Alberta Hardiness Zones — by City & Region
Alberta is a cold, continental Prairie province — mostly Zone 3b to 4b, warmest in the chinook-belt southeast. Find your city's plant zone, frost dates, and growing season.
Updated July 2026 · Natural Resources Canada Plant Hardiness Zone Map + Environment and Climate Change Canada normals (1991–2020)
Alberta hardiness zones: the province is almost entirely Zone 3 to 4. The warmest is Zone 4b in the chinook-belt southeast (Medicine Hat, Brooks); Calgary, Edmonton, and Lethbridge are Zone 4a, Red Deer is Zone 3b, and the far north drops to Zone 1–2. Two Alberta quirks: chinook winds spike winter temperatures in the south (hard freeze-thaw on perennials), and high elevation keeps last frosts late (Calgary ~May 25). Zones come from Natural Resources Canada and are not identical to U.S. (USDA/Montana) zones. Find your exact zone at planthardiness.gc.ca or with our interactive Zone Finder.
🌾 Alberta Zones at a Glance
Alberta Hardiness Zone by City
Cities below are drawn from our frost-date dataset (Environment and Climate Change Canada normals + Natural Resources Canada zones), sorted from the warmest zone to the coldest. Tap a city with a link for its full month-by-month planting guide.
| City | Zone | Last Frost | First Frost | Season |
|---|---|---|---|---|
| Medicine Hat | 4b | May 15 | Sep 22 | 130 days |
| Calgary › | 4a | May 25 | Sep 15 | 113 days |
| Edmonton › | 4a | May 15 | Sep 20 | 128 days |
| Lethbridge › | 4a | May 18 | Sep 20 | 125 days |
| Red Deer › | 3b | May 22 | Sep 15 | 116 days |
Frost dates are historical averages; actual dates vary year to year, and in Alberta frost can strike in any month at elevation — add 1–2 weeks of buffer before transplanting frost-sensitive crops. Zones shift with elevation and cold-air drainage (see below).
Alberta's Zones, Warmest to Coldest
Chinooks & Elevation: Alberta's Zone Wildcards
Two things make an Alberta zone number tell only half the story. Chinooks — warm winter winds off the Rockies — can lift southern Alberta from −20°C to +10°C in hours. That sounds gardener-friendly, but the repeated freeze-thaw breaks winter dormancy, then re-freezes tissue, causing winterkill and desiccation that a steady cold winter wouldn't. Reliable snow cover and mulch protect perennials far better than a mild-sounding chinook zone implies. Elevation is the other wildcard: Calgary's altitude gives it one of the latest last-frost dates of any major Canadian city (around May 25) and frost risk in any month — so pick perennials a zone hardier than your rating suggests, and don't rush tender vegetables outdoors.
Why Alberta Zones Aren't the Same as U.S. Zones
If you buy plants or read advice from across the Montana border, don't take a USDA zone at face value. The U.S. system is based on winter minimum temperature alone. Natural Resources Canada's system factors in seven variables — winter minimum, summer maximum, frost-free period, rainfall, snow cover, and wind — so a Canadian "Zone 4" is defined differently from a USDA "Zone 4," even though the number is the same. NRCan publishes a separate USDA-method map for cross-border comparison if you need it.
Practical rule for Alberta: use the Canadian (NRCan) zone from planthardiness.gc.ca for Canadian-sourced plants, and treat a U.S. plant tag's zone as a rough guide only. When in doubt, pick the hardier (lower-numbered) option — Alberta's chinook freeze-thaw punishes borderline choices.
Source & how to cite: Zone assignments follow the Natural Resources Canada Plant Hardiness Zone Map (planthardiness.gc.ca); frost dates are Environment and Climate Change Canada climate normals (1991–2020). Enter your address on the NRCan map for a location-specific zone that accounts for Alberta's elevation and frost pockets.
Alberta City Planting Guides
Your zone tells you what survives the winter; these guides tell you exactly what to sow and transplant, week by week, for your city.
Zone 4a · last frost May 25 Edmonton Planting Guide ›
Zone 4a · last frost May 15 Lethbridge Planting Guide ›
Zone 4a · last frost May 18 Red Deer Planting Guide ›
Zone 3b · last frost May 22
Find your exact zone & what to plant now
Click your province on the interactive map, or jump straight to your city's frost-based planting timeline.