USDA hardiness zone
Zone 1b
Rolled up from the 11 ZIP codes in our data that are classified zone 1b, covering 0 nurseries and garden centers across 0 cities we track in this zone.
Average minimum winter temperature
-55°F
Last spring frost range
May 18–Jun 3
First fall frost range
Aug 23–Sep 8
Average frost-free growing season
93 days
Average monthly temperature
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| -9.9° | -1.5° | 6.7° | 27.9° | 46.1° | 57.9° | 59.9° | 53.6° | 42.5° | 24° | 2.8° | -5.8° |
NOAA 1991–2020 Climate Normals, averaged across this zone's member ZIPs.
Crops by frost hardiness
What grows here, and when
This zone's own last-frost dates range across May 18–Jun 3. Hardy and semi-hardy crops can go in before that date; tender and very-tender crops need to wait until after it. See each crop's own guide for exact windows at a specific location in this zone.
Planting windows and crop timing here are computed from USDA/NOAA climate data and the university extension sources cited below, not a site visit or soil test. Treat this as a starting point: local conditions vary, and a local nursery or extension office can advise on your exact site. See our full Disclaimer.
Hardy (49)
- Apple (bare-root fruit tree)
- Apricot (bare-root fruit tree)
- Asparagus
- Bachelor's Button (Cornflower)
- Bare-root rose
- Blackberry
- Blueberry
- Broccoli
- Brussels Sprouts
- Cabbage
- Calendula
- Catnip/Catmint
- Cherry (sweet/tart, bare-root fruit tree)
- Chives
- Collards
- Currant
- Deciduous shade tree (generic, e.g. maple/oak, bare-root or B&B)
- Elderberry
- Evergreen shrub (B&B/potted, e.g. arborvitae, boxwood)
- Flowering deciduous shrub (generic, e.g. lilac/forsythia)
- Garden Peas
- Garlic
- Gooseberry
- Kale
- Kohlrabi
- Larkspur
- Lavender
- Lettuce
- Mint
- Onion (bulb)
- Oregano
- Peach (bare-root fruit tree)
- Pear (bare-root fruit tree)
- Plum (bare-root fruit tree)
- Radish
- Raspberry
- Rhubarb
- Rutabaga
- Sage
- Snapdragon
- Snow Peas
- Spinach
- Strawberry
- Sweet Alyssum
- Sweet Pea
- Table/Bunch Grape
- Tarragon
- Thyme
- Turnip
Semi-hardy (16)
Tender (20)
Zone 1b means an average annual extreme minimum winter temperature of -55°F to -50°F on the 2023 USDA Plant Hardiness Zone Map, built by USDA/ARS with the PRISM Climate Group at Oregon State University from 1991-2020 records. USDA publishes no official ZIP-code lookup for that map; every ZIP behind this rollup carries its zone matched by centroid against the map, not by its polygon boundary, through phzmapi.org's ZIP-level derivation.
The frost and season figures above are real spreads across this zone's own ZIPs, not rounding noise. At a winter this cold, the number that matters most for a gardener is the growing-season length shown above, not the exact frost date either side of it: a season this short leaves room for one crop cycle a year, not two, and only for crops whose maturity window fits inside it. Zone 1b tells you about winter cold alone; it says nothing about summer heat, rainfall, or day length.
We hold zero nurseries with a ZIP in zone 1b. Every ZIP in this band sits in Alaska.
Nearby zones
All zones
USDA 2023 Plant Hardiness Zone Map (zone boundaries, via the phzmapi.org ZIP-level derivation) and NOAA 1991–2020 Climate Normals (frost dates, growing season, monthly temperatures).