JungleSeeds
JungleSeeds&Gardens - Specialists in Exotic Seeds & Plants
USA Zone Classification
As most of you know the USA use a zone classification for plant cold hardiness, please remember that these only give a rough guide to hardiness in the UK. The USA has higher summer temperatures to harden plants and often only short spells of frost rather than long cold dark damp winters in the UK. However you may find this useful as we are approximately in the range 7a to 8b in England.
| USDA Zone | Temperature Range |
| 1 | Below -50 F |
| (below -45.6C) | |
| 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) |