Afton, WI frost dates
Last spring frostApr 26median date
First fall frostOct 15median date
Growing season172 daysfrost-free
Hardiness zone5bZone 5b
How Afton compares
- In 8 years out of 10, the last spring frost in Afton falls between April 13 and May 11, a 28-day window. The first fall frost falls between October 1 and October 27.
- The median last frost is 9 days earlier than the Wisconsin median of May 5.
- Its 172-day growing season is longer than 89% of the 749 Wisconsin places with a regular frost season (state median 155 days).
- The last frost is 5 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.
- Afton shares its weather station with Janesville, WI, 11 km away, so the two have the same frost dates.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 13 |
| 50% (median) | April 26 |
| 10% (safe for tender plants) | May 11 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 1 |
| 50% (median) | October 15 |
| 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 Afton, WI
Afton, WI frost dates — last frost Apr 26, first frost Oct 15, zone 5b. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Feb 1 to Feb 15Transplant outside: Mar 29 to Apr 12
Start indoors: Feb 15 to Mar 1Transplant outside: May 10 to May 24
Start indoors: Feb 15 to Mar 1Transplant outside: May 10 to May 24
Start indoors: Mar 1 to Mar 15Transplant outside: May 3 to May 17
Start indoors: Mar 1 to Mar 15Transplant outside: Apr 5 to Apr 19Sow outdoors: Mar 29 to May 3Plant for fall: Aug 20 to Sep 17
Start indoors: Mar 1 to Mar 15Transplant outside: Mar 29 to Apr 12Sow outdoors: Mar 29 to Apr 12Plant for fall: Aug 6 to Aug 27
Start indoors: Mar 1 to Mar 15Transplant outside: Apr 12 to Apr 26Plant for fall: Jul 9 to Jul 30
Start indoors: Mar 1 to Mar 15Transplant outside: Apr 5 to Apr 19Plant for fall: Jul 9 to Jul 30
Start indoors: Mar 1 to Mar 15Transplant outside: Apr 12 to Apr 26Plant for fall: Jul 9 to Jul 30
Start indoors: Mar 15 to Mar 29Transplant outside: May 17 to May 31Sow outdoors: May 17 to May 31
Start indoors: Mar 15 to Mar 29Transplant outside: May 3 to May 17
Sow outdoors: Mar 15 to Apr 5Plant for fall: Jul 23 to Aug 13
Sow outdoors: Mar 15 to Apr 5Plant for fall: Aug 20 to Sep 10
Sow outdoors: Mar 22 to May 3Plant for fall: Sep 3 to Sep 24
Start indoors: Mar 29 to Apr 5Transplant outside: May 10 to May 17Sow outdoors: May 3 to May 17Plant for fall: Jul 30 to Aug 13
Start indoors: Mar 29 to Apr 5Sow outdoors: May 3 to May 17Plant for fall: Aug 6 to Aug 20
Start indoors: Mar 29 to Apr 5Sow outdoors: May 3 to May 17
Start indoors: Mar 29 to Apr 5Transplant outside: May 10 to May 24
Sow outdoors: Apr 5 to May 3Plant for fall: Jul 23 to Aug 6
Sow outdoors: Apr 5 to May 3Plant for fall: Aug 6 to Aug 20
Sow outdoors: Apr 5 to Apr 26
Sow outdoors: Apr 12 to May 10Plant for fall: Aug 6 to Aug 20
Sow outdoors: Apr 12 to May 3Plant for fall: Aug 20 to Sep 10
Sow outdoors: May 3 to May 24Plant for fall: Jul 30 to Aug 13
Sow outdoors: May 3 to May 17
Transplant outside: May 10 to May 31
Plant for fall: Oct 1 to Nov 5
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Afton, WI
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 1 – Feb 15 | Mar 29 – Apr 12 | — | — |
| Peppers | Feb 15 – Mar 1 | May 10 – May 24 | — | — |
| Eggplant | Feb 15 – Mar 1 | May 10 – May 24 | — | — |
| Tomatoes | Mar 1 – Mar 15 | May 3 – May 17 | — | — |
| Lettuce | Mar 1 – Mar 15 | Apr 5 – Apr 19 | Mar 29 – May 3 | Aug 20 – Sep 17 |
| Kale | Mar 1 – Mar 15 | Mar 29 – Apr 12 | Mar 29 – Apr 12 | Aug 6 – Aug 27 |
| Broccoli | Mar 1 – Mar 15 | Apr 12 – Apr 26 | — | Jul 9 – Jul 30 |
| Cabbage | Mar 1 – Mar 15 | Apr 5 – Apr 19 | — | Jul 9 – Jul 30 |
| Cauliflower | Mar 1 – Mar 15 | Apr 12 – Apr 26 | — | Jul 9 – Jul 30 |
| Okra | Mar 15 – Mar 29 | May 17 – May 31 | May 17 – May 31 | — |
| Basil | Mar 15 – Mar 29 | May 3 – May 17 | — | — |
| Peas | — | — | Mar 15 – Apr 5 | Jul 23 – Aug 13 |
| Spinach | — | — | Mar 15 – Apr 5 | Aug 20 – Sep 10 |
| Radishes | — | — | Mar 22 – May 3 | Sep 3 – Sep 24 |
| Cucumbers | Mar 29 – Apr 5 | May 10 – May 17 | May 3 – May 17 | Jul 30 – Aug 13 |
| Zucchini & Summer Squash | Mar 29 – Apr 5 | — | May 3 – May 17 | Aug 6 – Aug 20 |
| Winter Squash & Pumpkins | Mar 29 – Apr 5 | — | May 3 – May 17 | — |
| Melons & Watermelon | Mar 29 – Apr 5 | May 10 – May 24 | — | — |
| Carrots | — | — | Apr 5 – May 3 | Jul 23 – Aug 6 |
| Beets | — | — | Apr 5 – May 3 | Aug 6 – Aug 20 |
| Potatoes | — | — | Apr 5 – Apr 26 | — |
| Swiss Chard | — | — | Apr 12 – May 10 | Aug 6 – Aug 20 |
| Cilantro | — | — | Apr 12 – May 3 | Aug 20 – Sep 10 |
| Green Beans | — | — | May 3 – May 24 | Jul 30 – Aug 13 |
| Sweet Corn | — | — | May 3 – May 17 | — |
| Sweet Potatoes | — | May 10 – May 31 | — | — |
| Garlic | — | — | — | Oct 1 – Nov 5 |
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 Afton - Janesville Wwtp, WI weather station, 4 km away (elevation 761 ft (232 m)).
Frost dates near Afton
- Beloit May 1 · Oct 12
- Hanover Apr 26 · Oct 15
- Janesville Apr 26 · Oct 15
- Footville Apr 26 · Oct 15
- Orfordville Apr 29 · Oct 12
- Clinton Apr 30 · Oct 10
- Avalon Apr 30 · Oct 10
- Milton Apr 28 · Oct 13
- Brodhead Apr 29 · Oct 12
- Evansville Apr 30 · Oct 11
Frequently asked questions
When is the last frost in Afton, WI?
The median last spring frost in Afton, WI is April 26. 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 Afton, WI?
The median first fall frost is October 15, with about a 10% chance of frost before October 1.
How long is the growing season in Afton, WI?
About 172 days between the median last spring frost and first fall frost.
What planting zone is Afton, WI?
Afton, WI is in USDA hardiness zone 5b.