Hillsboro, WI frost dates
Last spring frostMay 12median date
First fall frostSep 29median date
Growing season140 daysfrost-free
Hardiness zone4bZone 4b
How Hillsboro compares
- In 8 years out of 10, the last spring frost in Hillsboro falls between April 28 and May 26, a 28-day window. The first fall frost falls between September 17 and October 10.
- The median last frost is 7 days later than the Wisconsin median of May 5.
- Its 140-day growing season is longer than 16% of the 749 Wisconsin places with a regular frost season (state median 155 days).
- The last frost is 4 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 181 nights a year at or below 32°F.
- Compared with La Crosse, WI, 69 km away, the last frost here is 15 days later than there and the growing season is 29 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 28 |
| 50% (median) | May 12 |
| 10% (safe for tender plants) | May 26 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 17 |
| 50% (median) | September 29 |
| 90% (late) | October 10 |
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 Hillsboro, WI
Hillsboro, WI frost dates — last frost May 12, first frost Sep 29, zone 4b. whenisthelastfrost.com
Crop
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Start indoors: Feb 17 to Mar 3Transplant outside: Apr 14 to Apr 28
Start indoors: Mar 3 to Mar 17Transplant outside: May 26 to Jun 9
Start indoors: Mar 3 to Mar 17Transplant outside: May 26 to Jun 9
Start indoors: Mar 17 to Mar 31Transplant outside: May 19 to Jun 2
Start indoors: Mar 17 to Mar 31Transplant outside: Apr 21 to May 5Sow outdoors: Apr 14 to May 19Plant for fall: Aug 4 to Sep 1
Start indoors: Mar 17 to Mar 31Transplant outside: Apr 14 to Apr 28Sow outdoors: Apr 14 to Apr 28Plant for fall: Jul 21 to Aug 11
Start indoors: Mar 17 to Mar 31Transplant outside: Apr 28 to May 12Plant for fall: Jun 23 to Jul 14
Start indoors: Mar 17 to Mar 31Transplant outside: Apr 21 to May 5Plant for fall: Jun 23 to Jul 14
Start indoors: Mar 17 to Mar 31Transplant outside: Apr 28 to May 12Plant for fall: Jun 23 to Jul 14
Start indoors: Mar 31 to Apr 14Transplant outside: Jun 2 to Jun 16Sow outdoors: Jun 2 to Jun 16
Start indoors: Mar 31 to Apr 14Transplant outside: May 19 to Jun 2
Sow outdoors: Mar 31 to Apr 21Plant for fall: Jul 7 to Jul 28
Sow outdoors: Mar 31 to Apr 21Plant for fall: Aug 4 to Aug 25
Sow outdoors: Apr 7 to May 19Plant for fall: Aug 18 to Sep 8
Start indoors: Apr 14 to Apr 21Transplant outside: May 26 to Jun 2Sow outdoors: May 19 to Jun 2Plant for fall: Jul 14 to Jul 28
Start indoors: Apr 14 to Apr 21Sow outdoors: May 19 to Jun 2Plant for fall: Jul 21 to Aug 4
Start indoors: Apr 14 to Apr 21Sow outdoors: May 19 to Jun 2
Start indoors: Apr 14 to Apr 21Transplant outside: May 26 to Jun 9
Sow outdoors: Apr 21 to May 19Plant for fall: Jul 7 to Jul 21
Sow outdoors: Apr 21 to May 19Plant for fall: Jul 21 to Aug 4
Sow outdoors: Apr 21 to May 12
Sow outdoors: Apr 28 to May 26Plant for fall: Jul 21 to Aug 4
Sow outdoors: Apr 28 to May 19Plant for fall: Aug 4 to Aug 25
Sow outdoors: May 19 to Jun 9Plant for fall: Jul 14 to Jul 28
Sow outdoors: May 19 to Jun 2
Transplant outside: May 26 to Jun 16
Plant for fall: Sep 15 to Oct 20
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Hillsboro, WI
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 17 – Mar 3 | Apr 14 – Apr 28 | — | — |
| Peppers | Mar 3 – Mar 17 | May 26 – Jun 9 | — | — |
| Eggplant | Mar 3 – Mar 17 | May 26 – Jun 9 | — | — |
| Tomatoes | Mar 17 – Mar 31 | May 19 – Jun 2 | — | — |
| Lettuce | Mar 17 – Mar 31 | Apr 21 – May 5 | Apr 14 – May 19 | Aug 4 – Sep 1 |
| Kale | Mar 17 – Mar 31 | Apr 14 – Apr 28 | Apr 14 – Apr 28 | Jul 21 – Aug 11 |
| Broccoli | Mar 17 – Mar 31 | Apr 28 – May 12 | — | Jun 23 – Jul 14 |
| Cabbage | Mar 17 – Mar 31 | Apr 21 – May 5 | — | Jun 23 – Jul 14 |
| Cauliflower | Mar 17 – Mar 31 | Apr 28 – May 12 | — | Jun 23 – Jul 14 |
| Okra | Mar 31 – Apr 14 | Jun 2 – Jun 16 | Jun 2 – Jun 16 | — |
| Basil | Mar 31 – Apr 14 | May 19 – Jun 2 | — | — |
| Peas | — | — | Mar 31 – Apr 21 | Jul 7 – Jul 28 |
| Spinach | — | — | Mar 31 – Apr 21 | Aug 4 – Aug 25 |
| Radishes | — | — | Apr 7 – May 19 | Aug 18 – Sep 8 |
| Cucumbers | Apr 14 – Apr 21 | May 26 – Jun 2 | May 19 – Jun 2 | Jul 14 – Jul 28 |
| Zucchini & Summer Squash | Apr 14 – Apr 21 | — | May 19 – Jun 2 | Jul 21 – Aug 4 |
| Winter Squash & Pumpkins | Apr 14 – Apr 21 | — | May 19 – Jun 2 | — |
| Melons & Watermelon | Apr 14 – Apr 21 | May 26 – Jun 9 | — | — |
| Carrots | — | — | Apr 21 – May 19 | Jul 7 – Jul 21 |
| Beets | — | — | Apr 21 – May 19 | Jul 21 – Aug 4 |
| Potatoes | — | — | Apr 21 – May 12 | — |
| Swiss Chard | — | — | Apr 28 – May 26 | Jul 21 – Aug 4 |
| Cilantro | — | — | Apr 28 – May 19 | Aug 4 – Aug 25 |
| Green Beans | — | — | May 19 – Jun 9 | Jul 14 – Jul 28 |
| Sweet Corn | — | — | May 19 – Jun 2 | — |
| Sweet Potatoes | — | May 26 – Jun 16 | — | — |
| Garlic | — | — | — | Sep 15 – Oct 20 |
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 Hillsboro 2sw, WI weather station, 6 km away (elevation 1,043 ft (318 m)).
Frost dates near Hillsboro
- Wonewoc May 5 · Oct 4
- Cazenovia May 12 · Sep 29
- Union Center May 5 · Oct 4
- La Farge Apr 27 · Oct 14
- Elroy May 5 · Oct 4
- Ontario Apr 27 · Oct 14
- Viola May 7 · Oct 2
- Kendall May 5 · Oct 4
- La Valle May 2 · Oct 7
- Richland Center May 5 · Oct 6
Frequently asked questions
When is the last frost in Hillsboro, WI?
The median last spring frost in Hillsboro, WI is May 12. There is still about a 10% chance of frost after May 26, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Hillsboro, WI?
The median first fall frost is September 29, with about a 10% chance of frost before September 17.
How long is the growing season in Hillsboro, WI?
About 140 days between the median last spring frost and first fall frost.
What planting zone is Hillsboro, WI?
Hillsboro, WI is in USDA hardiness zone 4b.