Thayer, IA frost dates
Last spring frostApr 23median date
First fall frostOct 17median date
Growing season177 daysfrost-free
Hardiness zone5bZone 5b
How Thayer compares
- In 8 years out of 10, the last spring frost in Thayer falls between April 7 and May 6, a 29-day window. The first fall frost falls between October 1 and October 31.
- The median last frost is 5 days earlier than the Iowa median of Apr 28.
- Its 177-day growing season is longer than 84% of the 934 Iowa places with a regular frost season (state median 165 days).
- The last frost is 8 days earlier than the zone 5b median of May 1. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 5b chart.
- The weather station records an average of 142 nights a year at or below 32°F.
- Compared with West Des Moines, IA, 68 km away, the last frost here is 5 days later than there and the growing season is 8 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 7 |
| 50% (median) | April 23 |
| 10% (safe for tender plants) | May 6 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 1 |
| 50% (median) | October 17 |
| 90% (late) | October 31 |
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 Thayer, IA
Thayer, IA frost dates — last frost Apr 23, first frost Oct 17, zone 5b. whenisthelastfrost.com
Crop
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Start indoors: Jan 29 to Feb 12Transplant outside: Mar 26 to Apr 9
Start indoors: Feb 12 to Feb 26Transplant outside: May 7 to May 21
Start indoors: Feb 12 to Feb 26Transplant outside: May 7 to May 21
Start indoors: Feb 26 to Mar 12Transplant outside: Apr 30 to May 14
Start indoors: Feb 26 to Mar 12Transplant outside: Apr 2 to Apr 16Sow outdoors: Mar 26 to Apr 30Plant for fall: Aug 22 to Sep 19
Start indoors: Feb 26 to Mar 12Transplant outside: Mar 26 to Apr 9Sow outdoors: Mar 26 to Apr 9Plant for fall: Aug 8 to Aug 29
Start indoors: Feb 26 to Mar 12Transplant outside: Apr 9 to Apr 23Plant for fall: Jul 11 to Aug 1
Start indoors: Feb 26 to Mar 12Transplant outside: Apr 2 to Apr 16Plant for fall: Jul 11 to Aug 1
Start indoors: Feb 26 to Mar 12Transplant outside: Apr 9 to Apr 23Plant for fall: Jul 11 to Aug 1
Start indoors: Mar 12 to Mar 26Transplant outside: May 14 to May 28Sow outdoors: May 14 to May 28
Start indoors: Mar 12 to Mar 26Transplant outside: Apr 30 to May 14
Sow outdoors: Mar 12 to Apr 2Plant for fall: Jul 25 to Aug 15
Sow outdoors: Mar 12 to Apr 2Plant for fall: Aug 22 to Sep 12
Sow outdoors: Mar 19 to Apr 30Plant for fall: Sep 5 to Sep 26
Start indoors: Mar 26 to Apr 2Transplant outside: May 7 to May 14Sow outdoors: Apr 30 to May 14Plant for fall: Aug 1 to Aug 15
Start indoors: Mar 26 to Apr 2Sow outdoors: Apr 30 to May 14Plant for fall: Aug 8 to Aug 22
Start indoors: Mar 26 to Apr 2Sow outdoors: Apr 30 to May 14
Start indoors: Mar 26 to Apr 2Transplant outside: May 7 to May 21
Sow outdoors: Apr 2 to Apr 30Plant for fall: Jul 25 to Aug 8
Sow outdoors: Apr 2 to Apr 30Plant for fall: Aug 8 to Aug 22
Sow outdoors: Apr 2 to Apr 23
Sow outdoors: Apr 9 to May 7Plant for fall: Aug 8 to Aug 22
Sow outdoors: Apr 9 to Apr 30Plant for fall: Aug 22 to Sep 12
Sow outdoors: Apr 30 to May 21Plant for fall: Aug 1 to Aug 15
Sow outdoors: Apr 30 to May 14
Transplant outside: May 7 to May 28
Plant for fall: Oct 3 to Nov 7
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Thayer, IA
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Jan 29 – Feb 12 | Mar 26 – Apr 9 | — | — |
| Peppers | Feb 12 – Feb 26 | May 7 – May 21 | — | — |
| Eggplant | Feb 12 – Feb 26 | May 7 – May 21 | — | — |
| Tomatoes | Feb 26 – Mar 12 | Apr 30 – May 14 | — | — |
| Lettuce | Feb 26 – Mar 12 | Apr 2 – Apr 16 | Mar 26 – Apr 30 | Aug 22 – Sep 19 |
| Kale | Feb 26 – Mar 12 | Mar 26 – Apr 9 | Mar 26 – Apr 9 | Aug 8 – Aug 29 |
| Broccoli | Feb 26 – Mar 12 | Apr 9 – Apr 23 | — | Jul 11 – Aug 1 |
| Cabbage | Feb 26 – Mar 12 | Apr 2 – Apr 16 | — | Jul 11 – Aug 1 |
| Cauliflower | Feb 26 – Mar 12 | Apr 9 – Apr 23 | — | Jul 11 – Aug 1 |
| Okra | Mar 12 – Mar 26 | May 14 – May 28 | May 14 – May 28 | — |
| Basil | Mar 12 – Mar 26 | Apr 30 – May 14 | — | — |
| Peas | — | — | Mar 12 – Apr 2 | Jul 25 – Aug 15 |
| Spinach | — | — | Mar 12 – Apr 2 | Aug 22 – Sep 12 |
| Radishes | — | — | Mar 19 – Apr 30 | Sep 5 – Sep 26 |
| Cucumbers | Mar 26 – Apr 2 | May 7 – May 14 | Apr 30 – May 14 | Aug 1 – Aug 15 |
| Zucchini & Summer Squash | Mar 26 – Apr 2 | — | Apr 30 – May 14 | Aug 8 – Aug 22 |
| Winter Squash & Pumpkins | Mar 26 – Apr 2 | — | Apr 30 – May 14 | — |
| Melons & Watermelon | Mar 26 – Apr 2 | May 7 – May 21 | — | — |
| Carrots | — | — | Apr 2 – Apr 30 | Jul 25 – Aug 8 |
| Beets | — | — | Apr 2 – Apr 30 | Aug 8 – Aug 22 |
| Potatoes | — | — | Apr 2 – Apr 23 | — |
| Swiss Chard | — | — | Apr 9 – May 7 | Aug 8 – Aug 22 |
| Cilantro | — | — | Apr 9 – Apr 30 | Aug 22 – Sep 12 |
| Green Beans | — | — | Apr 30 – May 21 | Aug 1 – Aug 15 |
| Sweet Corn | — | — | Apr 30 – May 14 | — |
| Sweet Potatoes | — | May 7 – May 28 | — | — |
| Garlic | — | — | — | Oct 3 – Nov 7 |
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 Beaconsfield, IA weather station, 22 km away (elevation 1,214 ft (370 m)).
Frost dates near Thayer
- Murray Apr 29 · Oct 9
- Afton Apr 28 · Oct 11
- Lorimor Apr 30 · Oct 3
- Arispe Apr 28 · Oct 11
- Ellston Apr 23 · Oct 17
- Tingley Apr 23 · Oct 17
- Shannon City Apr 28 · Oct 11
- Grand River Apr 23 · Oct 17
- Creston Apr 28 · Oct 11
- Macksburg Apr 30 · Oct 3
Frequently asked questions
When is the last frost in Thayer, IA?
The median last spring frost in Thayer, IA is April 23. There is still about a 10% chance of frost after May 6, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Thayer, IA?
The median first fall frost is October 17, with about a 10% chance of frost before October 1.
How long is the growing season in Thayer, IA?
About 177 days between the median last spring frost and first fall frost.
What planting zone is Thayer, IA?
Thayer, IA is in USDA hardiness zone 5b.