Frost dates for 52240 — Iowa City, IA
Last spring frostApr 29median date
First fall frostOct 9median date
Growing season163 daysfrost-free
Hardiness zone5bZone 5b
How Iowa City compares
- In 8 years out of 10, the last spring frost in Iowa City falls between April 14 and May 14, a 30-day window. The first fall frost falls between September 25 and October 22.
- The median last frost is 1 day later than the Iowa median of Apr 28.
- Its 163-day growing season is longer than 35% of the 934 Iowa places with a regular frost season (state median 165 days).
- The last frost is typical for zone 5b, where the median is May 1.
- The weather station records an average of 130 nights a year at or below 32°F.
- Compared with Cedar Rapids, IA, 46 km away, the last frost here is 1 day later than there and the growing season is 4 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 14 |
| 50% (median) | April 29 |
| 10% (safe for tender plants) | May 14 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 25 |
| 50% (median) | October 9 |
| 90% (late) | October 22 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Iowa City, IA
Frost dates for 52240 — Iowa City, IA — last frost Apr 29, first frost Oct 9, zone 5b. whenisthelastfrost.com
Crop
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Start indoors: Feb 4 to Feb 18Transplant outside: Apr 1 to Apr 15
Start indoors: Feb 18 to Mar 4Transplant outside: May 13 to May 27
Start indoors: Feb 18 to Mar 4Transplant outside: May 13 to May 27
Start indoors: Mar 4 to Mar 18Transplant outside: May 6 to May 20
Start indoors: Mar 4 to Mar 18Transplant outside: Apr 8 to Apr 22Sow outdoors: Apr 1 to May 6Plant for fall: Aug 14 to Sep 11
Start indoors: Mar 4 to Mar 18Transplant outside: Apr 1 to Apr 15Sow outdoors: Apr 1 to Apr 15Plant for fall: Jul 31 to Aug 21
Start indoors: Mar 4 to Mar 18Transplant outside: Apr 15 to Apr 29Plant for fall: Jul 3 to Jul 24
Start indoors: Mar 4 to Mar 18Transplant outside: Apr 8 to Apr 22Plant for fall: Jul 3 to Jul 24
Start indoors: Mar 4 to Mar 18Transplant outside: Apr 15 to Apr 29Plant for fall: Jul 3 to Jul 24
Start indoors: Mar 18 to Apr 1Transplant outside: May 20 to Jun 3Sow outdoors: May 20 to Jun 3
Start indoors: Mar 18 to Apr 1Transplant outside: May 6 to May 20
Sow outdoors: Mar 18 to Apr 8Plant for fall: Jul 17 to Aug 7
Sow outdoors: Mar 18 to Apr 8Plant for fall: Aug 14 to Sep 4
Sow outdoors: Mar 25 to May 6Plant for fall: Aug 28 to Sep 18
Start indoors: Apr 1 to Apr 8Transplant outside: May 13 to May 20Sow outdoors: May 6 to May 20Plant for fall: Jul 24 to Aug 7
Start indoors: Apr 1 to Apr 8Sow outdoors: May 6 to May 20Plant for fall: Jul 31 to Aug 14
Start indoors: Apr 1 to Apr 8Sow outdoors: May 6 to May 20
Start indoors: Apr 1 to Apr 8Transplant outside: May 13 to May 27
Sow outdoors: Apr 8 to May 6Plant for fall: Jul 17 to Jul 31
Sow outdoors: Apr 8 to May 6Plant for fall: Jul 31 to Aug 14
Sow outdoors: Apr 8 to Apr 29
Sow outdoors: Apr 15 to May 13Plant for fall: Jul 31 to Aug 14
Sow outdoors: Apr 15 to May 6Plant for fall: Aug 14 to Sep 4
Sow outdoors: May 6 to May 27Plant for fall: Jul 24 to Aug 7
Sow outdoors: May 6 to May 20
Transplant outside: May 13 to Jun 3
Plant for fall: Sep 25 to Oct 30
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Iowa City, IA
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 4 – Feb 18 | Apr 1 – Apr 15 | — | — |
| Peppers | Feb 18 – Mar 4 | May 13 – May 27 | — | — |
| Eggplant | Feb 18 – Mar 4 | May 13 – May 27 | — | — |
| Tomatoes | Mar 4 – Mar 18 | May 6 – May 20 | — | — |
| Lettuce | Mar 4 – Mar 18 | Apr 8 – Apr 22 | Apr 1 – May 6 | Aug 14 – Sep 11 |
| Kale | Mar 4 – Mar 18 | Apr 1 – Apr 15 | Apr 1 – Apr 15 | Jul 31 – Aug 21 |
| Broccoli | Mar 4 – Mar 18 | Apr 15 – Apr 29 | — | Jul 3 – Jul 24 |
| Cabbage | Mar 4 – Mar 18 | Apr 8 – Apr 22 | — | Jul 3 – Jul 24 |
| Cauliflower | Mar 4 – Mar 18 | Apr 15 – Apr 29 | — | Jul 3 – Jul 24 |
| Okra | Mar 18 – Apr 1 | May 20 – Jun 3 | May 20 – Jun 3 | — |
| Basil | Mar 18 – Apr 1 | May 6 – May 20 | — | — |
| Peas | — | — | Mar 18 – Apr 8 | Jul 17 – Aug 7 |
| Spinach | — | — | Mar 18 – Apr 8 | Aug 14 – Sep 4 |
| Radishes | — | — | Mar 25 – May 6 | Aug 28 – Sep 18 |
| Cucumbers | Apr 1 – Apr 8 | May 13 – May 20 | May 6 – May 20 | Jul 24 – Aug 7 |
| Zucchini & Summer Squash | Apr 1 – Apr 8 | — | May 6 – May 20 | Jul 31 – Aug 14 |
| Winter Squash & Pumpkins | Apr 1 – Apr 8 | — | May 6 – May 20 | — |
| Melons & Watermelon | Apr 1 – Apr 8 | May 13 – May 27 | — | — |
| Carrots | — | — | Apr 8 – May 6 | Jul 17 – Jul 31 |
| Beets | — | — | Apr 8 – May 6 | Jul 31 – Aug 14 |
| Potatoes | — | — | Apr 8 – Apr 29 | — |
| Swiss Chard | — | — | Apr 15 – May 13 | Jul 31 – Aug 14 |
| Cilantro | — | — | Apr 15 – May 6 | Aug 14 – Sep 4 |
| Green Beans | — | — | May 6 – May 27 | Jul 24 – Aug 7 |
| Sweet Corn | — | — | May 6 – May 20 | — |
| Sweet Potatoes | — | May 13 – Jun 3 | — | — |
| Garlic | — | — | — | Sep 25 – Oct 30 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Iowa City, IA weather station, 3 km away (elevation 640 ft (195 m)).
ZIP codes in Iowa City: 52240 52242 52243 52244 52245 52246
Frost dates near Iowa City
- Hills Apr 29 · Oct 9
- Coralville Apr 21 · Oct 18
- North Liberty Apr 21 · Oct 18
- West Branch Apr 29 · Oct 9
- Lone Tree Apr 29 · Oct 9
- Tiffin Apr 21 · Oct 18
- Riverside Apr 29 · Oct 9
- Solon Apr 27 · Oct 11
Frequently asked questions
When is the last frost in Iowa City, IA?
The median last spring frost in Iowa City, IA is April 29. There is still about a 10% chance of frost after May 14, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Iowa City, IA?
The median first fall frost is October 9, with about a 10% chance of frost before September 25.
How long is the growing season in Iowa City, IA?
About 163 days between the median last spring frost and first fall frost.
What planting zone is Iowa City, IA?
Iowa City, IA is in USDA hardiness zone 5b.