State growing guide
Iowa Planting Guide
USDA Zone 5a/5b · Last frost May 1 · First frost Oct 10 · 162 days
Zone-specific planting calendar, major city frost dates, top crops, and Duke's tips for growing food in Iowa.
Frost Dates by City — Iowa
Average frost dates for major Iowa cities. Use these to calculate your indoor start dates and transplant windows.
| City | USDA Zone | Last Spring Frost | First Fall Frost | Tomato Transplant Window |
|---|---|---|---|---|
| Des Moines | 5a | May 1 | Oct 10 | ~2 wks after (May 1) |
| Sioux City | 5a | May 3 | Oct 8 | ~2 wks after (May 3) |
| Cedar Rapids | 5a | Apr 30 | Oct 12 | ~2 wks after (Apr 30) |
| Iowa City | 5b | Apr 25 | Oct 15 | ~2 wks after (Apr 25) |
| Dubuque | 5a | May 3 | Oct 8 | ~2 wks after (May 3) |
Average dates based on 30-year NOAA climate normals. Individual years may vary ±2 weeks. Use the Zone Lookup Tool for ZIP-specific dates.
Duke's Top Tips for Iowa Gardeners
- Iowa has a reliable growing season despite the cold winters
- Plant potatoes on Good Friday is a tradition — roughly mid-April
- Iowa summers are hot and humid — perfect for sweet corn and squash
- Plant a fall garden in late July for October harvest
Common Challenges in Iowa
- ⚠ Unpredictable late May frosts — protect transplants until May 10
- ⚠ Heavy clay soils compact easily — till in compost each spring
- ⚠ Corn earworm is common in garden sweet corn
Best Crops for Iowa
Get exact dates for your ZIP code in Iowa
City averages are a starting point. Your actual microclimate matters — enter your ZIP for precise frost dates.
Frequently Asked Questions — Iowa Gardening
What zone is Iowa?
Iowa is Zones 4b (far northwest corner) to 5b (southeast). Des Moines is Zone 5a with last frost around May 1.
When to plant tomatoes in Iowa?
Start seeds indoors mid-March. Transplant outside after May 10 to be safe. Some years May 1 is fine, but late frosts in early May do occur.