USDA hardiness zone 3b
USDA plant hardiness zone 3b covers areas whose average annual extreme minimum winter temperature is −35 to −30 °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. 85 locations on this site fall in zone 3b (Adams, ND, Akiachak, AK, Alamo, ND, Babbitt, MN, Balta, ND, Bantry, ND, Baudette, MN, Belcourt, ND, and 77 more); open one to see its frost dates, growing-season length, and a printable per-crop planting calendar.
Locations in zone 3b — 60 of 85
| Location | Last frost | First frost | Season (days) |
|---|---|---|---|
| Adams, ND | May 15 | Sep 22 | 128 |
| Akiachak, AK | May 21 | Sep 22 | 122 |
| Alamo, ND | May 18 | Sep 20 | 124 |
| Balta, ND | May 17 | Sep 23 | 129 |
| Bantry, ND | May 15 | Sep 25 | 132 |
| Belcourt, ND | May 19 | Sep 24 | 126 |
| Bemidji, MN | May 17 | Sep 26 | 131 |
| Big Falls, MN | May 24 | Sep 20 | 117 |
| Cando, ND | May 15 | Sep 27 | 133 |
| Central, AK | May 25 | Aug 26 | 92 |
| Cook, MN | Jun 1 | Sep 15 | 104 |
| Eagle Lake, ME | May 30 | Sep 13 | 106 |
| Effie, MN | May 14 | Oct 2 | 140 |
| Egeland, ND | May 18 | Sep 23 | 127 |
| Ester, AK | May 15 | Sep 16 | 122 |
| Federal Dam, MN | May 8 | Oct 1 | 144 |
| Finland, MN | May 15 | Oct 1 | 137 |
| Fortuna, ND | May 19 | Sep 17 | 121 |
| Fosston, MN | May 15 | Sep 26 | 132 |
| Gildford, MT | May 24 | Sep 15 | 114 |
| Greenbush, MN | May 20 | Sep 17 | 118 |
| Grenora, ND | May 16 | Sep 18 | 125 |
| Grygla, MN | May 24 | Sep 20 | 120 |
| Hallock, MN | May 8 | Sep 30 | 142 |
| Healy, AK | Jun 6 | Aug 25 | 77 |
| Healy Lake, AK | Jun 5 | Aug 21 | 75 |
| Hibbing, MN | Jun 5 | Sep 8 | 93 |
| Hinsdale, MT | May 15 | Sep 26 | 132 |
| Hoyt Lakes, MN | May 27 | Sep 23 | 117 |
| Lancaster, MN | May 16 | Sep 29 | 137 |
| Littlefork, MN | May 23 | Sep 21 | 118 |
| Livengood, AK | Jun 1 | Aug 28 | 87 |
| Lutsen, MN | May 22 | Oct 9 | 136 |
| Lutsen, MN | May 26 | Sep 27 | 126 |
| Meadowlands, MN | May 29 | Sep 18 | 111 |
| Mountain Iron, MN | May 12 | Oct 1 | 141 |
| Northome, MN | May 16 | Sep 26 | 131 |
| Opheim, MT | Jun 5 | Sep 2 | 89 |
| Opheim, MT | Jun 1 | Sep 7 | 99 |
| Outlook, MT | May 19 | Sep 23 | 125 |
| Park Rapids, MN | May 14 | Sep 25 | 133 |
| Plentywood, MT | May 25 | Sep 14 | 111 |
| Plummer, MN | May 9 | Sep 30 | 142 |
| Ponemah, MN | May 12 | Oct 4 | 142 |
| Ranier, MN | May 29 | Sep 13 | 109 |
| Redstone, MT | May 28 | Sep 7 | 101 |
| Rolette, ND | May 22 | Sep 20 | 120 |
| Rolla, ND | May 20 | Sep 26 | 128 |
| Scobey, MT | May 28 | Sep 6 | 99 |
| Sherwood, ND | May 17 | Sep 23 | 127 |
| Sleeping Buffalo, MT | May 15 | Sep 23 | 130 |
| Stebbins, AK | Jun 5 | Sep 3 | 88 |
| Taconite, MN | May 17 | Sep 24 | 130 |
| Tioga, ND | May 11 | Sep 26 | 136 |
| Towner, ND | May 17 | Sep 22 | 126 |
| Warroad, MN | May 16 | Sep 24 | 129 |
| Whitewater, MT | May 19 | Sep 22 | 124 |
| Willow, AK | May 29 | Sep 7 | 100 |
| Winton, MN | May 24 | Sep 23 | 121 |
| Winton, MN | May 14 | Sep 29 | 135 |
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 3b means for your garden
A plant rated "hardy to zone 3b" can be expected to survive a winter whose coldest night lands in the −35 to −30 °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 3b?
- Zone 3b covers areas whose average annual extreme minimum winter temperature is −35 to −30 °F. Each numbered zone is a 10°F band; the "a" and "b" half-zones split it into 5°F steps.
- Does zone 3b 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 3b to see its frost calendar and per-crop planting windows.
- What can I grow in zone 3b?
- Almost any common vegetable can be grown in zone 3b; 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.