Hardiness zones provide information by which gardeners and growers can determine which perennial plants are most likely to grow at a location. Canada and the US each use different, not interchangeable plant hardiness zones labelled with numbers and letters. Zones in Canada provided by National Resources Canada are determined by a variety of climatic conditions, including rainfall, frost-free periods, maximum snow depth, and more.
Canada’s plant hardiness zones range from 0, where weather is extremely harsh, to zone 8 which comprises certain areas along the west coast of British Columbia. American zones published by the United States Department of Agriculture (USDA) are based on the average lowest temperatures experienced in a region each year. Using USDA Zones in Canada – While both systems differ from another, one can still rely upon using the USDA zones for Canada. A simple temperature conversion from Fahrenheit (F) to Celsius (C) is the answer.
Urban Sprawl & Micro-climates
Regardless of sophisticated calculations, hardiness zone conditions are unstable as the climate is changing. Additional factors created by micro-climates such as terrain features, bodies of water, wind, fire or smoke or even buildings and human activities make it difficult to determine whether plants can survive in certain areas or not.
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