Laffodils Landscaping

 

 

Plant Hardiness Zones -- Details

 Plant Hardiness Zones Table 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.

USDA Hardiness Zones and Average Annual Minimum Temperature Range

  Zone  
  Fahrenheit  
    Celsius    
  Example Cities  
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
 

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