USDA hardiness zone 4a
USDA plant hardiness zone 4a covers areas whose average annual extreme minimum winter temperature is −30 to −25 °F — the standard USDA measure of which perennials survive an average winter. Hardiness zone sets winter survival, but planting DATES depend on your local frost calendar, which varies within a zone. 274 locations on this site fall in zone 4a (Aberdeen, SD, Aitkin, MN, Alakanuk, AK, Aleknagik, AK, Almont, ND, Amasa, MI, Argusville, ND, Argyle, MN, and 266 more); open one to see its frost dates, growing-season length, and a printable per-crop planting calendar.
Locations in zone 4a — 60 of 274
| Location | Last frost | First frost | Season (days) |
|---|---|---|---|
| Aberdeen, SD | May 9 | Sep 26 | 139 |
| Almont, ND | May 17 | Sep 21 | 124 |
| Bainville, MT | May 21 | Sep 20 | 120 |
| Beecher Falls, VT | May 25 | Sep 24 | 121 |
| Birchwood, WI | May 8 | Oct 2 | 145 |
| Brady, MT | May 20 | Sep 19 | 119 |
| Cannon Ball, ND | May 12 | Sep 27 | 136 |
| Carrington, ND | May 12 | Sep 27 | 137 |
| Chelsea, SD | May 11 | Sep 27 | 137 |
| Cokeville, WY | May 19 | Sep 21 | 123 |
| Covington, MI | May 23 | Oct 1 | 128 |
| Crookston, MN | May 11 | Sep 27 | 138 |
| Derby Line, VT | May 14 | Sep 30 | 138 |
| Driscoll, ND | May 15 | Sep 25 | 133 |
| Eagle Lake, ME | Jun 2 | Sep 15 | 102 |
| Exeland, WI | May 19 | Sep 27 | 129 |
| Fergus Falls, MN | May 4 | Oct 5 | 152 |
| Finlayson, MN | May 13 | Sep 29 | 137 |
| Fort Benton, MT | May 15 | Sep 22 | 129 |
| Frazer, MT | May 16 | Sep 20 | 125 |
| Glasgow, MT | May 3 | Oct 1 | 151 |
| Grand Forks, ND | May 10 | Oct 1 | 144 |
| Grenora, ND | May 19 | Sep 17 | 121 |
| Hartsel, CO | Jun 2 | Sep 19 | 108 |
| Hibbing, MN | Jun 5 | Sep 8 | 93 |
| Igiugig, AK | May 10 | Oct 1 | 144 |
| Island Park, ID | Jun 15 | Sep 10 | 87 |
| Jordan, MT | May 18 | Sep 20 | 123 |
| Killdeer, ND | May 21 | Sep 23 | 124 |
| Ladysmith, WI | May 7 | Oct 3 | 147 |
| Leeds, ND | May 15 | Sep 27 | 133 |
| Linton, ND | May 12 | Sep 29 | 138 |
| Lodge Pole, MT | May 18 | Sep 23 | 126 |
| Long Prairie, MN | May 13 | Sep 27 | 134 |
| Mahtowa, MN | May 12 | Oct 2 | 144 |
| Manning, ND | May 12 | Sep 28 | 138 |
| Max, ND | May 10 | Sep 28 | 141 |
| Medora, ND | May 19 | Sep 20 | 123 |
| Michigamme, MI | Jun 5 | Sep 10 | 96 |
| Mohall, ND | May 17 | Sep 23 | 127 |
| Nashua, MN | May 1 | Oct 9 | 160 |
| Oliver, WI | Jun 1 | Sep 22 | 113 |
| Parishville, NY | May 16 | Sep 28 | 134 |
| Pine, MN | May 11 | Oct 1 | 141 |
| Pollock, SD | May 8 | Sep 30 | 143 |
| Regan, ND | May 8 | Oct 1 | 145 |
| Rice Lake, MN | May 21 | Sep 27 | 129 |
| Rocky Boy West, MT | May 17 | Sep 25 | 128 |
| Shell Lake, WI | May 14 | Sep 28 | 135 |
| South Browning, MT | Jun 8 | Sep 5 | 88 |
| Stanley, ND | May 17 | Sep 23 | 127 |
| Sunset Colony, SD | May 13 | Sep 26 | 135 |
| Terry, MT | May 8 | Sep 30 | 144 |
| Three Lakes, MI | May 31 | Sep 22 | 115 |
| Tuntutuliak, AK | May 21 | Sep 22 | 122 |
| Velva, ND | May 22 | Sep 22 | 123 |
| Walcott, ND | May 6 | Sep 29 | 145 |
| Watersmeet, MI | May 25 | Sep 24 | 121 |
| West Glendive, MT | May 3 | Oct 4 | 153 |
| Wibaux, MT | May 27 | Sep 16 | 112 |
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.
What zone 4a means for your garden
A plant rated "hardy to zone 4a" can be expected to survive a winter whose coldest night lands in the −30 to −25 °F range — the metric the USDA map is built on. That governs perennials, shrubs, and trees. For annual vegetables, what matters is the frost calendar: the dates of the average last spring and first fall freeze, which set when it is safe to plant and how long the season runs. Those come from the individual location pages above.
Zones are from the USDA Plant Hardiness Zone Map 2023, matched to each location's ZIP — see the methodology page. Browse all hardiness zones or crop-by-crop timing.
Frequently asked questions
- What temperature range is USDA zone 4a?
- Zone 4a covers areas whose average annual extreme minimum winter temperature is −30 to −25 °F. Each numbered zone is a 10°F band; the "a" and "b" half-zones split it into 5°F steps.
- Does zone 4a tell me when to plant?
- No — the hardiness zone tells you which perennials survive winter, not when to sow annual vegetables. Planting dates depend on your local last and first frost, which can vary within a single zone. Open one of the sample locations in zone 4a to see its frost calendar and per-crop planting windows.
- What can I grow in zone 4a?
- Almost any common vegetable can be grown in zone 4a; what changes with zone and local climate is the timing and the length of the season. Cold-hardy crops (peas, spinach, lettuce) go out earliest, tender crops (tomatoes, peppers, basil) after the last frost. Use each location's calendar for exact dates.