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Hardiness Zones -- Details
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Zones 2-10 in the map have been subdivided into light- and dark-colored sections
(a and b) that represent 5 F (2.8 C) differences within the 10 F (5.6 C)
zone. The light color of each zone represents the colder section;
the dark color, the warmer section. Zone 11 represents any area where
the average annual minimum temperature is above 40 F (4.4 C).
The map shows 20 latitude and longitude lines. Areas above an arbitrary elevation
are traditionally considered unsuitable for plant cropping and do not bear
appropriate zone designations. There are also island zones that,
because of elevation differences, are warmer or cooler than the surrounding
areas and are given a different zone designation.
Note that many large urban areas carry a warmer zone designation than the surrounding
countryside. The map-contains as much detail as possible, considering
the vast amount of data on which it is based and its size.
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USDA Hardiness Zones and Average Annual Minimum Temperature Range
|
1 |
Below -50 F
|
Below -45.6 C
|
Fairbanks,
Alaska; Resolute, Northwest Territories (Canada) |
|
2a |
-50
to -45 F
|
-42.8
to -45.5 C |
Prudhoe
Bay, Alaska; Flin Flon, Manitoba (Canada) |
|
2b |
-45
to -40 F
|
-40.0
to -42.7 C |
Unalakleet,
Alaska; Pinecreek, Minnesota |
|
3a |
-40
to -35 F
|
-37.3
to -39.9 C |
International
Falls, Minnesota; St. Michael, Alaska |
|
3b |
-35
to -30 F
|
-34.5
to -37.2 C |
Tomahawk,
Wisconsin; Sidney, Montana |
|
4a |
-30
to -25 F
|
-31.7
to -34.4 C |
Minneapolis/St.Paul,
Minnesota; Lewistown, Montana |
|
4b |
-25
to -20 F
|
-28.9
to -31.6 C |
Northwood,
Iowa; Nebraska |
|
5a |
-20
to -15 F
|
-26.2
to -28.8 C |
Des
Moines, Iowa; Illinois |
|
5b |
-15
to -10 F
|
-23.4
to -26.1 C |
Columbia,
Missouri; Mansfield, Pennsylvania |
|
6a |
-10
to -5 F
|
-20.6
to -23.3 C |
St.
Louis, Missouri; Lebanon, Pennsylvania |
|
6b |
-5
to 0 F
|
-17.8
to -20.5 C |
McMinnville,
Tennessee; Branson, Missouri |
|
7a |
0
to 5 F
|
-15.0
to -17.7 C |
Oklahoma
City, Oklahoma; South Boston, Virginia |
|
7b |
5
to 10 F
|
-12.3
to -14.9 C |
Little
Rock, Arkansas; Griffin, Georgia |
|
8a |
10
to 15 F
|
-9.5
to -12.2 C |
Tifton,
Georgia; Dallas, Texas |
|
8b |
15
to 20 F
|
-6.7
to -9.4 C |
Austin,
Texas; Gainesville, Florida |
|
9a |
20
to 25 F
|
-3.9
to -6.6 C |
Houston,
Texas; St. Augustine, Florida |
|
9b |
25
to 30 F
|
-1.2
to -3.8 C |
Brownsville,
Texas; Fort Pierce, Florida |
|
10a |
30
to 35 F
|
1.6
to -1.1 C |
Naples,
Florida; Victorville, California |
|
10b |
35
to 40 F
|
4.4
to 1.7 C |
Miami,
Florida; Coral Gables, Florida |
|
11 |
above
40 F
|
above
4.5 C |
Honolulu,
Hawaii; Mazatlan, Mexico |
USDA
Miscellaneous Publication No. 1475. Issued January 1990.
Authored
by Henry M. Cathey while Director, U.S. National Arboretum
Edited,
formatted and prepared for the US National Arboretum web site by Ramon
Jordan, March 1998 & Revised March 2001; January 2003
U.S. National Arboretum, Agricultural Research Service, U.S. Department of Agriculture,
Washington, DC 20002
Note:
This publication is not copyrighted, and permission to reproduce all or
any part of it is not required.
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