mar 26
WaukeeMar 7–Mar 28
MarshalltownMar 17–Apr 7
Mason CityMar 18–Apr 8
OttumwaMar 12–Apr 2
JohnstonMar 8–Mar 29
Fort DodgeMar 17–Apr 7
ClintonMar 11–Apr 1
CoralvilleMar 10–Mar 31
BurlingtonMar 4–Mar 25
MuscatineMar 13–Apr 3
AltoonaMar 12–Apr 2
North LibertyMar 10–Mar 31

Questions

When should I plant onions in Iowa?

In Des Moines, plant out from March 7 to March 28. Across Iowa the window opens between March 4 and March 18, 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 Iowa

Onions in other states

Frost dates for every city in Iowa