Where zone 4b shows up
| Location | Zone | Last spring frost | First fall frost | Frost-free days |
|---|---|---|---|---|
| Bismarck, ND | 4b | May 10 | Sep 30 | 143 |
| Caribou, ME | 4b | May 7 | Oct 1 | 147 |
| Rochester, MN | 4b | May 2 | Oct 7 | 158 |
| Great Falls, MT | 4b | May 17 | Sep 24 | 130 |
| Butte, MT | 4b | Jun 5 | Sep 11 | 98 |
| Brookings, SD | 4b | May 5 | Oct 2 | 150 |
States with zone 4b ground
Bottom line: zone 4b tells you what will survive your
winter. It does not tell you when to plant — two zone-4b gardens in this list are
34 days apart on last frost.
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