Cedar Rapids, Iowa: planting zone & frost dates
Cedar Rapids is in USDA plant hardiness zone 5a, where the average coldest winter night reaches -20 to -15°F (-28.9 to -26.1°C). The typical last spring frost is around May 3 and the first fall frost around Oct 5.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | May 11 | Sep 25 |
| Typical planning date (30% risk) | May 3 | Oct 5 |
| Median (50%) | Apr 27 | Oct 11 |
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 CEDAR RAPIDS MUNI AP, IA (USW00014990), 5.9 mi (9.5 km) from the city center and 135 ft higher than the city center (+41 m). Record used for the 1991–2020 normals: 30 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Cedar Rapids
Cedar Rapids spans more than one half-zone. Share of the city's land area by zone (via its 7 ZIP codes): 5a (66%), 5b (34%). The headline zone is the one covering the most land. Look up your ZIP for your exact zone.
Vegetable planting calendar for Cedar Rapids
Dates are counted from the 30%-risk frost dates above (last frost May 3, first frost Oct 5). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Mar 8 – Mar 22 | May 10 – May 24 | — | — |
| Pepper | Feb 22 – Mar 8 | May 17 – May 31 | — | — |
| Lettuce | Mar 22 – Apr 5 | Apr 19 – May 10 | Apr 5 – May 17 | Jul 27 – Aug 24 |
| Green Beans | — | — | May 10 – Jun 14 | Jul 13 – Jul 27 |
| Sweet Corn | — | — | May 10 – Jun 7 | — |
| Zucchini & Summer Squash | Apr 5 – Apr 12 | May 10 – May 24 | May 10 – May 31 | Jul 13 – Jul 27 |
| Cucumber | Apr 5 – Apr 12 | May 17 – May 24 | May 10 – May 31 | Jul 13 – Jul 27 |
| Carrot | — | — | Apr 12 – May 17 | Jul 13 – Jul 27 |
| Onion | Feb 8 – Feb 22 | Apr 5 – Apr 19 | — | — |
| Potato | — | Apr 5 – Apr 26 | — | — |
| Basil | Mar 22 – Apr 5 | May 17 – May 31 | May 17 – Jun 7 | — |
| Spinach | — | — | Mar 22 – Apr 19 | Aug 10 – Sep 7 |
| Kale | Mar 8 – Mar 22 | Apr 5 – Apr 26 | Apr 5 – Apr 26 | Jul 27 – Aug 24 |
| Broccoli | Mar 8 – Mar 22 | Apr 19 – May 10 | — | Jul 13 – Jul 27 |
| Peas | — | — | Mar 22 – Apr 12 | Jul 27 – Aug 10 |
| Eggplant | Feb 22 – Mar 8 | May 17 – May 31 | — | — |
| Cabbage | Mar 8 – Mar 22 | Apr 5 – Apr 19 | — | Jul 13 – Jul 27 |
| Radish | — | — | Mar 29 – May 17 | Aug 24 – Sep 21 |
| Strawberry | — | Apr 5 – Apr 26 | — | — |
| Beets | — | — | Apr 12 – May 24 | Jul 27 – Aug 10 |
Nearby cities in Iowa
- Iowa City — zone 5b, last frost Apr 28, first frost Oct 13
- Davenport — zone 5b, last frost Apr 24, first frost Oct 17
- Ankeny — zone 5b, last frost Apr 29, first frost Oct 9
- Des Moines — zone 5b, last frost Apr 24, first frost Oct 14
- Sioux City — zone 5a, last frost May 4, first frost Oct 1
More: all Iowa cities · other zone 5a cities: Minneapolis, MN, St. Paul, MN, Anchorage, AK, Sioux Falls, SD, Billings, MT, Bloomington, MN, Sioux City, IA, Brooklyn Park, MN
Cedar Rapids gardening questions
When is the last frost in Cedar Rapids, IA?
Plan around May 3. At NOAA's Cedar Rapids Municipal Airport, IA station, 5.9 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 27, and after May 11 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Apr 16. 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 Cedar Rapids, IA?
Start seeds indoors Mar 8 – Mar 22 and set transplants outside May 10 – May 24, once nights stay above 50°F and the soil is near 60°F. That leaves 155 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 Cedar Rapids?
About 165 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 146 days, and in 1 year in 10 it runs 184 days or more. In fall there is a 10% chance of frost by Sep 25 and a 30% chance by Oct 5. That ranks 5th longest of 6 Iowa cities on this site.
When should I plant a fall garden in Cedar Rapids?
Count back from the first fall frost (Oct 5): transplant broccoli Jul 13 – Jul 27; sow kale Jul 27 – Aug 24; sow lettuce Jul 27 – Aug 24; sow radishes Aug 24 – Sep 21. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Oct 21. How the math works: succession and fall planting.
Did Cedar Rapids's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, Cedar Rapids is zone 5a 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.
Is all of Cedar Rapids in zone 5a?
No. Zone 5a covers about 66% of the city's land; the rest is in 5b (34%), measured across the city's 7 ZIP codes. Check your own ZIP code in the table above or with the ZIP lookup.