Brookfield, WI planting zone & frost dates
Brookfield is in USDA hardiness zone 5b. The last spring frost usually comes around April 30 and the first fall frost around October 14, for a growing season of about 164 days.
Planting calendar for Brookfield
Dates are counted from the average last spring frost (April 30) 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 5 – Mar 19 Transplant outdoors: May 7 – May 14 |
| Peppers | Start seeds indoors: Feb 19 – Mar 5 Transplant outdoors: May 14 – May 21 |
| Eggplant | Start seeds indoors: Feb 19 – Mar 5 Transplant outdoors: May 14 – May 21 |
| Broccoli | Start seeds indoors: Feb 19 – Mar 5 Transplant outdoors: Apr 2 – Apr 16 |
| Cabbage | Start seeds indoors: Feb 19 – Mar 5 Transplant outdoors: Apr 2 – Apr 16 |
| Onions (sets) | Plant outdoors: Apr 2 – Apr 16 |
| Peas | Sow outdoors: Mar 19 – Apr 2 |
| Spinach | Sow outdoors: Mar 19 – Apr 2 |
| Lettuce | Sow outdoors: Apr 2 – Apr 16 |
| Carrots | Sow outdoors: Apr 2 – Apr 16 |
| Potatoes | Plant outdoors: Apr 2 – Apr 16 |
| Beans | Sow outdoors: May 7 – May 14 |
| Sweet corn | Sow outdoors: May 7 – May 14 |
| Cucumbers | Sow outdoors: May 7 – May 14 |
| Squash & zucchini | Sow outdoors: May 7 – May 14 |
| Basil | Start seeds indoors: Mar 19 – Apr 2 Transplant outdoors: May 7 – May 14 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 19 (8 weeks before the average first fall frost on Oct 14).
Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Apr 16 | Apr 30 | May 15 |
| First 32°F frost in fall is before | Oct 27 | Oct 14 | Sep 28 |
How to read it: in spring there is a 10% chance of a frost after May 15, so that is a safe date for tender plants. In fall there is a 10% chance of frost before September 28. A hard freeze (28°F) usually ends around April 19.
Hardiness zone by ZIP code in Brookfield
- 53005 zone 5b
- 53008 zone 5b
- 53045 zone 5b
Nearby cities
- New Berlin zone 5b, last frost May 3
- Wauwatosa zone 5b, last frost Apr 26
- West Allis zone 5b, last frost Apr 26
- Menomonee Falls zone 5b, last frost May 6
- Waukesha zone 5b, last frost May 1
- Greenfield zone 5b, last frost May 3
- Sussex zone 5b, last frost Apr 30
- Muskego zone 5b, last frost May 3
Questions
What growing zone is Brookfield, WI?
Brookfield 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 Brookfield?
The average last spring frost (32°F) in Brookfield is April 30. There is still a 10% chance of frost until May 15.
When can I plant tomatoes in Brookfield?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around May 7 – May 14. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Brookfield Wwtp, WI (USC00471062), 5.8 km (3.6 mi) from the city center, elevation 253 m, based on 13 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.