How to Use Hardiness Zone Information
Each Zone in the system represents a region of minimum average winter temperatures. The lower the Zone number, the colder the region. Although factors other than temperature affect the ability of a plant to survive, the Zone system is a reasonable starting point for many gardeners.
The chart below shows the temperature ranges associated with the Zone system. In this chart, the Zones are divided into A and B regions, which are sometimes used to fine-tune plant recommendations.
| Zone | Average Minimum Winter Temp. | Example Cities | |
| 1 | Below -50 F | Fairbanks, Alaska; Resolute, Northwest Territories (Canada) | |
| 2a | -50 to -45 F | Prudhoe Bay, Alaska; Flin Flon, Manitoba (Canada) | |
| 2b | -45 to -40 F | Unalakleet, Alaska; Pinecreek, Minnesota | |
| 3a | -40 to -35 F | International Falls, Minnesota; St. Michael, Alaska | |
| 3b | -35 to -30 F | Tomahawk, Wisconsin; Sidney, Montana | |
| 4a | -30 to -25 F | Minneapolis/St.Paul, Minnesota; Lewistown, Montana | |
| 4b | -25 to -20 F | Northwood, Iowa; Nebraska | |
| 5a | -20 to -15 F | Des Moines, Iowa; Illinois | |
| 5b | -15 to -10 F | Columbia, Missouri; Mansfield, Pennsylvania | |
| 6a | -10 to -5 F | St. Louis, Missouri; Lebanon, Pennsylvania | |
| 6b | -5 to 0 F | McMinnville, Tennessee; Branson, Missouri | |
| 7a | 0 to 5 F | Oklahoma City, Oklahoma; South Boston, Virginia | |
| 7b | 5 to 10 F | Little Rock, Arkansas; Griffin, Georgia | |
| 8a | 10 to 15 F | Tifton, Georgia; Dallas, Texas | |
| 8b | 15 to 20 F | Austin, Texas; Gainesville, Florida | |
| 9a | 20 to 25 F | Houston, Texas; St. Augustine, Florida | |
| 9b | 25 to 30 F | Brownsville, Texas; Fort Pierce, Florida | |
| 10a | 30 to 35 F | Naples, Florida; Victorville, California | |
| 10b | 35 to 40 F | Miami, Florida; Coral Gables, Florida | |
| 11 | above 40 F | Honolulu, Hawaii; Mazatlan, Mexico | |
Continued on page 3: Plant Examples
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