Griswold, IA frost dates
Last spring frostApr 23median date
First fall frostOct 14median date
Growing season174 daysfrost-free
Hardiness zone5bZone 5b
How Griswold compares
- In 8 years out of 10, the last spring frost in Griswold falls between April 10 and May 5, a 25-day window. The first fall frost falls between September 30 and October 27.
- The median last frost is 5 days earlier than the Iowa median of Apr 28.
- Its 174-day growing season is longer than 78% 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 148 nights a year at or below 32°F.
- Compared with Council Bluffs, IA, 60 km away, the last frost here is 5 days later than there and the growing season is 12 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 10 |
| 50% (median) | April 23 |
| 10% (safe for tender plants) | May 5 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 30 |
| 50% (median) | October 14 |
| 90% (late) | October 27 |
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 Griswold, IA
Griswold, IA frost dates — last frost Apr 23, first frost Oct 14, 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 19 to Sep 16
Start indoors: Feb 26 to Mar 12Transplant outside: Mar 26 to Apr 9Sow outdoors: Mar 26 to Apr 9Plant for fall: Aug 5 to Aug 26
Start indoors: Feb 26 to Mar 12Transplant outside: Apr 9 to Apr 23Plant for fall: Jul 8 to Jul 29
Start indoors: Feb 26 to Mar 12Transplant outside: Apr 2 to Apr 16Plant for fall: Jul 8 to Jul 29
Start indoors: Feb 26 to Mar 12Transplant outside: Apr 9 to Apr 23Plant for fall: Jul 8 to Jul 29
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 22 to Aug 12
Sow outdoors: Mar 12 to Apr 2Plant for fall: Aug 19 to Sep 9
Sow outdoors: Mar 19 to Apr 30Plant for fall: Sep 2 to Sep 23
Start indoors: Mar 26 to Apr 2Transplant outside: May 7 to May 14Sow outdoors: Apr 30 to May 14Plant for fall: Jul 29 to Aug 12
Start indoors: Mar 26 to Apr 2Sow outdoors: Apr 30 to May 14Plant for fall: Aug 5 to Aug 19
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 22 to Aug 5
Sow outdoors: Apr 2 to Apr 30Plant for fall: Aug 5 to Aug 19
Sow outdoors: Apr 2 to Apr 23
Sow outdoors: Apr 9 to May 7Plant for fall: Aug 5 to Aug 19
Sow outdoors: Apr 9 to Apr 30Plant for fall: Aug 19 to Sep 9
Sow outdoors: Apr 30 to May 21Plant for fall: Jul 29 to Aug 12
Sow outdoors: Apr 30 to May 14
Transplant outside: May 7 to May 28
Plant for fall: Sep 30 to Nov 4
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Griswold, 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 19 – Sep 16 |
| Kale | Feb 26 – Mar 12 | Mar 26 – Apr 9 | Mar 26 – Apr 9 | Aug 5 – Aug 26 |
| Broccoli | Feb 26 – Mar 12 | Apr 9 – Apr 23 | — | Jul 8 – Jul 29 |
| Cabbage | Feb 26 – Mar 12 | Apr 2 – Apr 16 | — | Jul 8 – Jul 29 |
| Cauliflower | Feb 26 – Mar 12 | Apr 9 – Apr 23 | — | Jul 8 – Jul 29 |
| 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 22 – Aug 12 |
| Spinach | — | — | Mar 12 – Apr 2 | Aug 19 – Sep 9 |
| Radishes | — | — | Mar 19 – Apr 30 | Sep 2 – Sep 23 |
| Cucumbers | Mar 26 – Apr 2 | May 7 – May 14 | Apr 30 – May 14 | Jul 29 – Aug 12 |
| Zucchini & Summer Squash | Mar 26 – Apr 2 | — | Apr 30 – May 14 | Aug 5 – Aug 19 |
| 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 22 – Aug 5 |
| Beets | — | — | Apr 2 – Apr 30 | Aug 5 – Aug 19 |
| Potatoes | — | — | Apr 2 – Apr 23 | — |
| Swiss Chard | — | — | Apr 9 – May 7 | Aug 5 – Aug 19 |
| Cilantro | — | — | Apr 9 – Apr 30 | Aug 19 – Sep 9 |
| Green Beans | — | — | Apr 30 – May 21 | Jul 29 – Aug 12 |
| Sweet Corn | — | — | Apr 30 – May 14 | — |
| Sweet Potatoes | — | May 7 – May 28 | — | — |
| Garlic | — | — | — | Sep 30 – Nov 4 |
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 Oakland, IA weather station, 22 km away (elevation 1,260 ft (384 m)).
Frost dates near Griswold
- Lewis Apr 30 · Oct 2
- Elliott Apr 24 · Oct 13
- Grant Apr 27 · Oct 12
- Atlantic Apr 30 · Oct 2
- Oakland Apr 23 · Oct 14
- Cumberland Apr 30 · Oct 2
- Carson Apr 23 · Oct 14
- Hancock Apr 23 · Oct 14
- Red Oak Apr 24 · Oct 13
- Marne Apr 30 · Oct 2
Frequently asked questions
When is the last frost in Griswold, IA?
The median last spring frost in Griswold, IA is April 23. There is still about a 10% chance of frost after May 5, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Griswold, IA?
The median first fall frost is October 14, with about a 10% chance of frost before September 30.
How long is the growing season in Griswold, IA?
About 174 days between the median last spring frost and first fall frost.
What planting zone is Griswold, IA?
Griswold, IA is in USDA hardiness zone 5b.