Deconstruct SunIowa Hardiness Zones
Iowa covers USDA plant hardiness zones 4b to 6a on the 2023 map, so its coldest areas average −25 to −20 °F on the coldest winter night. Find your zone by ZIP code, or pick a city below for its zone, sunrise and daylight by month.
Iowa hardiness zone map
This is not the official USDA Plant Hardiness Zone Map. Zones are derived from the official 2023 dataset, resampled to about 2 km. Dots mark cities with their own page.
Source: USDA Plant Hardiness Zone Map, 2023. Agricultural Research Service, U.S. Department of Agriculture, planthardiness.ars.usda.gov. Underlying data © PRISM Group, Oregon State University, prism.oregonstate.edu, accessed 2026-08-30.
Zones and daylight by city
| City | Zone | Coldest night | Longest day | Shortest day |
|---|---|---|---|---|
| Des Moines | 5b | −15 to −10 °F | 15h 12m | 9h 10m |
| Cedar Rapids | 5b | −15 to −10 °F | 15h 14m | 9h 07m |
| Davenport | 5b | −15 to −10 °F | 15h 12m | 9h 10m |
| Sioux City | 5a | −20 to −15 °F | 15h 18m | 9h 04m |
| Iowa City | 5b | −15 to −10 °F | 15h 12m | 9h 09m |
| Ames | 5b | −15 to −10 °F | 15h 15m | 9h 07m |
| Dubuque | 5a | −20 to −15 °F | 15h 18m | 9h 04m |
Gardening in Iowa?
Your zone says what survives winter. Deconstruct Sun measures how many hours of direct sun your exact spot gets, so you can pick plants that thrive. Free on iPhone.
Questions
What hardiness zones are in Iowa?
Iowa spans USDA zones 4b to 6a on the 2023 map. Among its larger cities, Sioux City is coldest (zone 5a) and Des Moines is warmest (zone 5b).
How do I find my exact zone in Iowa?
Enter your ZIP code in the hardiness zone lookup on this site. It reads the 2023 USDA data for that ZIP and warns you if you are near a zone boundary.
How much sun do gardens in Iowa get?
In Des Moines, an open spot gets up to 15.2 hours of daylight in June but only 9.2 in December. Trees and buildings cut that down, especially in winter. The Deconstruct Sun app measures the real direct-sun hours for one exact spot.