Canadian zones are numbered 0–9 and run roughly one number lower than USDA at the cold end. The official system also weighs frost-free days, summer rainfall, summer maximum, snow cover and wind, so map values to your area using the official map for accuracy.
The Canadian bands
| Band | Temperature range | Description |
|---|---|---|
| Zone 0 | down to −45 °C | Northern sub-arctic |
| Zone 1 | −45 °C to −40 °C | Far north, severe winters |
| Zone 2 | −40 °C to −34 °C | Prairie cold |
| Zone 3 | −34 °C to −29 °C | Very cold winters |
| Zone 4 | −29 °C to −23 °C | Cold winters |
| Zone 5 | −23 °C to −18 °C | Moderately cold winters |
| Zone 6 | −18 °C to −12 °C | Milder cold |
| Zone 7 | −12 °C to −7 °C | Mild winters with light freezes |
| Zone 8 | −7 °C to −1 °C | Coastal mild — light frost |
| Zone 9 | −1 °C and warmer | Mildest pockets, near frost-free |
How Canadian compares to the other systems
Hardiness scales do not translate one-to-one, because each was built for a different climate and reads in a different direction. Compare the Canadian scale with the other three:
- USDA hardiness zone (United States) – plant tolerates down to this zone.
- RHS hardiness rating (United Kingdom) – plant needs at least this level of cold tolerance.
- Australian (ANBG) zone (Australia) – plant tolerates down to this zone.
Example plants rated in the Canadian system
- Bog myrtle (Sweet gale) Myrica gale – Zone 1–6
- Apothecary’s rose Rosa gallica ‘Officinalis’ – Zone 3–8
- Hairy vetch Vicia villosa – Zone 3–9
- Spike speedwell Veronica spicata – Zone 3–8
- Foxglove Digitalis purpurea – Zone 4–8
- Shagbark hickory Carya ovata – Zone 4–7
- Fountain grass Pennisetum alopecuroides – Zone 5–8
- Apple — Monty's Surprise Malus domestica "Monty's Surprise" – Zone 6–9
- Montbretia Crocosmia × crocosmiiflora – Zone 7–9
- Loquat Eriobotrya japonica – Zone 8–9
- Bibhitaki Terminalia bellirica – Zone 9
- Gymea lily Doryanthes excelsa – Zone 9
- Passionfruit — Yellow Passiflora edulis f. flavicarpa – Zone 9
- Yesterday-today-and-tomorrow Brunfelsia pauciflora – Zone 9