Jamestown, ND planting zone & frost dates
Jamestown is in USDA hardiness zone 4b. The last spring frost usually comes around May 8 and the first fall frost around September 29, for a growing season of about 143 days.
Planting calendar for Jamestown
Dates are counted from the average last spring frost (May 8) 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 13 – Mar 27 Transplant outdoors: May 15 – May 22 |
| Peppers | Start seeds indoors: Feb 27 – Mar 13 Transplant outdoors: May 22 – May 29 |
| Eggplant | Start seeds indoors: Feb 27 – Mar 13 Transplant outdoors: May 22 – May 29 |
| Broccoli | Start seeds indoors: Feb 27 – Mar 13 Transplant outdoors: Apr 10 – Apr 24 |
| Cabbage | Start seeds indoors: Feb 27 – Mar 13 Transplant outdoors: Apr 10 – Apr 24 |
| Onions (sets) | Plant outdoors: Apr 10 – Apr 24 |
| Peas | Sow outdoors: Mar 27 – Apr 10 |
| Spinach | Sow outdoors: Mar 27 – Apr 10 |
| Lettuce | Sow outdoors: Apr 10 – Apr 24 |
| Carrots | Sow outdoors: Apr 10 – Apr 24 |
| Potatoes | Plant outdoors: Apr 10 – Apr 24 |
| Beans | Sow outdoors: May 15 – May 22 |
| Sweet corn | Sow outdoors: May 15 – May 22 |
| Cucumbers | Sow outdoors: May 15 – May 22 |
| Squash & zucchini | Sow outdoors: May 15 – May 22 |
| Basil | Start seeds indoors: Mar 27 – Apr 10 Transplant outdoors: May 15 – May 22 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 4 (8 weeks before the average first fall frost on Sep 29).
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
As an Amazon Associate, FrostZoneMap earns from qualifying purchases, at no extra cost to you.
Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Apr 26 | May 8 | May 21 |
| First 32°F frost in fall is before | Oct 11 | Sep 29 | Sep 17 |
How to read it: in spring there is a 10% chance of a frost after May 21, so that is a safe date for tender plants. In fall there is a 10% chance of frost before September 17. A hard freeze (28°F) usually ends around April 30.
Hardiness zone by ZIP code in Jamestown
- 58401 zone 4b
- 58402 zone 4a
- 58405 zone 4b
Nearby cities
- West Fargo zone 4a, last frost May 10
- Fargo zone 4a, last frost May 5
- Grand Forks zone 4a, last frost May 10
- Bismarck zone 4a, last frost May 10
- Mandan zone 4a, last frost May 13
- Minot zone 4a, last frost May 10
- Dickinson zone 4a, last frost May 20
- Williston zone 4a, last frost May 21
Questions
What growing zone is Jamestown, ND?
Jamestown is in USDA Plant Hardiness Zone 4b (average extreme winter low -25°F to -20°F), according to the USDA 2023 map. Some ZIP codes of the city fall in zone 4a.
When is the last frost in Jamestown?
The average last spring frost (32°F) in Jamestown is May 8. There is still a 10% chance of frost until May 21.
When can I plant tomatoes in Jamestown?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around May 15 – May 22. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Jamestown State Hosp, ND (USC00324418), 3.4 km (2.1 mi) from the city center, elevation 447 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.