The “Plant Hardiness Zone Map” was originally developed in 1960 and has had several updates throughout the years. It outlines the coldest temperatures on average for different areas throughout Canada. This information helps you choose plant materials that are most likely to survive the winters in your area.
Here in Medicine Hat area we are lucky to be in one of the warmest climates in Alberta during the winter months at a Warm Sunny Zone 4B! This means we have a lot more plants to choose from that can typically grow in our area. Any Tree, Shrub, Perennial and some Annuals in the zone 4B to zone 1 should survive our winters with proper care. It is possible to enjoy plant materials in the zone 5 category by creating our own little micro-climate. Examples of this would be to plant in a protected area close to your house and creating a protective insulating barrier to keep temperatures even around your plant and protect from drying cold winds.
Please note this zone map and information is a guide only and does not guarantee survival of your plant material as climatic conditions are constantly changing and there are many other factors that can affect the success and failure of your plants. This information reflects the most recent data collected and presented by Natural Resources Canada. See www.planthardiness.gc.ca for more information.
Canada’s Plant Hardiness Zones
Alberta Frost Dates
Frost dates are arranged by region and include the first frost date of the season and the final frost date of the season. For the Medicine Hat area this means on a normal year, we can put our plants outside safely after May 20 and we will normally have our first killing frost around September 30. These are the average frost dates for Alberta and may not be reliable in a particular year as there are many variables such as micro-climates that can cause fluctuations.
| LOCATION | LAST FROST | FIRST FROST |
| Athabasca, AB | May 21 – 31 | September 1-10 |
| Calgary, AB | May 11 – 20 | September 11 – 20 |
| Edmonton, AB | May 1 – 10 | September 11 – 20 |
| Grande Prairie, AB | May 11 – 20 | September 1 – 10 |
| Lethbridge, AB | May 21 – 31 | September 1 – 10 |
| Medicine Hat, AB | May 11 – 20 | September 21 – 30 |
| Red Deer, AB | May 11 – 20 | September 11 – 20 |
| Burstall, SK | May 21 – 31 | September 1 – 10 |
| Leader, SK | May 11 – 20 | September 11 – 20 |
| Maple Creek, SK | May 11 – 20 | August 21 – 31 |
| Swift Current,SK | May 21 – 31 | September 11 – 20 |