Rubicon, WI frost dates
Last spring frostMay 8median date
First fall frostOct 3median date
Growing season148 daysfrost-free
Hardiness zone5aZone 5a
How Rubicon compares
- In 8 years out of 10, the last spring frost in Rubicon falls between April 24 and May 24, a 30-day window. The first fall frost falls between September 20 and October 16.
- The median last frost is 3 days later than the Wisconsin median of May 5.
- Its 148-day growing season is longer than 32% of the 749 Wisconsin places with a regular frost season (state median 155 days).
- The last frost is 5 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 159 nights a year at or below 32°F.
- Compared with Waukesha, WI, 39 km away, the last frost here is 7 days later than there and the growing season is 17 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 24 |
| 50% (median) | May 8 |
| 10% (safe for tender plants) | May 24 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 20 |
| 50% (median) | October 3 |
| 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 Rubicon, WI
Rubicon, WI frost dates — last frost May 8, first frost Oct 3, zone 5a. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Feb 13 to Feb 27Transplant outside: Apr 10 to Apr 24
Start indoors: Feb 27 to Mar 13Transplant outside: May 22 to Jun 5
Start indoors: Feb 27 to Mar 13Transplant outside: May 22 to Jun 5
Start indoors: Mar 13 to Mar 27Transplant outside: May 15 to May 29
Start indoors: Mar 13 to Mar 27Transplant outside: Apr 17 to May 1Sow outdoors: Apr 10 to May 15Plant for fall: Aug 8 to Sep 5
Start indoors: Mar 13 to Mar 27Transplant outside: Apr 10 to Apr 24Sow outdoors: Apr 10 to Apr 24Plant for fall: Jul 25 to Aug 15
Start indoors: Mar 13 to Mar 27Transplant outside: Apr 24 to May 8Plant for fall: Jun 27 to Jul 18
Start indoors: Mar 13 to Mar 27Transplant outside: Apr 17 to May 1Plant for fall: Jun 27 to Jul 18
Start indoors: Mar 13 to Mar 27Transplant outside: Apr 24 to May 8Plant for fall: Jun 27 to Jul 18
Start indoors: Mar 27 to Apr 10Transplant outside: May 29 to Jun 12Sow outdoors: May 29 to Jun 12
Start indoors: Mar 27 to Apr 10Transplant outside: May 15 to May 29
Sow outdoors: Mar 27 to Apr 17Plant for fall: Jul 11 to Aug 1
Sow outdoors: Mar 27 to Apr 17Plant for fall: Aug 8 to Aug 29
Sow outdoors: Apr 3 to May 15Plant for fall: Aug 22 to Sep 12
Start indoors: Apr 10 to Apr 17Transplant outside: May 22 to May 29Sow outdoors: May 15 to May 29Plant for fall: Jul 18 to Aug 1
Start indoors: Apr 10 to Apr 17Sow outdoors: May 15 to May 29Plant for fall: Jul 25 to Aug 8
Start indoors: Apr 10 to Apr 17Sow outdoors: May 15 to May 29
Start indoors: Apr 10 to Apr 17Transplant outside: May 22 to Jun 5
Sow outdoors: Apr 17 to May 15Plant for fall: Jul 11 to Jul 25
Sow outdoors: Apr 17 to May 15Plant for fall: Jul 25 to Aug 8
Sow outdoors: Apr 17 to May 8
Sow outdoors: Apr 24 to May 22Plant for fall: Jul 25 to Aug 8
Sow outdoors: Apr 24 to May 15Plant for fall: Aug 8 to Aug 29
Sow outdoors: May 15 to Jun 5Plant for fall: Jul 18 to Aug 1
Sow outdoors: May 15 to May 29
Transplant outside: May 22 to Jun 12
Plant for fall: Sep 19 to Oct 24
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Rubicon, WI
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 13 – Feb 27 | Apr 10 – Apr 24 | — | — |
| Peppers | Feb 27 – Mar 13 | May 22 – Jun 5 | — | — |
| Eggplant | Feb 27 – Mar 13 | May 22 – Jun 5 | — | — |
| Tomatoes | Mar 13 – Mar 27 | May 15 – May 29 | — | — |
| Lettuce | Mar 13 – Mar 27 | Apr 17 – May 1 | Apr 10 – May 15 | Aug 8 – Sep 5 |
| Kale | Mar 13 – Mar 27 | Apr 10 – Apr 24 | Apr 10 – Apr 24 | Jul 25 – Aug 15 |
| Broccoli | Mar 13 – Mar 27 | Apr 24 – May 8 | — | Jun 27 – Jul 18 |
| Cabbage | Mar 13 – Mar 27 | Apr 17 – May 1 | — | Jun 27 – Jul 18 |
| Cauliflower | Mar 13 – Mar 27 | Apr 24 – May 8 | — | Jun 27 – Jul 18 |
| Okra | Mar 27 – Apr 10 | May 29 – Jun 12 | May 29 – Jun 12 | — |
| Basil | Mar 27 – Apr 10 | May 15 – May 29 | — | — |
| Peas | — | — | Mar 27 – Apr 17 | Jul 11 – Aug 1 |
| Spinach | — | — | Mar 27 – Apr 17 | Aug 8 – Aug 29 |
| Radishes | — | — | Apr 3 – May 15 | Aug 22 – Sep 12 |
| Cucumbers | Apr 10 – Apr 17 | May 22 – May 29 | May 15 – May 29 | Jul 18 – Aug 1 |
| Zucchini & Summer Squash | Apr 10 – Apr 17 | — | May 15 – May 29 | Jul 25 – Aug 8 |
| Winter Squash & Pumpkins | Apr 10 – Apr 17 | — | May 15 – May 29 | — |
| Melons & Watermelon | Apr 10 – Apr 17 | May 22 – Jun 5 | — | — |
| Carrots | — | — | Apr 17 – May 15 | Jul 11 – Jul 25 |
| Beets | — | — | Apr 17 – May 15 | Jul 25 – Aug 8 |
| Potatoes | — | — | Apr 17 – May 8 | — |
| Swiss Chard | — | — | Apr 24 – May 22 | Jul 25 – Aug 8 |
| Cilantro | — | — | Apr 24 – May 15 | Aug 8 – Aug 29 |
| Green Beans | — | — | May 15 – Jun 5 | Jul 18 – Aug 1 |
| Sweet Corn | — | — | May 15 – May 29 | — |
| Sweet Potatoes | — | May 22 – Jun 12 | — | — |
| Garlic | — | — | — | Sep 19 – Oct 24 |
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 Hartford Wwtp, WI weather station, 4 km away (elevation 961 ft (293 m)).
Frost dates near Rubicon
- Neosho Apr 28 · Oct 10
- Hartford May 8 · Oct 3
- Woodland Apr 28 · Oct 10
- Iron Ridge Apr 28 · Oct 10
- Ashippun Apr 30 · Oct 12
- Hustisford Apr 28 · Oct 10
- Slinger May 5 · Oct 5
- Lebanon Apr 28 · Oct 10
- North Lake Apr 30 · Oct 12
- Allenton May 1 · Oct 12
Frequently asked questions
When is the last frost in Rubicon, WI?
The median last spring frost in Rubicon, WI is May 8. There is still about a 10% chance of frost after May 24, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Rubicon, WI?
The median first fall frost is October 3, with about a 10% chance of frost before September 20.
How long is the growing season in Rubicon, WI?
About 148 days between the median last spring frost and first fall frost.
What planting zone is Rubicon, WI?
Rubicon, WI is in USDA hardiness zone 5a.