Do you know your hardiness zone?
Posted by: TinyRoots / Admin on Jul 16, 2009
The U.S. Department of Agriculture (USDA) zone system is based on minimum winter temperatures. This system consists of zones 1-11, zone 1 having the coldest winter temperatures and zone 11 having the warmest.
For plants that will grow inside your home, Hardiness Zones become far less important. Unless you turn the heat off during the winter, it's unlikely that the temperature will ever drop below Zone 11 (40 degrees Fahrenheit / 4.4 degrees Celsius).
As this is a U.S. government agency, they didn't think to include other countries, but our Canadian visitors can simply use the temperature guides below to find out their USDA Zone.
Remember, the Hardiness Zones is only a guide.
USDA Hardiness Zones and Average Annual Minimum Temperature Range
|
Zone |
Fahrenheit |
Celsius |
|
1 |
Below -50 F |
Below -45.6 C |
|
2a |
-50 to -45 F |
-42.8 to -45.5 C |
|
2b |
-45 to -40 F |
-40.0 to -42.7 C |
|
3a |
-40 to -35 F |
-37.3 to -39.9 C |
|
3b |
-35 to -30 F |
-34.5 to -37.2 C |
|
4a |
-30 to -25 F |
-31.7 to -34.4 C |
|
4b |
-25 to -20 F |
-28.9 to -31.6 C |
|
5a |
-20 to -15 F |
-26.2 to -28.8 C |
|
5b |
-15 to -10 F |
-23.4 to -26.1 C |
|
6a |
-10 to -5 F |
-20.6 to -23.3 C |
|
6b |
-5 to 0 F |
-17.8 to -20.5 C |
|
7a |
0 to 5 F |
-15.0 to -17.7 C |
|
7b |
5 to 10 F |
-12.3 to -14.9 C |
|
8a |
10 to 15 F |
-9.5 to -12.2 C |
|
8b |
15 to 20 F |
-6.7 to -9.4 C |
|
9a |
20 to 25 F |
-3.9 to -6.6 C |
|
9b |
25 to 30 F |
-1.2 to -3.8 C |
|
10a |
30 to 35 F |
1.6 to -1.1 C |
|
10b |
35 to 40 F |
4.4 to 1.7 C |
|
11 |
above 40 F |
above 4.5 C |
Source: U.S. National Arboretum
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