This 4th edition Plant Hardiness Zones map shows updated zones related to perennial plant survival in Canada. The map is based on a formula using seven climate variables that influence plant survival:

1. Monthly mean of the daily minimum temperatures of the coldest month.

2. Mean frost-free period above 0°C in days.

3. Amount of rainfall from June to November.

4. Monthly mean of the daily maximum temperatures of the warmest month.

5. A winter harshness index related to rainfall in January.

6. Mean maximum snow depth.

7. Maximum wind gust in 30 year period.

The original map was developed by Agriculture and Agri-Food Canada in the early 1960s based on average climate values from 1930 to 1960. This new map uses 1991 to 2020 averages. The map shown to the left of this map shows an alternative plant hardiness zone approach using just one climate variable: average extreme minimum temperature for the period 1991 to 2020. This was originally developed by scientists at the United States Department of Agriculture (see https://www.usna.usda.gov/science/plant-hardiness-zone-map/ ).

The development of these maps was made possible through a collaborative effort by scientists at Natural Resources Canada’s Canadian Forest Service, Environment Canada, and Agriculture and Agri-Food Canada. A paper describing the research, “Updated plant hardiness zones for Canada and assessment of change over time”, can be found in Scientific Reports, Vol. 15(1), 22774 ( https://doi.org/10.1038/s41598-025-00931-5 ).These maps were produced by the Canada Centre for Mapping and Earth Observation, Natural Resources Canada.

To view an interactive version of this map and for more information on plant hardiness zones in Canada,

please go to: https://www.planthardiness.gc.ca.