The United States Department of Agriculture has provided gardeners across America this nifty little tool called the 'Hardiness Zone Map.'

The USDA Plant Hardiness Map is a good tool to use when deciding what plants will grow well in your region. If you don't already know your Zone, check out the links below for the Zone Map to your part of the country. As this is a U.S. government agency, they didn't think to include other countries, but our Canadian visitors can simply use the temperature guides below (or on the maps) to find out your USDA Zone equivalent for your area. You may have to consult with your local weather records to be sure.

Hardiness zones are sometimes referred to in gardening books, magazines as well as in mail order catalogs and nurseries. The GreenWeb sometimes references this information and is in the process of updating it's seed listings with the information whenever available.

It's important to remember that Zone information is a guideline. Within any region there are different climates due to various factors, like topography, water masses, canyon and mountain landmarks. These can cause airflows to be altered locally which can be enough to raise or lower your lowest temperature, thus possibly changing the appropriate Zone for your garden.

For plants that will grow inside your home, Hardiness Zones become far less important. Unless your prone to forgetting to pay the heating bill, it's doubtful the temperature will ever drop below Zone 11 (40 degrees Fahrenheit / 4.4 degrees Celsius). So, for all intensive purposes, you can consider your houseplant environment like Hawaii ! Many tub and container plants can take advantage of your home by being moved inside when the weather chills, and then back outside after the last frost has hit. Sort of a tropical winter-long vacation for your plants. Since plants also add to the home environment as well as freshening, cleaning and oxygenating the air, it's also a pleasant way for you to spend the winter as well. Especially considering that winter weather may force you to spend more time indoors.

Here are the links that will take you to the right Zone Map for your region. Be patient as they may take a few moments to load. For additional and detailed information about your Zone, look on this page past the map links that follow.

USDA ZONE MAP for Alaska & Hawaii, USA

USDA ZONE MAP for the Eastern Half of the USA Mainland

USDA ZONE MAP for the Western Half of the USA Mainland

Additional and Detailed USDA Hardiness Zone Info!

Below are specific details about what comprises your USDA Plant Hardiness Zone (or foreign equivalent) including the Celsius temperatures too. You'll also find some official USDA definitions and projected frost dates as well.

Approximate range of Average
    Annual MINIMUM Temperatures

  C = Centigrade/ F = Fahrenheit

  Zone 1 = below -45C/ -50F
  Zone 2 = -45C/-40C -50F/-40F
  Zone 3 = -40C/-34C -40F/-30F
  Zone 4 = -34C/-29C -30F/-20F
  Zone 5 = -29C/-23C -20F/-10F
  Zone 6 = -23C/-18C -10F/ 0F
  Zone 7 = -18C/-12C 0 F/+10F
  Zone 8 = -12C/- 7C +10F/+20F
  Zone 9 = - 7C/- 1C +20F/+30F
  Zone 10 = - 1C/+ 4C +30F/+40F
  Zone 11 = above+4C/ +40F
                

Average Zone Frost Dates

 NOTE: The dates below are for the Northern Hemisphere

                

Zone 1 = Average dates Last Frost = 1 Jun / 30 Jun
Average dates First Frost = 1 Jul / 31 Jul
Note: vulnerable to frost 365 days per year

Zone 2 = Average dates Last Frost = 1 May / 31 May
Average dates First Frost = 1 Aug / 31 Aug


Zone 3 = Average dates Last Frost = 1 May / 31 May
         Average dates First Frost = 1 Sep / 30 Sep

Zone 4 = Average dates Last Frost = 1 May / 30 May
         Average dates First Frost = 1 Sep / 30 Sep

Zone 5 = Average dates Last Frost = 30 Mar / 30 Apr
         Average dates First Frost = 30 Sep / 30 Oct


Zone 6 = Average dates Last Frost = 30 Mar / 30 Apr
  Average dates First Frost = 30 Sep / 30 Oct

Zone 7 = Average dates Last Frost = 30 Mar / 30 Apr
  Average dates First Frost = 30 Sep / 30 Oct
 
Zone 8 = Average dates Last Frost = 28 Feb / 30 Mar
  Average dates First Frost = 30 Oct / 30 Nov

Zone 9 = Average dates Last Frost = 30 Jan / 28 Feb
Average dates First Frost = 30 Nov / 30 Dec

Zone 10 = Average dates Last Frost = 30 Jan or before
Average dates First Frost = 30 Nov / 30 Dec

Zone 11 = Free of Frost throughout the year.

Frost Definitions:
                

Frost:  Light Freeze. damage depends upon
  length of frost duration.
                

Light Freeze:  -2C/-0C OR 29F/32F - tender plants
  killed with little destructive
  effect on other vegetation.
                

Moderate Freeze: -8C/-2C OR 25F/28F - wide destruction
  on most vegetation with heavy
  damage to fruit blossoms and
  tender semi-hardy plants.
                

Severe Freeze:  -9C OR 24F and colder, heavy damage
  to most plants.
                

Sunlight Definitions:
                

Shade:  Usually an area under a closed tree canopy
  that receives no direct sun at all.
                

Partial  Usually an area under a lone or limited
Shade:  number of trees receiving only a 1 to 5
  hours of dappled sun during the day.
                

Partial  Usually refers to an area that receives
  Sun:  approximately 3 - 5 hours of full
  sun per day.
                

Full Sun: Refers to an area receiving 6 or more
  hours of full sun per day.
                

Hopefully by now, you're not all zoned out. If you have further questions about your zone, you might find additional information from the USDA's own plant database web site which can be found in our "Other Plant Loving Links" section under databases.