Des Moines, Iowa: planting zone & frost dates
Des Moines is in USDA plant hardiness zone 5b, where the average coldest winter night reaches -15 to -10°F (-26.1 to -23.3°C). The typical last spring frost is around Apr 24 and the first fall frost around Oct 14.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | May 2 | Oct 4 |
| Typical planning date (30% risk) | Apr 24 | Oct 14 |
| Median (50%) | Apr 18 | Oct 20 |
How to read this: after the spring "10% risk" date, a 32°F frost happens in only about 1 year in 10. In fall, the "10% risk" date is the early end — a frost before it happens about 1 year in 10.
Frost data comes from NOAA station DES MOINES INTL AP, IA (USW00014933), 3.5 mi (5.6 km) from the city center and 164 ft higher than the city center (+50 m). Record used for the 1991–2020 normals: 26 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Des Moines
All 14 ZIP codes covering Des Moines are in zone 5b.
Vegetable planting calendar for Des Moines
Dates are counted from the 30%-risk frost dates above (last frost Apr 24, first frost Oct 14). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Feb 27 – Mar 13 | May 1 – May 15 | — | — |
| Pepper | Feb 13 – Feb 27 | May 8 – May 22 | — | — |
| Lettuce | Mar 13 – Mar 27 | Apr 10 – May 1 | Mar 27 – May 8 | Aug 5 – Sep 2 |
| Green Beans | — | — | May 1 – Jun 5 | Jul 22 – Aug 5 |
| Sweet Corn | — | — | May 1 – May 29 | — |
| Zucchini & Summer Squash | Mar 27 – Apr 3 | May 1 – May 15 | May 1 – May 22 | Jul 22 – Aug 5 |
| Cucumber | Mar 27 – Apr 3 | May 8 – May 15 | May 1 – May 22 | Jul 22 – Aug 5 |
| Carrot | — | — | Apr 3 – May 8 | Jul 22 – Aug 5 |
| Onion | Jan 30 – Feb 13 | Mar 27 – Apr 10 | — | — |
| Potato | — | Mar 27 – Apr 17 | — | — |
| Basil | Mar 13 – Mar 27 | May 8 – May 22 | May 8 – May 29 | — |
| Spinach | — | — | Mar 13 – Apr 10 | Aug 19 – Sep 16 |
| Kale | Feb 27 – Mar 13 | Mar 27 – Apr 17 | Mar 27 – Apr 17 | Aug 5 – Sep 2 |
| Broccoli | Feb 27 – Mar 13 | Apr 10 – May 1 | — | Jul 22 – Aug 5 |
| Peas | — | — | Mar 13 – Apr 3 | Aug 5 – Aug 19 |
| Eggplant | Feb 13 – Feb 27 | May 8 – May 22 | — | — |
| Cabbage | Feb 27 – Mar 13 | Mar 27 – Apr 10 | — | Jul 22 – Aug 5 |
| Radish | — | — | Mar 20 – May 8 | Sep 2 – Sep 30 |
| Strawberry | — | Mar 27 – Apr 17 | — | — |
| Beets | — | — | Apr 3 – May 15 | Aug 5 – Aug 19 |
Nearby cities in Iowa
- Ankeny — zone 5b, last frost Apr 29, first frost Oct 9
- Cedar Rapids — zone 5a, last frost May 3, first frost Oct 5
- Iowa City — zone 5b, last frost Apr 28, first frost Oct 13
- Sioux City — zone 5a, last frost May 4, first frost Oct 1
- Davenport — zone 5b, last frost Apr 24, first frost Oct 17
More: all Iowa cities · other zone 5b cities: Madison, WI, Aurora, IL, Fort Collins, CO, Naperville, IL, Rockford, IL, Elgin, IL, Greeley, CO, Green Bay, WI
Des Moines gardening questions
When is the last frost in Des Moines, IA?
Plan around Apr 24. At NOAA's Des Moines Int'l Airport, IA station, 3.5 mi from the city center, there is a 30% chance of a 32°F frost after that date. Half of springs have their last frost by Apr 18, and after May 2 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Apr 8. The last frost is fairly predictable here: only 28 days separate the 90% and 10% dates (median for cities on this site: 36 days).
When should I plant tomatoes in Des Moines, IA?
Start seeds indoors Feb 27 – Mar 13 and set transplants outside May 1 – May 15, once nights stay above 50°F and the soil is near 60°F. That leaves 173 days between the 30% frost dates, enough for most varieties including 80–85-day slicers. More: tomato planting dates by zone.
How long is the growing season in Des Moines?
About 184 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 165 days, and in 1 year in 10 it runs 203 days or more. In fall there is a 10% chance of frost by Oct 4 and a 30% chance by Oct 14. That is the longest of the 6 Iowa cities on this site.
When should I plant a fall garden in Des Moines?
Count back from the first fall frost (Oct 14): transplant broccoli Jul 22 – Aug 5; sow kale Aug 5 – Sep 2; sow lettuce Aug 5 – Sep 2; sow radishes Sep 2 – Sep 30. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Oct 30. How the math works: succession and fall planting.
Did Des Moines's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, Des Moines is zone 5b on both the 2012 and the 2023 USDA maps (PRISM/OSU ZIP listings). About 42% of U.S. ZIP codes kept their half-zone in 2023. Why the 2023 map is warmer.
How does Des Moines compare with Ankeny, IA?
Both are in zone 5b. The typical last spring frost in Des Moines (Apr 24) comes about 5 days earlier than in Ankeny, IA (Apr 29), 11 miles away, and the first fall frost is Oct 14 versus Oct 9. Des Moines sits about 186 ft lower, which explains part of the gap. The two cities use different NOAA stations.