USDA hardiness zone 2b
In zone 2b, the average annual extreme minimum temperature is -45 to -40°F (-42.8 to -40.0°C), based on 1991–2020 data from the 2023 USDA Plant Hardiness Zone Map.
What zone 2b means for your garden
A plant labeled "hardy to zone 2b" should survive a typical winter low of -45°F. Only very cold-hardy perennials survive; look for plants rated to this zone or colder, and use season-extension for vegetables. Zone 2a is the colder half of zone 2.
ZIP codes in zone 2b: 17 in Alaska. New to zones? Read how to read your hardiness zone.
Frost dates in zone 2b
No major city on this site is in zone 2b. Typical 30%-risk frost dates (estimate from 6 NOAA stations): last spring frost around May 20, first fall frost around Sep 3. Treat these as rough estimates — local frost dates vary a lot with elevation.
Estimated planting calendar for zone 2b
Based on the estimated frost dates above.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Mar 25 – Apr 8 | May 27 – Jun 10 | — | — |
| Pepper Short season (106 frost-free days): choose early varieties. | Mar 11 – Mar 25 | Jun 3 – Jun 17 | — | — |
| Lettuce | Apr 8 – Apr 22 | May 6 – May 27 | Apr 22 – Jun 3 | Jun 25 – Jul 23 |
| Green Beans | — | — | May 27 – Jul 1 | — |
| Sweet Corn Short season (106 frost-free days): choose early varieties. | — | — | May 27 – Jun 24 | — |
| Zucchini & Summer Squash | Apr 22 – Apr 29 | May 27 – Jun 10 | May 27 – Jun 17 | — |
| Cucumber | Apr 22 – Apr 29 | Jun 3 – Jun 10 | May 27 – Jun 17 | — |
| Carrot | — | — | Apr 29 – Jun 3 | — |
| Onion | Feb 25 – Mar 11 | Apr 22 – May 6 | — | — |
| Potato | — | Apr 22 – May 13 | — | — |
| Basil Short season (106 frost-free days): choose early varieties. | Apr 8 – Apr 22 | Jun 3 – Jun 17 | Jun 3 – Jun 24 | — |
| Spinach | — | — | Apr 8 – May 6 | Jul 9 – Aug 6 |
| Kale | Mar 25 – Apr 8 | Apr 22 – May 13 | Apr 22 – May 13 | Jun 25 – Jul 23 |
| Broccoli | Mar 25 – Apr 8 | May 6 – May 27 | — | — |
| Peas | — | — | Apr 8 – Apr 29 | Jun 25 – Jul 9 |
| Eggplant Short season (106 frost-free days): choose early varieties. | Mar 11 – Mar 25 | Jun 3 – Jun 17 | — | — |
| Cabbage | Mar 25 – Apr 8 | Apr 22 – May 6 | — | — |
| Radish | — | — | Apr 15 – Jun 3 | Jul 23 – Aug 20 |
| Strawberry | — | Apr 22 – May 13 | — | — |
| Beets | — | — | Apr 29 – Jun 10 | Jun 25 – Jul 9 |
Where zone 2b occurs
None of the 512 major cities on this site sits in zone 2b. It occurs mostly in thinly populated areas (ZIP codes: 17 in Alaska).
← Zone 2a · Zone 3a → · All zones
Zone 2b questions
How cold does it get in zone 2b?
Zone 2b is defined by an average annual extreme minimum temperature of -45 to -40°F (-42.8 to -40.0°C) for 1991–2020 — the average of each year's single coldest night, not the record low. Individual winters can be colder, so plants rated exactly for zone 2b carry some risk in a severe year.
When is the last frost in zone 2b?
Roughly May 20 for spring and Sep 3 for the first fall frost (estimate from 6 NOAA stations). Treat these as rough: frost dates swing widely with elevation.
Which states have zone 2b?
The 2023 listings put 17 ZIP codes in zone 2b, spread over 1 states and territories. The most are in Alaska (17).
Did zone 2b grow on the 2023 map?
Yes: 15 ZIP codes were in zone 2b on the 2012 map and 17 are on the 2023 map (+2). Of today's zone 2b ZIP codes that were also listed in 2012, 59% were in a colder zone then, 35% were already 2b, and 6% were in a warmer zone. What changed in 2023.