USDA Cold Hardiness
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There are many characters to consider when selecting a landscape plant, but cold hardiness is a primary consideration. Hardiness refers to the ability of a plant to survive winters in a particular area. Great genetic variation exists among species in this regard, thus plants are generally classified according to the lowest temperature they can withstand without being damaged. Similarly, geographic regions are classified according the average minimum temperature experienced by that area. The USDA has separated the United States into 11 distinct zones ("USDA Hardiness Zones"), and the New England states contain regions in zones 3 to 7. Always select plants rated hardy for your zone. Areas placed in a higher USDA Hardiness Zone experience warmer average winter temperatures, though this says nothing about summer temperatures.


This map summarizes the hardiness zones of New England. Special thanks to "People, Places and Plants" magazine for allowing use of the image. The map was prepared by Jim Lucas using information compiled by the USDA.



A Few Caveats: While the USDA cold hardiness of a plant is a good general guideline for proper selection, there are often other factors to consider. A complete discussion of this subject is beyond the scope of this database, but other variables such as soil moisture, plant age and microclimates (sites that are against a heat-retaining surface, sheltered from winter winds, in "cold pockets", etc.) can affect the performance of a plant, even if it is rated hardy for your zone. Check with local authorities if you are concerned about the survival of a particular plant in your area.