Mason, WI frost dates
Last spring frostMay 20median date
First fall frostOct 1median date
Growing season134 daysfrost-free
Hardiness zone4bZone 4b
How Mason compares
- In 8 years out of 10, the last spring frost in Mason falls between May 5 and June 2, a 28-day window. The first fall frost falls between September 19 and October 13.
- The median last frost is 15 days later than the Wisconsin median of May 5.
- Its 134-day growing season is longer than 11% of the 749 Wisconsin places with a regular frost season (state median 155 days).
- The last frost is 12 days later than the zone 4b median of May 8. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 4b chart.
- The weather station records an average of 183 nights a year at or below 32°F.
- Compared with Duluth, MN, 85 km away, the last frost here is 6 days later than there and the growing season is 17 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 5 |
| 50% (median) | May 20 |
| 10% (safe for tender plants) | June 2 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 19 |
| 50% (median) | October 1 |
| 90% (late) | October 13 |
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 Mason, WI
Mason, WI frost dates — last frost May 20, first frost Oct 1, zone 4b. whenisthelastfrost.com
Crop
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Start indoors: Feb 25 to Mar 11Transplant outside: Apr 22 to May 6
Start indoors: Mar 11 to Mar 25Transplant outside: Jun 3 to Jun 17
Start indoors: Mar 11 to Mar 25Transplant outside: Jun 3 to Jun 17
Start indoors: Mar 25 to Apr 8Transplant outside: May 27 to Jun 10
Start indoors: Mar 25 to Apr 8Transplant outside: Apr 29 to May 13Sow outdoors: Apr 22 to May 27Plant for fall: Aug 6 to Sep 3
Start indoors: Mar 25 to Apr 8Transplant outside: Apr 22 to May 6Sow outdoors: Apr 22 to May 6Plant for fall: Jul 23 to Aug 13
Start indoors: Mar 25 to Apr 8Transplant outside: May 6 to May 20Plant for fall: Jun 25 to Jul 16
Start indoors: Mar 25 to Apr 8Transplant outside: Apr 29 to May 13Plant for fall: Jun 25 to Jul 16
Start indoors: Mar 25 to Apr 8Transplant outside: May 6 to May 20Plant for fall: Jun 25 to Jul 16
Start indoors: Apr 8 to Apr 22Transplant outside: Jun 10 to Jun 24Sow outdoors: Jun 10 to Jun 24
Start indoors: Apr 8 to Apr 22Transplant outside: May 27 to Jun 10
Sow outdoors: Apr 8 to Apr 29Plant for fall: Jul 9 to Jul 30
Sow outdoors: Apr 8 to Apr 29Plant for fall: Aug 6 to Aug 27
Sow outdoors: Apr 15 to May 27Plant for fall: Aug 20 to Sep 10
Start indoors: Apr 22 to Apr 29Transplant outside: Jun 3 to Jun 10Sow outdoors: May 27 to Jun 10Plant for fall: Jul 16 to Jul 30
Start indoors: Apr 22 to Apr 29Sow outdoors: May 27 to Jun 10Plant for fall: Jul 23 to Aug 6
Start indoors: Apr 22 to Apr 29Sow outdoors: May 27 to Jun 10
Start indoors: Apr 22 to Apr 29Transplant outside: Jun 3 to Jun 17
Sow outdoors: Apr 29 to May 27Plant for fall: Jul 9 to Jul 23
Sow outdoors: Apr 29 to May 27Plant for fall: Jul 23 to Aug 6
Sow outdoors: Apr 29 to May 20
Sow outdoors: May 6 to Jun 3Plant for fall: Jul 23 to Aug 6
Sow outdoors: May 6 to May 27Plant for fall: Aug 6 to Aug 27
Sow outdoors: May 27 to Jun 17Plant for fall: Jul 16 to Jul 30
Sow outdoors: May 27 to Jun 10
Transplant outside: Jun 3 to Jun 24
Plant for fall: Sep 17 to Oct 22
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Mason, WI
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 25 – Mar 11 | Apr 22 – May 6 | — | — |
| Peppers | Mar 11 – Mar 25 | Jun 3 – Jun 17 | — | — |
| Eggplant | Mar 11 – Mar 25 | Jun 3 – Jun 17 | — | — |
| Tomatoes | Mar 25 – Apr 8 | May 27 – Jun 10 | — | — |
| Lettuce | Mar 25 – Apr 8 | Apr 29 – May 13 | Apr 22 – May 27 | Aug 6 – Sep 3 |
| Kale | Mar 25 – Apr 8 | Apr 22 – May 6 | Apr 22 – May 6 | Jul 23 – Aug 13 |
| Broccoli | Mar 25 – Apr 8 | May 6 – May 20 | — | Jun 25 – Jul 16 |
| Cabbage | Mar 25 – Apr 8 | Apr 29 – May 13 | — | Jun 25 – Jul 16 |
| Cauliflower | Mar 25 – Apr 8 | May 6 – May 20 | — | Jun 25 – Jul 16 |
| Okra | Apr 8 – Apr 22 | Jun 10 – Jun 24 | Jun 10 – Jun 24 | — |
| Basil | Apr 8 – Apr 22 | May 27 – Jun 10 | — | — |
| Peas | — | — | Apr 8 – Apr 29 | Jul 9 – Jul 30 |
| Spinach | — | — | Apr 8 – Apr 29 | Aug 6 – Aug 27 |
| Radishes | — | — | Apr 15 – May 27 | Aug 20 – Sep 10 |
| Cucumbers | Apr 22 – Apr 29 | Jun 3 – Jun 10 | May 27 – Jun 10 | Jul 16 – Jul 30 |
| Zucchini & Summer Squash | Apr 22 – Apr 29 | — | May 27 – Jun 10 | Jul 23 – Aug 6 |
| Winter Squash & Pumpkins | Apr 22 – Apr 29 | — | May 27 – Jun 10 | — |
| Melons & Watermelon | Apr 22 – Apr 29 | Jun 3 – Jun 17 | — | — |
| Carrots | — | — | Apr 29 – May 27 | Jul 9 – Jul 23 |
| Beets | — | — | Apr 29 – May 27 | Jul 23 – Aug 6 |
| Potatoes | — | — | Apr 29 – May 20 | — |
| Swiss Chard | — | — | May 6 – Jun 3 | Jul 23 – Aug 6 |
| Cilantro | — | — | May 6 – May 27 | Aug 6 – Aug 27 |
| Green Beans | — | — | May 27 – Jun 17 | Jul 16 – Jul 30 |
| Sweet Corn | — | — | May 27 – Jun 10 | — |
| Sweet Potatoes | — | Jun 3 – Jun 24 | — | — |
| 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 Drummond, WI weather station, 16 km away (elevation 1,339 ft (408 m)).
Frost dates near Mason
- Benoit May 23 · Sep 29
- Grand View May 20 · Oct 1
- Drummond May 20 · Oct 1
- Marengo May 26 · Sep 27
- Cable May 20 · Oct 1
- Iron River May 24 · Sep 26
- High Bridge May 26 · Sep 27
- Washburn May 23 · Oct 2
- Ashland May 20 · Oct 2
- Clam Lake May 16 · Sep 30
Frequently asked questions
When is the last frost in Mason, WI?
The median last spring frost in Mason, WI is May 20. There is still about a 10% chance of frost after June 2, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Mason, WI?
The median first fall frost is October 1, with about a 10% chance of frost before September 19.
How long is the growing season in Mason, WI?
About 134 days between the median last spring frost and first fall frost.
What planting zone is Mason, WI?
Mason, WI is in USDA hardiness zone 4b.