River Falls, WI planting zone & frost dates
River Falls is in USDA hardiness zone 4b. The last spring frost usually comes around May 11 and the first fall frost around October 1, for a growing season of about 143 days.
Planting calendar for River Falls
Dates are counted from the average last spring frost (May 11) 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 16 – Mar 30 Transplant outdoors: May 18 – May 25 |
| Peppers | Start seeds indoors: Mar 2 – Mar 16 Transplant outdoors: May 25 – Jun 1 |
| Eggplant | Start seeds indoors: Mar 2 – Mar 16 Transplant outdoors: May 25 – Jun 1 |
| Broccoli | Start seeds indoors: Mar 2 – Mar 16 Transplant outdoors: Apr 13 – Apr 27 |
| Cabbage | Start seeds indoors: Mar 2 – Mar 16 Transplant outdoors: Apr 13 – Apr 27 |
| Onions (sets) | Plant outdoors: Apr 13 – Apr 27 |
| Peas | Sow outdoors: Mar 30 – Apr 13 |
| Spinach | Sow outdoors: Mar 30 – Apr 13 |
| Lettuce | Sow outdoors: Apr 13 – Apr 27 |
| Carrots | Sow outdoors: Apr 13 – Apr 27 |
| Potatoes | Plant outdoors: Apr 13 – Apr 27 |
| Beans | Sow outdoors: May 18 – May 25 |
| Sweet corn | Sow outdoors: May 18 – May 25 |
| Cucumbers | Sow outdoors: May 18 – May 25 |
| Squash & zucchini | Sow outdoors: May 18 – May 25 |
| Basil | Start seeds indoors: Mar 30 – Apr 13 Transplant outdoors: May 18 – May 25 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 6 (8 weeks before the average first fall frost on Oct 1).
Useful for zone 4b 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 26 | May 11 | May 26 |
| First 32°F frost in fall is before | Oct 15 | Oct 1 | Sep 19 |
How to read it: in spring there is a 10% chance of a frost after May 26, so that is a safe date for tender plants. In fall there is a 10% chance of frost before September 19. A hard freeze (28°F) usually ends around May 1.
Hardiness zone by ZIP code in River Falls
- 54022 zone 4b
Nearby cities
- Hudson zone 5a, last frost Apr 22
- Menomonie zone 4b, last frost May 9
- Eau Claire zone 4b, last frost Apr 24
- Chippewa Falls zone 4b, last frost May 8
- Onalaska zone 5a, last frost Apr 23
- North La Crosse zone 5a, last frost Apr 23
- La Crosse zone 5a, last frost Apr 27
- Superior zone 5a, last frost May 6
Questions
What growing zone is River Falls, WI?
River Falls is in USDA Plant Hardiness Zone 4b (average extreme winter low -25°F to -20°F), according to the USDA 2023 map.
When is the last frost in River Falls?
The average last spring frost (32°F) in River Falls is May 11. There is still a 10% chance of frost until May 26.
When can I plant tomatoes in River Falls?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around May 18 – May 25. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station River Falls, WI (USC00477226), 1.2 km (0.7 mi) from the city center, elevation 286 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.