Madison, Wisconsin: planting zone & frost dates
Madison is in USDA plant hardiness zone 5b, where the average coldest winter night reaches -15 to -10°F (-26.1 to -23.3°C). The typical last spring frost is around May 7 and the first fall frost around Oct 3.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | May 17 | Sep 26 |
| Typical planning date (30% risk) | May 7 | Oct 3 |
| Median (50%) | May 1 | Oct 9 |
How to read this: after the spring "10% risk" date, a 32°F frost happens in only about 1 year in 10. In fall, the "10% risk" date is the early end — a frost before it happens about 1 year in 10.
Frost data comes from NOAA station UW ARBORETUM - MADISON, WI (USC00470273), 3.2 mi (5.2 km) from the city center and 52 ft lower than the city center (-16 m). Record used for the 1991–2020 normals: 27 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Madison
Madison spans more than one half-zone. Share of the city's land area by zone (via its 16 ZIP codes): 5b (83%), 5a (17%). The headline zone is the one covering the most land. Look up your ZIP for your exact zone.
Vegetable planting calendar for Madison
Dates are counted from the 30%-risk frost dates above (last frost May 7, first frost Oct 3). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Mar 12 – Mar 26 | May 14 – May 28 | — | — |
| Pepper | Feb 26 – Mar 12 | May 21 – Jun 4 | — | — |
| Lettuce | Mar 26 – Apr 9 | Apr 23 – May 14 | Apr 9 – May 21 | Jul 25 – Aug 22 |
| Green Beans | — | — | May 14 – Jun 18 | Jul 11 – Jul 25 |
| Sweet Corn | — | — | May 14 – Jun 11 | — |
| Zucchini & Summer Squash | Apr 9 – Apr 16 | May 14 – May 28 | May 14 – Jun 4 | Jul 11 – Jul 25 |
| Cucumber | Apr 9 – Apr 16 | May 21 – May 28 | May 14 – Jun 4 | Jul 11 – Jul 25 |
| Carrot | — | — | Apr 16 – May 21 | Jul 11 – Jul 25 |
| Onion | Feb 12 – Feb 26 | Apr 9 – Apr 23 | — | — |
| Potato | — | Apr 9 – Apr 30 | — | — |
| Basil | Mar 26 – Apr 9 | May 21 – Jun 4 | May 21 – Jun 11 | — |
| Spinach | — | — | Mar 26 – Apr 23 | Aug 8 – Sep 5 |
| Kale | Mar 12 – Mar 26 | Apr 9 – Apr 30 | Apr 9 – Apr 30 | Jul 25 – Aug 22 |
| Broccoli | Mar 12 – Mar 26 | Apr 23 – May 14 | — | Jul 11 – Jul 25 |
| Peas | — | — | Mar 26 – Apr 16 | Jul 25 – Aug 8 |
| Eggplant | Feb 26 – Mar 12 | May 21 – Jun 4 | — | — |
| Cabbage | Mar 12 – Mar 26 | Apr 9 – Apr 23 | — | Jul 11 – Jul 25 |
| Radish | — | — | Apr 2 – May 21 | Aug 22 – Sep 19 |
| Strawberry | — | Apr 9 – Apr 30 | — | — |
| Beets | — | — | Apr 16 – May 28 | Jul 25 – Aug 8 |
Nearby cities in Wisconsin
- Milwaukee — zone 6a, last frost May 2, first frost Oct 12
- Kenosha — zone 5b, last frost May 3, first frost Oct 14
- Racine — zone 6a, last frost Apr 27, first frost Oct 18
- Green Bay — zone 5b, last frost May 13, first frost Oct 2
More: all Wisconsin cities · other zone 5b cities: Des Moines, IA, Aurora, IL, Fort Collins, CO, Naperville, IL, Rockford, IL, Elgin, IL, Greeley, CO, Green Bay, WI
Madison gardening questions
When is the last frost in Madison, WI?
Plan around May 7. At NOAA's Uw Arboretum - Madison, WI station, 3.2 mi from the city center, there is a 30% chance of a 32°F frost after that date. Half of springs have their last frost by May 1, and after May 17 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Apr 20. The 90% and 10% dates are 29 days apart, close to the 36-day median for cities on this site.
When should I plant tomatoes in Madison, WI?
Start seeds indoors Mar 12 – Mar 26 and set transplants outside May 14 – May 28, once nights stay above 50°F and the soil is near 60°F. That leaves 149 days between the 30% frost dates, enough for most varieties including 80–85-day slicers. More: tomato planting dates by zone.
How long is the growing season in Madison?
About 161 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 140 days, and in 1 year in 10 it runs 179 days or more. In fall there is a 10% chance of frost by Sep 26 and a 30% chance by Oct 3. That ranks 4th longest of 5 Wisconsin cities on this site.
When should I plant a fall garden in Madison?
Count back from the first fall frost (Oct 3): transplant broccoli Jul 11 – Jul 25; sow kale Jul 25 – Aug 22; sow lettuce Jul 25 – Aug 22; sow radishes Aug 22 – Sep 19. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Oct 20. How the math works: succession and fall planting.
Did Madison's hardiness zone change on the 2023 map?
Yes. Most of Madison was zone 5a on the 2012 map and is zone 5b on the 2023 map — half a zone warmer, like about 56% of U.S. ZIP codes. The shift comes from a newer 1991–2020 averaging period plus more weather stations and better mapping; it does not mean last frost comes earlier. Why the 2023 map is warmer.
Is all of Madison in zone 5b?
No. Zone 5b covers about 83% of the city's land; the rest is in 5a (17%), measured across the city's 16 ZIP codes. Check your own ZIP code in the table above or with the ZIP lookup.