The United States Department of Agriculture (USDA) has developed a map depicting the average annual minimum temperature in belts across Canada, in the United States. States (Hawaii) and Mexico. Zones 1 through 7a cover Canada, where the lowest zone numbers are the extreme north or highest elevations.
The table can be used to help determine which plants, including trees, flowers and shrubs, can survive the winter. temperature Trees, flowers and shrubs have been rated by the nursery to indicate which USDA street hardiness zones are best suited. At the end of the article are listed some plants that can survive long, cold winters in Canada.
Arctic Circle and Yukon Territory
All north of the Arctic Circle and most of the Yukon Territory are in USDA zone 1. In zone 1, the average annual minimum temperature is below -50 degrees F or -45.6 degrees C.
Northern Territory and Nunavut
The Northern Territory and Nunavut fall into USDA zone 2a, where the average annual minimum temperature is between -50 to -45 degrees F or -42.9 to -45.5 degrees C.
British Columbia
The northern part of British Columbia is in zones 2a (-50 to -45 degrees F or -42.8 to -45.5 degrees C) and 2b (-45 to -40 degrees F or -40.0 to -42.7 degrees C). Mountain areas are in zones 3a (-40 to -35 degrees F or -37.3 to -39.9 degrees C) or 3b (-35 to -30 degrees F or -34.5 to -37.2 degrees C).
Along the coast is zone 7a (0 to 5 degrees F or 12.3 to 14.9 degrees C). Moving inland from the coast, the zones progress rapidly upward from 6b (-5 to 0 degrees F or -17.8 to -20.5 degrees C) to 4a (-30 to -25 degrees F or -31.7 to -34.4 degrees C).
Alberta, Saskatchewan, Manitoba, Ontario and Quebec
Mountain areas are in zones 3a (-40 to -35 degrees F or -37.3 to -39.9 degrees C) or 3b (-35 to -30 degrees F or -34.5 to -37.2 degrees C). Most of the area is in zones 2a (-50 to -45 degrees F or -42.8 to -45.5 degrees C) and 2b (-45 to -40 degrees F or -40.0 to -42.7 degrees C). Depending on the borders of the United States, the provinces are in zones 3a (-40 to -35 degrees F or -37.3 to -39.9 degrees C) or 3b (-35 to -30 degrees F or -34.5 to -37.2 degrees C).
New land
The western part of Newfoundland is in zones 3a (-40 to -35 degrees F or -37.3 to -39.9 degrees C) or 3b (-35 to -30 degrees F or -34.5 to -37.2 degrees C). The eastern part of Newfoundland is in zones 4a (-30 to -25 degrees F or -31.7 to -34.4 degrees C), and to the sea 4b (-25 to -20 degrees F or -28.9 to -31.6 degrees C). .
Nova Scotia
Northern Nova Scotia is in zone 4a (-30 to -25 degrees F or -31.7 to -34.4 degrees C). Southern Nova Scotia is in zone 4b (-25 to -20 degrees F or -28.9 to -31.6 degrees C).
Prince Edward Island and Labrador
Northern areas are in zone 5a (-20 to -15 degrees F or -26.2 to -28.8 degrees C). Southern areas are in zone 6a (-10 to -5 degrees F or -20.6 to -23.3 degrees C).
Plant Options for Each USDA Zone in Canada
The following are a few plants that can survive the winter in USDA plants in Canada.
PLAGA 1. Although no perennial flowers can tolerate zone 1 winter temperatures, shrubs such as Dwarf Birch, Lapland Rhododendron or Black Crowberry survive through the end of the cold winter.
PLAGA 2. Bunchberry (small bush); American four-legged bush (a large shrub); Paper Birch (tall tree)
ZONE 3a-b. Sugar Maple and Siberian Crabapple (trees); Van Houtte Spirea (artex); Astilbe and Daylilies (perennial)
ZONE 4a-b because of 5a-b. Maple and Flowering Dogwood (trees); Chinese Juniper and Japanese yew (frame); Dianthus and Iris
ZONE 6a-b, through ZONE 7a-b. American Holly and Big Leaf Maple (trees); Azalea and Rhododendron (trees); Hosta and Peony (perennial)
Sources:
U.S.ForestService: PlantHardinessZones
U.S. National Arboretum: ZoneDetail
PlantsByUSDAzones
