USDA zone 4a in North Dakota
USDA plant hardiness zone 4a covers 94 locations across North Dakota (average annual extreme minimum −30 to −25 °F): Almont, ND, Argusville, ND, Beach, ND, Bergen, ND, Beulah, ND, Bismarck, ND, and 88 more. Average last spring frost across this group ranges May 2 (Hillsboro) to May 23 (Taylor), and growing seasons run 119–158 days (Powers Lake to Hillsboro) — even within one state, because hardiness sets winter survival, not planting dates. The table below gives every North Dakota location's own frost dates; the printable planting calendar uses Turtle Lake, this group's median-season location.
- USDA zone
- 4a−30 to −25 °F
- Last frost range
- May 2–May 23avg, 32°F
- First frost range
- Sep 17–Oct 9avg, 32°F
- Growing season range
- 119–158days
Locations in this group
Every location below shares this zone and a nearby weather station, but keeps its own frost dates — find your town for its own numbers, or use the ZIP planner on the home page for an instant personalized answer.
| Location | Also covers | Nearest station | Last frost | First frost | Season (days) |
|---|---|---|---|---|---|
| Almont | — | Almont | May 17 | Sep 21 | 124 |
| Argusville | Georgetown, Felton, Gardner, Perley, Grandin | Georgetown 1 E | May 9 | Oct 1 | 143 |
| Beach | — | Trotters 3 Sse | May 15 | Sep 25 | 132 |
| Bergen | Balfour, Ruso, Butte | Butte 5se | May 16 | Sep 28 | 134 |
| Beulah | Hazen, Zap, Golden Valley, Dodge | Beulah 1 W | May 21 | Sep 20 | 121 |
| Bismarck | Menoken, Lincoln, Wilton, Solen | Bismarck | May 14 | Sep 27 | 136 |
| Cannon Ball | Hazelton, Braddock | Hazelton 4nw | May 12 | Sep 27 | 136 |
| Carpio | — | Foxholm 7 N | May 11 | Sep 29 | 138 |
| Carrington | New Rockford, Sykeston, Woodworth, Cathay | Carrington 4 N | May 12 | Sep 27 | 137 |
| Center | — | Center 4se | May 11 | Sep 29 | 140 |
| Crary | — | Devils Lake Kdlr | May 6 | Oct 5 | 152 |
| Crosby | Ambrose | Crosby | May 17 | Sep 23 | 128 |
| Devils Lake | — | Devils Lake | May 12 | Sep 30 | 141 |
| Drake | Karlsruhe, Anamoose | Drake 9 Ne | May 12 | Sep 27 | 137 |
| Drayton | — | Pembina | May 16 | Sep 29 | 137 |
| Driscoll | Steele, Dawson, Tuttle, Pettibone, Robinson | Steele 4n | May 15 | Sep 25 | 133 |
| Elgin | — | Heart Butte Dam | May 14 | Sep 29 | 136 |
| Enderlin | Alice, Kathryn, Nome, Sheldon | Enderlin 2w | May 3 | Oct 5 | 155 |
| Epping | — | Williston Sloulin Intl Ap | May 21 | Sep 21 | 123 |
| Fairmount | Mooreton | Victor 4 N | May 4 | Oct 3 | 152 |
| Fargo | Moorhead, West Fargo, Horace, Hawley, Glyndon, Harwood, +5 more | Fargo Hector Intl Ap | May 10 | Sep 30 | 143 |
| Fessenden | Bowdon | Fessenden | May 13 | Sep 28 | 139 |
| Finley | Sharon, Cooperstown, Jessie, Dazey, Luverne, Hannaford | Cooperstown | May 17 | Sep 23 | 128 |
| Flasher | Raleigh, Porcupine | Flasher | May 13 | Sep 27 | 135 |
| Fort Totten | Maddock, Minnewaukan, Churchs Ferry, Oberon, Sheyenne | Minnewaukan | May 12 | Sep 29 | 138 |
| Gackle | — | Gackle | May 6 | Oct 4 | 150 |
| Gladstone | — | Dickinson | May 20 | Sep 22 | 123 |
| Grafton | — | Grafton | May 4 | Oct 7 | 156 |
| Grand Forks | East Grand Forks, Reynolds, Thompson | Grand Forks Univ (nws) | May 10 | Oct 1 | 144 |
| Grand Forks | Grand Forks AFB, Ardoch, Emerado, Manvel, Gilby | Grand Forks Intl Ap | May 16 | Sep 27 | 133 |
| Granville | — | Granville | May 9 | Oct 1 | 145 |
| Grenora | — | Fortuna 1 W | May 19 | Sep 17 | 121 |
| Gwinner | Forman, Rutland, Havana, Cogswell | Forman 5 Sse | May 7 | Oct 1 | 146 |
| Halliday | Dunn Center | Dunn Ctr 1e | May 20 | Sep 21 | 125 |
| Harvey | Esmond, Martin | Harvey 4ne | May 12 | Sep 26 | 135 |
| Hebron | Glen Ullin | Hebron | May 19 | Sep 21 | 123 |
| Hillsboro | Caledonia, Buxton, Nielsville, Blanchard | Hillsboro 3 N | May 2 | Oct 9 | 158 |
| Hurdsfield | — | Tuttle 12nne | May 13 | Sep 29 | 139 |
| Jamestown | Ypsilanti | Jamestown State Hosp | May 8 | Sep 29 | 143 |
| Kenmare | Bowbells, Donnybrook, Lignite | Kenmare 1 Wsw | May 15 | Sep 23 | 129 |
| Kensal | Pingree | Edmunds Arrowwood Ref | May 11 | Sep 28 | 139 |
| Killdeer | — | Killdeer | May 21 | Sep 23 | 124 |
| Knox | Balta, York | Rugby | May 17 | Sep 23 | 129 |
| Lawton | Hampden, Starkweather | Edmore 4nw | May 15 | Sep 22 | 128 |
| Leeds | — | Leeds | May 15 | Sep 27 | 133 |
| Leith | New Leipzig | Pretty Rock | May 20 | Sep 23 | 124 |
| Linton | — | Linton | May 12 | Sep 29 | 138 |
| Lisbon | Gwinner, Englevale | Lisbon | May 12 | Sep 27 | 136 |
| Litchville | Verona | La Moure | May 10 | Sep 28 | 140 |
| Mandan | — | Mandan Exp Stn | May 13 | Sep 27 | 136 |
| Mandaree | Parshall, Four Bears | Keene 3s | May 20 | Sep 20 | 121 |
| Manning | — | Fairfield | May 12 | Sep 28 | 138 |
| Manning | — | Dickinson Rch Hq | May 18 | Sep 24 | 127 |
| Mantador | — | Lidgerwood | May 2 | Oct 6 | 157 |
| Marmarth | — | Baker Muni Ap | May 16 | Sep 26 | 132 |
| Max | Makoti, Douglas, Benedict | Max | May 10 | Sep 28 | 141 |
| Mayville | Portland, Hatton, Clifford | Mayville | May 13 | Sep 27 | 136 |
| Medina | Tappen, Streeter | Streeter 5 Nw | May 13 | Sep 30 | 139 |
| Medora | Golva | Medora | May 19 | Sep 20 | 123 |
| Minot | Des Lacs, Sawyer | Minot Exp Stn | May 13 | Sep 27 | 136 |
| Minot | Minot AFB, Surrey, Berthold, Des Lacs, Glenburn, Ruthville | Minot Intl Ap | May 10 | Oct 1 | 144 |
| Mohall | Lansford, Tolley | Mohall | May 17 | Sep 23 | 127 |
| Mott | — | Mott | May 16 | Sep 25 | 129 |
| Napoleon | — | Napoleon | May 13 | Sep 28 | 136 |
| New Salem | — | New Salem 5nw | May 18 | Sep 24 | 127 |
| Northwood | — | Larimore 4sw | May 11 | Sep 28 | 139 |
| Oakes | — | Oakes | May 8 | Sep 28 | 144 |
| Page | Hope, Pillsbury, Galesburg | Colgate | May 10 | Sep 24 | 136 |
| Park River | McVille, Petersburg, Fordville, Lakota, Aneta, Inkster, +8 more | Petersburg 2 N | May 11 | Sep 28 | 138 |
| Powers Lake | — | Powers Lake 1n | May 18 | Sep 17 | 119 |
| Regan | Denhoff, Wing, Goodrich | Mc Clusky | May 8 | Oct 1 | 145 |
| Regent | — | New England | May 16 | Sep 24 | 128 |
| Richardton | — | Richardton Abbey | May 9 | Oct 1 | 145 |
| Solen | — | Breien | May 12 | Sep 24 | 134 |
| Spiritwood | Wimbledon, Courtenay | Jamestown Muni Ap | May 11 | Sep 28 | 138 |
| Stanley | Palermo, Plaza, Ross | Stanley 3 Nnw | May 17 | Sep 23 | 127 |
| Taylor | Dodge | Taylor 7 Nnw | May 23 | Sep 20 | 119 |
| Tolna | Warwick, Binford, Pekin, McHenry, Grace, Sutton, +1 more | Mc Henry 3w | May 12 | Sep 28 | 139 |
| Turtle Lake * | Mercer | Turtle Lake | May 14 | Sep 26 | 136 |
| Valley | Tower, Rogers, Sanborn, Oriska | Valley City 3 Nnw | May 13 | Sep 26 | 136 |
| Velva | — | Velva | May 22 | Sep 22 | 123 |
| Wahpeton | Breckenridge, Dwight | Breckenridge 3e | May 4 | Oct 3 | 152 |
| Walcott | Colfax, Milnor, Wyndmere, McLeod, Mooreton, Barney | Mc Leod 3 E | May 6 | Sep 29 | 145 |
| Walhalla | St. Thomas, Cavalier, Crystal, Hoople, Neche, Edinburg, +3 more | Cavalier 7nw | May 12 | Sep 30 | 139 |
| Washburn | Underwood, Stanton, Coleharbor | Underwood | May 10 | Sep 29 | 139 |
| Watford | — | Grassy Butte 2ene | May 18 | Sep 23 | 125 |
| Watford | Alexander, Arnegard | Watford City | May 9 | Sep 27 | 139 |
| Wheatland | Casselton, Erie, Arthur, Hunter, Amenia, Kindred, +4 more | Casselton Agronomy Farm | May 9 | Oct 1 | 143 |
| White Earth | Ray | Tioga 1e | May 11 | Sep 26 | 136 |
| White Shield | Riverdale, Ryder | Garrison | May 14 | Sep 26 | 133 |
| Williston | Trenton | Williston Exp Farm | May 13 | Sep 26 | 135 |
| Wilton | — | Wilton | May 11 | Sep 30 | 142 |
| Wishek | — | Wishek | May 13 | Sep 27 | 135 |
| Zeeland | — | Ashley | May 13 | Sep 28 | 137 |
* Turtle Lake is this group's median-season location — the calendar below is computed from its data.
Data: NOAA NCEI U.S. Climate Normals 1991–2020 (public domain) and USDA Plant Hardiness Zone Map 2023. Planting windows synthesized from U.S. Cooperative Extension guides.
Planting calendar (Turtle Lake, representative)
Computed from Turtle Lake's average frost dates — the median-season location in this North Dakotazone 4a group. hatched = start seeds indoors, solid green = plant out, teal = a fall sowing, and the terracotta dot marks the estimated first harvest. Ranges are extension-guide planning guidance, not guarantees — your own location's dates may run a week or two earlier or later (see the table above).
- Start indoors
- Plant out
- Fall sowing
- First harvest
| Crop | Frost tolerance | Start indoors | Plant out | First harvest | Fall planting | Season fit |
|---|---|---|---|---|---|---|
| Tomato | Tender | Mar 19 – Apr 2 | May 21 – May 28 | Jul 20 – Aug 9 | — | matures comfortably |
| Pepper | Very tender | Mar 5 – Mar 19 | May 28 – Jun 4 | Jul 27 – Aug 26 | — | matures comfortably |
| Cucumber | Tender | Apr 16 – Apr 23 | May 21 – May 28 | Jul 10 – Jul 30 | — | matures comfortably |
| Summer squash / zucchini | Tender | — | May 21 – May 28 | Jul 5 – Jul 20 | — | matures comfortably |
| Bush bean | Tender | — | May 21 – May 28 | Jul 10 – Jul 20 | Jul 28 – Aug 7 | matures comfortably |
| Sweet corn | Tender | — | May 14 – May 28 | Jul 13 – Aug 12 | — | matures comfortably |
| Basil | Very tender | Apr 2 – Apr 16 | May 21 – May 28 | Jun 20 – Jul 5 | — | matures comfortably |
| Lettuce | Half-hardy | Apr 2 – Apr 16 | Apr 16 – Apr 30 | May 31 – Jun 15 | Jul 14 – Jul 29 | matures comfortably |
| Pea | Hardy | — | Apr 2 – Apr 16 | May 27 – Jun 11 | Jul 4 – Jul 19 | matures comfortably |
| Spinach | Hardy | — | Apr 2 – Apr 16 | May 12 – May 22 | Jul 24 – Aug 3 | matures comfortably |
| Carrot | Half-hardy | — | Apr 23 – Apr 30 | Jun 22 – Jul 12 | Jun 24 – Jul 14 | matures comfortably |
| Broccoli | Half-hardy | Mar 19 – Apr 2 | Apr 16 – Apr 30 | Jun 10 – Jun 30 | Jun 29 – Jul 19 | matures comfortably |
Which crops fit this growing season
Using Turtle Lake's own 136-day growing season (32°F, NOAA 1991–2020 median) against each crop's real days-to-maturity range: 12 of 12 crops mature here with comfortable margin. A different location in the table above with a longer or shorter season will get a different mix — the ZIP planner on the home page gives your own.
Frost & freeze dates (Turtle Lake)
From NOAA's 1991–2020 Climate Normals at station USC00328840. The median (p50) is the average date; the 90%-safe column is the date the freeze has passed in about 9 years out of 10 — the conservative date to plant after or harvest before.
| Threshold | Last spring — avg | Last spring — 90%-safe | First fall — avg | First fall — 90%-safe | Season (days) |
|---|---|---|---|---|---|
| 36°F | May 24 | Jun 4 | Sep 19 | Sep 30 | 118 |
| 32°F (freeze) | May 14 | May 26 | Sep 26 | Oct 9 | 136 |
| 28°F | May 5 | May 18 | Oct 5 | Oct 20 | 155 |
| 24°F | Apr 27 | May 9 | Oct 15 | Oct 29 | 173 |
Growing degree days
Growing degree days (GDD) accumulate warmth above a base temperature over the year — a better predictor of crop development than the calendar alone. This group's median GDD (base 50°F) across all 94 locations is 2,148; Turtle Lake's own reading is shown below.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 2,112 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 3,849 | cool-season crops (brassicas, greens) |
Hardiness zone 4a in North Dakota
Zone 4a means an average annual extreme minimum winter temperature of about −30 to −25 °F on the USDA's 2023 map — the number that tells you which perennials, shrubs, and trees reliably survive an average winter here. It does not set your planting dates, which come from the frost calendar above. North Dakota spans 3 hardiness zones in this dataset — see all North Dakota locations for the full range, including zones3b, 4b.
Explore zone 4a in other states at zone 4a, or see all USDA hardiness zones.
Frequently asked questions
- What does USDA hardiness zone 4a mean in North Dakota?
- Zone 4a means an average annual extreme minimum winter temperature of −30 to −25 °F — the standard USDA measure of which perennials survive winter. 94 locations in North Dakota fall in this zone. It does not set planting dates; see the frost calendar below for that.
- Where in North Dakota's zone 4a is the growing season longest?
- Hillsboro runs the longest season on this page at about 158 days; Powers Lake is shortest at about 119 days — they share the same hardiness zone, but they sit at different weather stations, so their frost calendars differ.
- When should I plant tomatoes in North Dakota's zone 4a?
- Using Turtle Lake's frost dates (this page's median-season location): start seeds indoors about Mar 19 – Apr 2, then transplant outside about May 21 – May 28. Your own location in the table above may differ by a week or two — use the ZIP planner on the home page for your exact station's dates.
- Does every location in North Dakota's zone 4a have the same frost dates?
- No — they do not all share a weather station, so frost dates vary by a week or more across the 94 locations listed (see the table above for each location's own dates).
Sources & method
Frost, freeze, growing-season, and growing-degree-day figures are NOAA NCEI U.S. Climate Normals 1991–2020, one reading per location's own nearest station (see the table above). The hardiness zone is the USDA Plant Hardiness Zone Map 2023, matched to each location's ZIP. Planting windows are computed by counting from the average last and first frost using per-crop offsets synthesized from U.S. Cooperative Extension guides — the full method and citations are on the methodology page.