USDA hardiness zones in Alaska
| Zone | Avg. extreme minimum | ZIP codes | Example cities |
|---|---|---|---|
| Zone 1a | −60 to −55°F | 5 | — |
| Zone 1b | −55 to −50°F | 11 | — |
| Zone 2a | −50 to −45°F | 23 | Fairbanks |
| Zone 2b | −45 to −40°F | 16 | — |
| Zone 3a | −40 to −35°F | 18 | — |
| Zone 3b | −35 to −30°F | 26 | — |
| Zone 4a | −30 to −25°F | 30 | Bethel |
| Zone 4b | −25 to −20°F | 28 | Kenai |
| Zone 5a | −20 to −15°F | 23 | Anchorage, Wasilla, Palmer |
| Zone 5b | −15 to −10°F | 12 | — |
| Zone 6a | −10 to −5°F | 4 | Juneau, Homer |
| Zone 6b | −5 to 0°F | 8 | — |
| Zone 7a | 0 to 5°F | 16 | — |
| Zone 7b | 5 to 10°F | 13 | Sitka, Kodiak |
| Zone 8a | 10 to 15°F | 8 | Ketchikan |
| Zone 8b | 15 to 20°F | 4 | — |
Growing zone and frost dates by city
| City | Zone | Frost dates |
|---|---|---|
| Anchorage | 5a (−20 to −15°F) | Anchorage frost dates |
| Juneau | 6a (−10 to −5°F) | Juneau frost dates |
| Fairbanks | 2a (−50 to −45°F) | Fairbanks frost dates |
| Wasilla | 5a (−20 to −15°F) | Wasilla frost dates |
| Sitka | 7b (5 to 10°F) | Sitka frost dates |
| Ketchikan | 8a (10 to 15°F) | Ketchikan frost dates |
| Kenai | 4b (−25 to −20°F) | Kenai frost dates |
| Palmer | 5a (−20 to −15°F) | Palmer frost dates |
| Bethel | 4a (−30 to −25°F) | Bethel frost dates |
| Homer | 6a (−10 to −5°F) | Homer frost dates |
| Kodiak | 7b (5 to 10°F) | Kodiak frost dates |
Frequently asked questions
What growing zone is Alaska in?
Alaska’s ZIP codes span USDA zones 1a to 8b, and 4a is the most common. Zones vary with elevation and distance from water, so check your own ZIP code.
When should I plant?
Hardiness zones are about winter cold, not planting dates. For timing, use the last spring frost date for your city on our Alaska frost dates page.