Selecting a Winning Site and Crops to Match - Growing Organic Orchard Fruits - page 18

USDA PLANT HARDINESS ZONE MAP
The map (see below and available online) divides the United States into
13 hardiness zones based on average minimum winter temperatures.
While other hardiness zone systems have been published, the USDA
map is the most comprehensive and universal for North America.
This updated map, released in January 2012, expands from 11 to 13
hardiness zones and updates the zones based on recent weather data.
Unfortunately,the2012editiondoesnotincludeCanada,asearlierver-
sions of the map did. For Canadian growers, the 1990 version of the
map is still available for downloading on the USDA site under the tab
“Map and Data Downloads.” (see Resources ➔ ). The zones may have
shifted slightly but will still give you a starting point for selecting crops
and varieties. In general, you may find that your location would now be
rated about one-half zone warmer than previously.
The new map is based on 30 years of temperature data, rather than
13 years used for the original map. Also, it turns out that the original
13-year period was unusually cold. Hardiness zone classifications in
the new map tend to be slightly warmer than under the original map for
many locations.
Fruit trees are typically rated for a range of hardiness zones. 'Harglow'
apricot, for example, is recommended for hardiness Zones 5 to 8 and
is well suited for orchards from the mid-southern United States into
Canada. At the other extreme, tropical and subtropical loquat trees are
rated to Zones 8 to 12 and are grown commercially and in home orch-
ards in the United States in the warmer parts of Florida, coastal Geor-
gia, Hawaii, and southern California.