Waukesha, WI planting zone & frost dates
Waukesha is in USDA hardiness zone 5b. The last spring frost usually comes around May 1 and the first fall frost around October 13, for a growing season of about 162 days.
Planting calendar for Waukesha
Dates are counted from the average last spring frost (May 1) using the typical timing recommended by U.S. extension services. Warm-season crops go out only after the danger of frost has passed and the soil has warmed.
| Crop | When |
|---|---|
| Tomatoes | Start seeds indoors: Mar 6 – Mar 20 Transplant outdoors: May 8 – May 15 |
| Peppers | Start seeds indoors: Feb 20 – Mar 6 Transplant outdoors: May 15 – May 22 |
| Eggplant | Start seeds indoors: Feb 20 – Mar 6 Transplant outdoors: May 15 – May 22 |
| Broccoli | Start seeds indoors: Feb 20 – Mar 6 Transplant outdoors: Apr 3 – Apr 17 |
| Cabbage | Start seeds indoors: Feb 20 – Mar 6 Transplant outdoors: Apr 3 – Apr 17 |
| Onions (sets) | Plant outdoors: Apr 3 – Apr 17 |
| Peas | Sow outdoors: Mar 20 – Apr 3 |
| Spinach | Sow outdoors: Mar 20 – Apr 3 |
| Lettuce | Sow outdoors: Apr 3 – Apr 17 |
| Carrots | Sow outdoors: Apr 3 – Apr 17 |
| Potatoes | Plant outdoors: Apr 3 – Apr 17 |
| Beans | Sow outdoors: May 8 – May 15 |
| Sweet corn | Sow outdoors: May 8 – May 15 |
| Cucumbers | Sow outdoors: May 8 – May 15 |
| Squash & zucchini | Sow outdoors: May 8 – May 15 |
| Basil | Start seeds indoors: Mar 20 – Apr 3 Transplant outdoors: May 8 – May 15 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 18 (8 weeks before the average first fall frost on Oct 13).
Useful for zone 5b gardens
- Seed starting kit with dome — to start seeds indoors before the last frost
- LED grow light for seedlings — stops leggy seedlings
- Frost cloth / plant covers — for late spring and early fall frosts
- Soil thermometer — warm-season crops need soil above 60°F
- Cold frame / mini greenhouse — adds weeks to a short season
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Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Apr 18 | May 1 | May 18 |
| First 32°F frost in fall is before | Oct 25 | Oct 13 | Sep 29 |
How to read it: in spring there is a 10% chance of a frost after May 18, so that is a safe date for tender plants. In fall there is a 10% chance of frost before September 29. A hard freeze (28°F) usually ends around April 19.
Hardiness zone by ZIP code in Waukesha
- 53186 zone 5b
- 53187 zone 5b
- 53188 zone 5b
- 53189 zone 5b
Nearby cities
- Sussex zone 5b, last frost Apr 30
- New Berlin zone 5b, last frost May 3
- Brookfield zone 5b, last frost Apr 30
- Muskego zone 5b, last frost May 3
- Menomonee Falls zone 5b, last frost May 6
- West Allis zone 5b, last frost Apr 26
- Greenfield zone 5b, last frost May 3
- Wauwatosa zone 5b, last frost Apr 26
Questions
What growing zone is Waukesha, WI?
Waukesha is in USDA Plant Hardiness Zone 5b (average extreme winter low -15°F to -10°F), according to the USDA 2023 map.
When is the last frost in Waukesha?
The average last spring frost (32°F) in Waukesha is May 1. There is still a 10% chance of frost until May 18.
When can I plant tomatoes in Waukesha?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around May 8 – May 15. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Waukesha Wwtp, WI (USC00478937), 1.6 km (1.0 mi) from the city center, elevation 240 m, based on 21 years of records. Hardiness zone: USDA Plant Hardiness Zone Map 2023 for the ZIP code nearest to the city center. Microclimates (valleys, hills, cities, coasts) can be warmer or colder: check the local forecast before planting. How we calculate the data.