Winterset, IA frost dates
Last spring frostApr 30median date
First fall frostOct 3median date
Growing season156 daysfrost-free
Hardiness zone5bZone 5b
How Winterset compares
- In 8 years out of 10, the last spring frost in Winterset falls between April 17 and May 11, a 24-day window. The first fall frost falls between September 20 and October 20.
- The median last frost is 2 days later than the Iowa median of Apr 28.
- Its 156-day growing season is longer than 15% 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 145 nights a year at or below 32°F.
- Compared with West Des Moines, IA, 33 km away, the last frost here is 12 days later than there and the growing season is 29 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 17 |
| 50% (median) | April 30 |
| 10% (safe for tender plants) | May 11 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 20 |
| 50% (median) | October 3 |
| 90% (late) | October 20 |
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 Winterset, IA
Winterset, IA frost dates — last frost Apr 30, first frost Oct 3, zone 5b. whenisthelastfrost.com
Crop
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Start indoors: Feb 5 to Feb 19Transplant outside: Apr 2 to Apr 16
Start indoors: Feb 19 to Mar 5Transplant outside: May 14 to May 28
Start indoors: Feb 19 to Mar 5Transplant outside: May 14 to May 28
Start indoors: Mar 5 to Mar 19Transplant outside: May 7 to May 21
Start indoors: Mar 5 to Mar 19Transplant outside: Apr 9 to Apr 23Sow outdoors: Apr 2 to May 7Plant for fall: Aug 8 to Sep 5
Start indoors: Mar 5 to Mar 19Transplant outside: Apr 2 to Apr 16Sow outdoors: Apr 2 to Apr 16Plant for fall: Jul 25 to Aug 15
Start indoors: Mar 5 to Mar 19Transplant outside: Apr 16 to Apr 30Plant for fall: Jun 27 to Jul 18
Start indoors: Mar 5 to Mar 19Transplant outside: Apr 9 to Apr 23Plant for fall: Jun 27 to Jul 18
Start indoors: Mar 5 to Mar 19Transplant outside: Apr 16 to Apr 30Plant for fall: Jun 27 to Jul 18
Start indoors: Mar 19 to Apr 2Transplant outside: May 21 to Jun 4Sow outdoors: May 21 to Jun 4
Start indoors: Mar 19 to Apr 2Transplant outside: May 7 to May 21
Sow outdoors: Mar 19 to Apr 9Plant for fall: Jul 11 to Aug 1
Sow outdoors: Mar 19 to Apr 9Plant for fall: Aug 8 to Aug 29
Sow outdoors: Mar 26 to May 7Plant for fall: Aug 22 to Sep 12
Start indoors: Apr 2 to Apr 9Transplant outside: May 14 to May 21Sow outdoors: May 7 to May 21Plant for fall: Jul 18 to Aug 1
Start indoors: Apr 2 to Apr 9Sow outdoors: May 7 to May 21Plant for fall: Jul 25 to Aug 8
Start indoors: Apr 2 to Apr 9Sow outdoors: May 7 to May 21
Start indoors: Apr 2 to Apr 9Transplant outside: May 14 to May 28
Sow outdoors: Apr 9 to May 7Plant for fall: Jul 11 to Jul 25
Sow outdoors: Apr 9 to May 7Plant for fall: Jul 25 to Aug 8
Sow outdoors: Apr 9 to Apr 30
Sow outdoors: Apr 16 to May 14Plant for fall: Jul 25 to Aug 8
Sow outdoors: Apr 16 to May 7Plant for fall: Aug 8 to Aug 29
Sow outdoors: May 7 to May 28Plant for fall: Jul 18 to Aug 1
Sow outdoors: May 7 to May 21
Transplant outside: May 14 to Jun 4
Plant for fall: Sep 19 to Oct 24
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Winterset, IA
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 5 – Feb 19 | Apr 2 – Apr 16 | — | — |
| Peppers | Feb 19 – Mar 5 | May 14 – May 28 | — | — |
| Eggplant | Feb 19 – Mar 5 | May 14 – May 28 | — | — |
| Tomatoes | Mar 5 – Mar 19 | May 7 – May 21 | — | — |
| Lettuce | Mar 5 – Mar 19 | Apr 9 – Apr 23 | Apr 2 – May 7 | Aug 8 – Sep 5 |
| Kale | Mar 5 – Mar 19 | Apr 2 – Apr 16 | Apr 2 – Apr 16 | Jul 25 – Aug 15 |
| Broccoli | Mar 5 – Mar 19 | Apr 16 – Apr 30 | — | Jun 27 – Jul 18 |
| Cabbage | Mar 5 – Mar 19 | Apr 9 – Apr 23 | — | Jun 27 – Jul 18 |
| Cauliflower | Mar 5 – Mar 19 | Apr 16 – Apr 30 | — | Jun 27 – Jul 18 |
| Okra | Mar 19 – Apr 2 | May 21 – Jun 4 | May 21 – Jun 4 | — |
| Basil | Mar 19 – Apr 2 | May 7 – May 21 | — | — |
| Peas | — | — | Mar 19 – Apr 9 | Jul 11 – Aug 1 |
| Spinach | — | — | Mar 19 – Apr 9 | Aug 8 – Aug 29 |
| Radishes | — | — | Mar 26 – May 7 | Aug 22 – Sep 12 |
| Cucumbers | Apr 2 – Apr 9 | May 14 – May 21 | May 7 – May 21 | Jul 18 – Aug 1 |
| Zucchini & Summer Squash | Apr 2 – Apr 9 | — | May 7 – May 21 | Jul 25 – Aug 8 |
| Winter Squash & Pumpkins | Apr 2 – Apr 9 | — | May 7 – May 21 | — |
| Melons & Watermelon | Apr 2 – Apr 9 | May 14 – May 28 | — | — |
| Carrots | — | — | Apr 9 – May 7 | Jul 11 – Jul 25 |
| Beets | — | — | Apr 9 – May 7 | Jul 25 – Aug 8 |
| Potatoes | — | — | Apr 9 – Apr 30 | — |
| Swiss Chard | — | — | Apr 16 – May 14 | Jul 25 – Aug 8 |
| Cilantro | — | — | Apr 16 – May 7 | Aug 8 – Aug 29 |
| Green Beans | — | — | May 7 – May 28 | Jul 18 – Aug 1 |
| Sweet Corn | — | — | May 7 – May 21 | — |
| Sweet Potatoes | — | May 14 – Jun 4 | — | — |
| Garlic | — | — | — | Sep 19 – Oct 24 |
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 Winterset 1s, IA weather station, 3 km away (elevation 1,099 ft (335 m)).
Frost dates near Winterset
- Patterson Apr 30 · Oct 3
- Peru Apr 30 · Oct 3
- Saint Charles Apr 30 · Oct 3
- Van Meter Apr 30 · Oct 3
- Earlham Apr 30 · Oct 3
- Bevington Apr 24 · Oct 12
- Truro Apr 30 · Oct 3
- De Soto Apr 30 · Oct 3
- Macksburg Apr 30 · Oct 3
- Saint Marys Apr 24 · Oct 12
Frequently asked questions
When is the last frost in Winterset, IA?
The median last spring frost in Winterset, IA is April 30. There is still about a 10% chance of frost after May 11, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Winterset, IA?
The median first fall frost is October 3, with about a 10% chance of frost before September 20.
How long is the growing season in Winterset, IA?
About 156 days between the median last spring frost and first fall frost.
What planting zone is Winterset, IA?
Winterset, IA is in USDA hardiness zone 5b.