Black Earth, WI frost dates
Last spring frostMay 7median date
First fall frostOct 1median date
Growing season147 daysfrost-free
Hardiness zone5aZone 5a
How Black Earth compares
- In 8 years out of 10, the last spring frost in Black Earth falls between April 22 and May 22, a 30-day window. The first fall frost falls between September 18 and October 16.
- The median last frost is 2 days later than the Wisconsin median of May 5.
- Its 147-day growing season is longer than 28% of the 749 Wisconsin places with a regular frost season (state median 155 days).
- The last frost is 4 days later than the zone 5a median of May 3. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 5a chart.
- The weather station records an average of 156 nights a year at or below 32°F.
- Compared with Madison, WI, 28 km away, the last frost here is 6 days later than there and the growing season is 14 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 22 |
| 50% (median) | May 7 |
| 10% (safe for tender plants) | May 22 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 18 |
| 50% (median) | October 1 |
| 90% (late) | October 16 |
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 Black Earth, WI
Black Earth, WI frost dates — last frost May 7, first frost Oct 1, zone 5a. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Feb 12 to Feb 26Transplant outside: Apr 9 to Apr 23
Start indoors: Feb 26 to Mar 12Transplant outside: May 21 to Jun 4
Start indoors: Feb 26 to Mar 12Transplant outside: May 21 to Jun 4
Start indoors: Mar 12 to Mar 26Transplant outside: May 14 to May 28
Start indoors: Mar 12 to Mar 26Transplant outside: Apr 16 to Apr 30Sow outdoors: Apr 9 to May 14Plant for fall: Aug 6 to Sep 3
Start indoors: Mar 12 to Mar 26Transplant outside: Apr 9 to Apr 23Sow outdoors: Apr 9 to Apr 23Plant for fall: Jul 23 to Aug 13
Start indoors: Mar 12 to Mar 26Transplant outside: Apr 23 to May 7Plant for fall: Jun 25 to Jul 16
Start indoors: Mar 12 to Mar 26Transplant outside: Apr 16 to Apr 30Plant for fall: Jun 25 to Jul 16
Start indoors: Mar 12 to Mar 26Transplant outside: Apr 23 to May 7Plant for fall: Jun 25 to Jul 16
Start indoors: Mar 26 to Apr 9Transplant outside: May 28 to Jun 11Sow outdoors: May 28 to Jun 11
Start indoors: Mar 26 to Apr 9Transplant outside: May 14 to May 28
Sow outdoors: Mar 26 to Apr 16Plant for fall: Jul 9 to Jul 30
Sow outdoors: Mar 26 to Apr 16Plant for fall: Aug 6 to Aug 27
Sow outdoors: Apr 2 to May 14Plant for fall: Aug 20 to Sep 10
Start indoors: Apr 9 to Apr 16Transplant outside: May 21 to May 28Sow outdoors: May 14 to May 28Plant for fall: Jul 16 to Jul 30
Start indoors: Apr 9 to Apr 16Sow outdoors: May 14 to May 28Plant for fall: Jul 23 to Aug 6
Start indoors: Apr 9 to Apr 16Sow outdoors: May 14 to May 28
Start indoors: Apr 9 to Apr 16Transplant outside: May 21 to Jun 4
Sow outdoors: Apr 16 to May 14Plant for fall: Jul 9 to Jul 23
Sow outdoors: Apr 16 to May 14Plant for fall: Jul 23 to Aug 6
Sow outdoors: Apr 16 to May 7
Sow outdoors: Apr 23 to May 21Plant for fall: Jul 23 to Aug 6
Sow outdoors: Apr 23 to May 14Plant for fall: Aug 6 to Aug 27
Sow outdoors: May 14 to Jun 4Plant for fall: Jul 16 to Jul 30
Sow outdoors: May 14 to May 28
Transplant outside: May 21 to Jun 11
Plant for fall: Sep 17 to Oct 22
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Black Earth, WI
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 12 – Feb 26 | Apr 9 – Apr 23 | — | — |
| Peppers | Feb 26 – Mar 12 | May 21 – Jun 4 | — | — |
| Eggplant | Feb 26 – Mar 12 | May 21 – Jun 4 | — | — |
| Tomatoes | Mar 12 – Mar 26 | May 14 – May 28 | — | — |
| Lettuce | Mar 12 – Mar 26 | Apr 16 – Apr 30 | Apr 9 – May 14 | Aug 6 – Sep 3 |
| Kale | Mar 12 – Mar 26 | Apr 9 – Apr 23 | Apr 9 – Apr 23 | Jul 23 – Aug 13 |
| Broccoli | Mar 12 – Mar 26 | Apr 23 – May 7 | — | Jun 25 – Jul 16 |
| Cabbage | Mar 12 – Mar 26 | Apr 16 – Apr 30 | — | Jun 25 – Jul 16 |
| Cauliflower | Mar 12 – Mar 26 | Apr 23 – May 7 | — | Jun 25 – Jul 16 |
| Okra | Mar 26 – Apr 9 | May 28 – Jun 11 | May 28 – Jun 11 | — |
| Basil | Mar 26 – Apr 9 | May 14 – May 28 | — | — |
| Peas | — | — | Mar 26 – Apr 16 | Jul 9 – Jul 30 |
| Spinach | — | — | Mar 26 – Apr 16 | Aug 6 – Aug 27 |
| Radishes | — | — | Apr 2 – May 14 | Aug 20 – Sep 10 |
| Cucumbers | Apr 9 – Apr 16 | May 21 – May 28 | May 14 – May 28 | Jul 16 – Jul 30 |
| Zucchini & Summer Squash | Apr 9 – Apr 16 | — | May 14 – May 28 | Jul 23 – Aug 6 |
| Winter Squash & Pumpkins | Apr 9 – Apr 16 | — | May 14 – May 28 | — |
| Melons & Watermelon | Apr 9 – Apr 16 | May 21 – Jun 4 | — | — |
| Carrots | — | — | Apr 16 – May 14 | Jul 9 – Jul 23 |
| Beets | — | — | Apr 16 – May 14 | Jul 23 – Aug 6 |
| Potatoes | — | — | Apr 16 – May 7 | — |
| Swiss Chard | — | — | Apr 23 – May 21 | Jul 23 – Aug 6 |
| Cilantro | — | — | Apr 23 – May 14 | Aug 6 – Aug 27 |
| Green Beans | — | — | May 14 – Jun 4 | Jul 16 – Jul 30 |
| Sweet Corn | — | — | May 14 – May 28 | — |
| Sweet Potatoes | — | May 21 – Jun 11 | — | — |
| Garlic | — | — | — | Sep 17 – Oct 22 |
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 Mazomanie Wwtp, WI weather station, 8 km away (elevation 764 ft (233 m)).
Frost dates near Black Earth
- Mazomanie May 7 · Oct 1
- Cross Plains Apr 28 · Oct 15
- Mount Horeb May 7 · Oct 1
- Sauk City May 4 · Oct 6
- Blue Mounds May 7 · Oct 1
- Arena May 7 · Oct 1
- Prairie Du Sac May 4 · Oct 6
- Barneveld May 3 · Oct 7
- Middleton Apr 28 · Oct 15
- Verona Apr 28 · Oct 15
Frequently asked questions
When is the last frost in Black Earth, WI?
The median last spring frost in Black Earth, WI is May 7. There is still about a 10% chance of frost after May 22, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Black Earth, WI?
The median first fall frost is October 1, with about a 10% chance of frost before September 18.
How long is the growing season in Black Earth, WI?
About 147 days between the median last spring frost and first fall frost.
What planting zone is Black Earth, WI?
Black Earth, WI is in USDA hardiness zone 5a.