Hardiness Ratings Explained

US Gardeners: the Unites States Department of Agriculture (USDA) provides the following information, including maps, for the country as a whole, or on a state-bystate basis. Click the following links to open a new window as appropriate.

USDA Hardiness Zones Home Page: http://www.usna.usda.gov/Hardzone/ushzmap.html

By State: AK  AL  AR  AZ  CA  CO  CT  DC  DE  FL  GA  HI  IA  ID  IL  IN  KS  KY LA  MA  MD  ME  MI  MN  MO  MS  MT  NC  ND  NE  NH  NJ  NM  NV  NY OH  OK  OR  PA  RI  SC  SD  TN  TX  UT  VA  VT  WA  WI  WV  WY

Canadian Gardeners: Agriculture Canada have a detailed interactive easy to use map, together with a range of Canadian specific information.

English Version

French Version

Australian Gardeners: Ian Dawson of the Australian National Botanic Gardens has produced an adaptation of the US Zones for Australia.

http://www.anbg.gov.au/hort.research/zones.html

British Gardeners: the following US zones approximately apply to the British Isles.

Zone

6
7
8
9
10

Range °C

  -23.3 to -17.8
  -17.7 to -12.3
  -12.2 to  -6.7
   -6.6 to  -1.2
   -1.7 to  +4.4

Range °F

 -10 to 0
   0 to 10
  10 to 20
  20 to 30
  30 to 40