Canada updates plant hardiness zones after decade
For the first time in more than a decade, Canada’s plant hardiness zone map has been updated, offering growers across the country a more accurate tool to guide planting decisions. Developed by scientists, John Pedlar and Dan McKenney, at Natural Resources Canada (NRCan), the map uses advanced climate science and plant modelling to reflect changing conditions.
The hardiness zone map, in use since the 1960s, rates regions from Zone 0 (coldest) to Zone 9 (warmest) based on temperature, precipitation, frost-free periods, and other factors.
Recent updates reveal a warming shift, with many areas moving up by half a zone or more. In some cases, shifts are as large as two full zones — such as Yellowknife, Northwest Territories, which moved from Zone 0b to 1b. This change opens possibilities for growing new species, such as Saskatoon berry and red osier dogwood, but also brings risks from extreme weather events.
These changes are already influencing agriculture. In Ontario, for example, viticulture is expanding north of traditional wine regions. However, unpredictable frosts, droughts, and heatwaves still threaten crops.
The updated online map offers more than just general zone information. Users can view maps for thousands of specific plant species, showing where conditions are suitable now and where they may be in the future. This is made possible through species distribution modelling, which draws on professional and citizen science data.
Researchers are also working on a “heat zone” map to track areas prone to excessive heat events and exploring specialized models for crops like apples.
For gardeners, farmers, and foresters, this new resource provides valuable insight into what plants will thrive in changing climates — and what challenges to expect.
Click here to see the map: https://natural-resources.canada.ca/stories/simply-science/zone-canada-s-plant-hardiness-zone-maps-website-get-update
Photo Credit: Natural Resources Canada