|
Zone
|
Temperature
|
Notes |
|
1
|
Below
-50
|
|
|
2
|
-50
to -40
|
|
|
3
|
-40
to -30
|
|
|
4
|
-30
to -20
|
Soil
freezes solidly and deeply from late fall through early spring |
|
5
|
-20
to -10
|
Soil
freezes more deeply for the winter |
|
6
|
-10
to 0
|
Soil
will only freeze down 1 to 3 inches for a few weeks at a time |
|
7
|
0
to 10
|
Soil
rarely freezes more than just below the surface |
|
8
|
10
to 20
|
|
|
9
|
20
- 30
|
|
|
10
|
30
- 40
|
|
|
11
|
Above
40
|
