Greenfield, WI planting zone & frost dates
Greenfield is in USDA hardiness zone 5b. The last spring frost usually comes around May 3 and the first fall frost around October 14, for a growing season of about 162 days.
Planting calendar for Greenfield
Dates are counted from the average last spring frost (May 3) 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 8 – Mar 22 Transplant outdoors: May 10 – May 17 |
| Peppers | Start seeds indoors: Feb 22 – Mar 8 Transplant outdoors: May 17 – May 24 |
| Eggplant | Start seeds indoors: Feb 22 – Mar 8 Transplant outdoors: May 17 – May 24 |
| Broccoli | Start seeds indoors: Feb 22 – Mar 8 Transplant outdoors: Apr 5 – Apr 19 |
| Cabbage | Start seeds indoors: Feb 22 – Mar 8 Transplant outdoors: Apr 5 – Apr 19 |
| Onions (sets) | Plant outdoors: Apr 5 – Apr 19 |
| Peas | Sow outdoors: Mar 22 – Apr 5 |
| Spinach | Sow outdoors: Mar 22 – Apr 5 |
| Lettuce | Sow outdoors: Apr 5 – Apr 19 |
| Carrots | Sow outdoors: Apr 5 – Apr 19 |
| Potatoes | Plant outdoors: Apr 5 – Apr 19 |
| Beans | Sow outdoors: May 10 – May 17 |
| Sweet corn | Sow outdoors: May 10 – May 17 |
| Cucumbers | Sow outdoors: May 10 – May 17 |
| Squash & zucchini | Sow outdoors: May 10 – May 17 |
| Basil | Start seeds indoors: Mar 22 – Apr 5 Transplant outdoors: May 10 – May 17 |
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).
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 3 | May 19 |
| First 32°F frost in fall is before | Oct 26 | Oct 14 | Sep 30 |
How to read it: in spring there is a 10% chance of a frost after May 19, so that is a safe date for tender plants. In fall there is a 10% chance of frost before September 30. A hard freeze (28°F) usually ends around April 21.
Nearby cities
- Greendale zone 5b, last frost May 3
- West Allis zone 5b, last frost Apr 26
- Franklin zone 5b, last frost May 3
- Wauwatosa zone 5b, last frost Apr 26
- New Berlin zone 5b, last frost May 3
- Milwaukee zone 6a, last frost Apr 26
- Brookfield zone 5b, last frost Apr 30
- Muskego zone 5b, last frost May 3
Questions
What growing zone is Greenfield, WI?
Greenfield 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 Greenfield?
The average last spring frost (32°F) in Greenfield is May 3. There is still a 10% chance of frost until May 19.
When can I plant tomatoes in Greenfield?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around May 10 – May 17. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Hales Corners/Whitnall Park/Bo, WI (USC00473391), 3.0 km (1.9 mi) from the city center, elevation 236 m, based on 10 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.