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USDA hardiness zone is used in United States; Canadian plant hardiness zone is used in Canada. Both are anchored to temperature, so they can be lined up — but they divide the scale differently, and one band in one system often spans two in the other. Treat the table below as the nearest equivalent, not a precise translation.
They are not the same kind of claim. Plant tolerates down to this zone. Plant tolerates down to this zone. That difference matters more than the numbers: reading one as though it were the other is the single most common way a plant ends up bought for the wrong garden.
USDA to Canadian conversion table
| USDA | Temperature range | Canadian equivalent | What it means |
|---|---|---|---|
| Zone 1 | down to −45.6 °C | Zone 0 | Sub-arctic — winter lows below −45 °C |
| Zone 2 | −45.6 °C to −40 °C | Zone 0, Zone 1 | Severe continental cold |
| Zone 3 | −40 °C to −34.4 °C | Zone 2 | Very cold winters |
| Zone 4 | −34.4 °C to −28.9 °C | Zone 2, Zone 3, Zone 4 | Cold winters, short growing season |
| Zone 5 | −28.9 °C to −23.3 °C | Zone 4 | Cold continental winters |
| Zone 6 | −23.3 °C to −17.8 °C | Zone 4, Zone 5, Zone 6 | Moderately cold winters |
| Zone 7 | −17.8 °C to −12.2 °C | Zone 6 | Mild cold winters |
| Zone 8 | −12.2 °C to −6.7 °C | Zone 6, Zone 7, Zone 8 | Mild winters with light freezes |
| Zone 9 | −6.7 °C to −1.1 °C | Zone 8 | Light frost only |
| Zone 10 | −1.1 °C to 4.4 °C | Zone 8, Zone 9 | Near frost-free |
| Zone 11 | 4.4 °C to 10 °C | Zone 9 | Frost-free, warm winters |
| Zone 12 | 10 °C to 15.6 °C | Zone 9 | Tropical |
| Zone 13 | 15.6 °C and warmer | Zone 9 | Hot tropical |
Why the conversion is approximate
A plant rated USDA zone X survives in zone X and warmer. Your zone number should be at or above the plant's rating to grow it outdoors.
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.
Because the two systems were built for different places and different questions, a converted number tells you roughly where a plant sits on the cold scale — not whether it will thrive. Summer heat, humidity, rainfall pattern and the length of your growing season all matter, and none of them appears in either rating.
Check a rating against your own conditions
Converting the number is only half the job. Cross-check a rating against your own climate, or find your zones in all four systems by answering a short set of questions about where you garden.
See also the full band tables for USDA hardiness zone and Canadian plant hardiness zone.