USDA hardiness zones — 2023 map
Iowa hardiness zones — USDA planting zone map + what to grow
Zones 4b-6a · most of Iowa is zone 5b · Midwest region
IowaUSDA zone range & map
On the 2023 USDA Plant Hardiness Zone Map, Iowa spans zones 4b-6a. The map shades the state from the northern counties near Minnesota (zone 4b) through to the southeast along the Mississippi (zone 6a). The single most common half-zone across the populated state is zone 5b — that is the figure to use if you only remember one number for Iowa. Iowa has a classic continental prairie climate — cold winters, hot humid summers, and a strong but bounded growing season.
| USDA zone range | Zones 4b-6a |
|---|---|
| Most common zone | Zone 5b |
| Coldest area | the northern counties near Minnesota (zone 4b) |
| Warmest area | the southeast along the Mississippi (zone 6a) |
| Average last spring frost | late April |
| Average first fall frost | early October |
Source: USDA 2023 Plant Hardiness Zone Map (1991-2020 normals). Frost averages: NOAA/NCEI 1991-2020 climate normals. Local ZIP-level zones and frost dates can differ from these statewide figures.
Iowa hardiness zones by major city
Zones shift across Iowa with elevation and distance from the coast. Here is the 2023 USDA half-zone for the largest cities:
| City | USDA zone |
|---|---|
| Des Moines | Zone 5b |
| Cedar Rapids | Zone 5a |
| Davenport | Zone 5b |
| Sioux City | Zone 5a |
Need your exact zone? Run the ZIP-code zone finder for a precise half-zone and frost dates for your address.
ZIP-code zones in Iowa
Statewide ranges hide a lot. Tap your area for its exact USDA half-zone, last and first frost dates, and what to plant now:
- Ames 50010 — Zone 5a
- West Des Moines 50265 — Zone 5b
- Des Moines 50309 — Zone 5b
- Des Moines (North) 50314 — Zone 5b
- Cedar Falls 50613 — Zone 5a
- Waterloo 50701 — Zone 5a
- Sioux City 51101 — Zone 5a
- Dubuque 52001 — Zone 5a
- Iowa City 52240 — Zone 5b
- Cedar Rapids 52401 — Zone 5a
- Cedar Rapids (Southwest) 52404 — Zone 5a
- Davenport 52801 — Zone 5b
What Iowa's zone range means for planting
Your hardiness zone tells you which perennials, shrubs, and trees will survive a typical Iowa winter, and it anchors when tender crops can go outside. Because Iowa spans 4b-6a, two gardeners in the same state can have very different planting calendars.
- Pick perennials hardy to your local zone. Across most of Iowa that means at least zone 5b; gardeners in the northern counties near Minnesota (zone 4b) should choose hardier plants.
- Anchor tender crops to your frost dates. With a last spring frost around late April and first fall frost around early October, set out tomatoes, peppers, and basil after the last frost and protect them before the first.
- Adjust for your microclimate. Urban heat, a south-facing slope, or a cold valley pocket can shift your effective zone and frost dates by a half-zone or more from the statewide figure.
Find your exact zone in Iowa
The 4b-6a range is statewide. Growli pins your hardiness zone and frost dates to your exact ZIP code and sends a push notification before any forecast frost night for your saved location.
Frequently asked questions
What hardiness zone is Iowa?
Iowa spans USDA hardiness zones 4b-6a on the 2023 USDA Plant Hardiness Zone Map. The most common zone — covering the largest share of the populated state — is zone 5b. The coldest areas are the northern counties near Minnesota (zone 4b) and the warmest are the southeast along the Mississippi (zone 6a).
When is the last frost in Iowa?
Across most of Iowa the average last spring frost falls around late April and the first fall frost around early October. These are statewide averages — colder, higher areas run later in spring and earlier in fall, so check a ZIP-level estimate for your exact spot.
What grows well in Iowa?
Iowa has a classic continental prairie climate — cold winters, hot humid summers, and a strong but bounded growing season. Match plants to your local half-zone within the 4b-6a range: choose varieties hardy to at least zone 5b for reliable overwintering, and time tender crops around your local frost dates. The zone 5 planting guide lists vegetables, fruit, and ornamentals suited to most of the state.
Why does Iowa have more than one hardiness zone?
Hardiness zones track the average annual coldest temperature, which changes with latitude, elevation, distance from water, and urban heat. That is why Iowa ranges from the northern counties near Minnesota (zone 4b) to the southeast along the Mississippi (zone 6a) — a span of 4b-6a — even though it is a single state.
Did Iowa's hardiness zone change in 2023?
The USDA updated the Plant Hardiness Zone Map in November 2023 using 1991-2020 climate data. About half the country, including parts of Iowa, shifted to the next warmer half-zone versus the 2012 map. The 4b-6a range here reflects the current 2023 map. Always confirm your address against the official USDA map for plant-survival decisions.