Williston, ND planting zone & frost dates
Williston is in USDA hardiness zone 4a. The last spring frost usually comes around May 21 and the first fall frost around September 21, for a growing season of about 123 days.
Planting calendar for Williston
Dates are counted from the average last spring frost (May 21) 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 26 – Apr 9 Transplant outdoors: May 28 – Jun 4 |
| Peppers | Start seeds indoors: Mar 12 – Mar 26 Transplant outdoors: Jun 4 – Jun 11 |
| Eggplant | Start seeds indoors: Mar 12 – Mar 26 Transplant outdoors: Jun 4 – Jun 11 |
| Broccoli | Start seeds indoors: Mar 12 – Mar 26 Transplant outdoors: Apr 23 – May 7 |
| Cabbage | Start seeds indoors: Mar 12 – Mar 26 Transplant outdoors: Apr 23 – May 7 |
| Onions (sets) | Plant outdoors: Apr 23 – May 7 |
| Peas | Sow outdoors: Apr 9 – Apr 23 |
| Spinach | Sow outdoors: Apr 9 – Apr 23 |
| Lettuce | Sow outdoors: Apr 23 – May 7 |
| Carrots | Sow outdoors: Apr 23 – May 7 |
| Potatoes | Plant outdoors: Apr 23 – May 7 |
| Beans | Sow outdoors: May 28 – Jun 4 |
| Sweet corn | Sow outdoors: May 28 – Jun 4 |
| Cucumbers | Sow outdoors: May 28 – Jun 4 |
| Squash & zucchini | Sow outdoors: May 28 – Jun 4 |
| Basil | Start seeds indoors: Apr 9 – Apr 23 Transplant outdoors: May 28 – Jun 4 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Jul 27 (8 weeks before the average first fall frost on Sep 21).
Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | May 8 | May 21 | Jun 3 |
| First 32°F frost in fall is before | Oct 2 | Sep 21 | Sep 9 |
How to read it: in spring there is a 10% chance of a frost after June 3, so that is a safe date for tender plants. In fall there is a 10% chance of frost before September 9. A hard freeze (28°F) usually ends around May 11.
Hardiness zone by ZIP code in Williston
- 58801 zone 4a
- 58802 zone 4a
- 58803 zone 4a
Nearby cities
- Dickinson zone 4a, last frost May 20
- Minot zone 4a, last frost May 10
- Mandan zone 4a, last frost May 13
- Bismarck zone 4a, last frost May 10
- Jamestown zone 4b, last frost May 8
- Grand Forks zone 4a, last frost May 10
- West Fargo zone 4a, last frost May 10
- Fargo zone 4a, last frost May 5
Questions
What growing zone is Williston, ND?
Williston is in USDA Plant Hardiness Zone 4a (average extreme winter low -30°F to -25°F), according to the USDA 2023 map.
When is the last frost in Williston?
The average last spring frost (32°F) in Williston is May 21. There is still a 10% chance of frost until June 3.
When can I plant tomatoes in Williston?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around May 28 – Jun 4. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Williston Sloulin Intl Ap, ND (USW00094014), 3.3 km (2.0 mi) from the city center, elevation 580 m, based on 29 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.