Mequon, WI planting zone & frost dates
Mequon is in USDA hardiness zone 5b. The last spring frost usually comes around May 6 and the first fall frost around October 8, for a growing season of about 154 days.
Planting calendar for Mequon
Dates are counted from the average last spring frost (May 6) 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 11 – Mar 25 Transplant outdoors: May 13 – May 20 |
| Peppers | Start seeds indoors: Feb 25 – Mar 11 Transplant outdoors: May 20 – May 27 |
| Eggplant | Start seeds indoors: Feb 25 – Mar 11 Transplant outdoors: May 20 – May 27 |
| Broccoli | Start seeds indoors: Feb 25 – Mar 11 Transplant outdoors: Apr 8 – Apr 22 |
| Cabbage | Start seeds indoors: Feb 25 – Mar 11 Transplant outdoors: Apr 8 – Apr 22 |
| Onions (sets) | Plant outdoors: Apr 8 – Apr 22 |
| Peas | Sow outdoors: Mar 25 – Apr 8 |
| Spinach | Sow outdoors: Mar 25 – Apr 8 |
| Lettuce | Sow outdoors: Apr 8 – Apr 22 |
| Carrots | Sow outdoors: Apr 8 – Apr 22 |
| Potatoes | Plant outdoors: Apr 8 – Apr 22 |
| Beans | Sow outdoors: May 13 – May 20 |
| Sweet corn | Sow outdoors: May 13 – May 20 |
| Cucumbers | Sow outdoors: May 13 – May 20 |
| Squash & zucchini | Sow outdoors: May 13 – May 20 |
| Basil | Start seeds indoors: Mar 25 – Apr 8 Transplant outdoors: May 13 – May 20 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 13 (8 weeks before the average first fall frost on Oct 8).
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 22 | May 6 | May 25 |
| First 32°F frost in fall is before | Oct 24 | Oct 8 | Sep 26 |
How to read it: in spring there is a 10% chance of a frost after May 25, so that is a safe date for tender plants. In fall there is a 10% chance of frost before September 26. A hard freeze (28°F) usually ends around April 24.
Hardiness zone by ZIP code in Mequon
- 53092 zone 6a
- 53097 zone 5b
Nearby cities
- Germantown zone 5b, last frost May 6
- Brown Deer zone 6a, last frost Apr 26
- Cedarburg zone 5b, last frost Apr 23
- Menomonee Falls zone 5b, last frost May 6
- Glendale zone 6a, last frost Apr 26
- Grafton zone 6a, last frost Apr 23
- Whitefish Bay zone 6a, last frost Apr 26
- Wauwatosa zone 5b, last frost Apr 26
Questions
What growing zone is Mequon, WI?
Mequon is in USDA Plant Hardiness Zone 5b (average extreme winter low -15°F to -10°F), according to the USDA 2023 map. Some ZIP codes of the city fall in zone 6a.
When is the last frost in Mequon?
The average last spring frost (32°F) in Mequon is May 6. There is still a 10% chance of frost until May 25.
When can I plant tomatoes in Mequon?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around May 13 – May 20. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Germantown, WI (USC00473058), 7.9 km (4.9 mi) from the city center, elevation 259 m, based on 30 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.