USDA Hardiness Zone 1 Planting Guide
Zone 1 covers locations where the average annual extreme minimum winter temperature ranges from -60 to -50 degrees Fahrenheit. This page covers both subzones: zone 1a (-60 to -55 degrees F) and zone 1b (-55 to -50 degrees F).
Zone 1 Overview
Zone 1 represents the most extreme cold conditions found in North America, occurring primarily in interior Alaska. Average annual minimum temperatures plunge between negative 60 and negative 50 degrees Fahrenheit. Very few cultivated plants survive these conditions without extraordinary protection. Gardeners in zone 1 work with an extremely compressed growing season, typically less than 100 frost-free days. Despite these challenges, the extended summer daylight hours in Alaska compensate partially, driving rapid growth in cold-adapted species. Growing food is possible but requires careful variety selection, season extension structures, and an understanding that the window between last and first frost is measured in weeks rather than months.
Zone 1 Temperature Ranges
| Subzone | Min Temp (°F) | Max Temp (°F) | Description |
|---|---|---|---|
| 1a | -60°F | -55°F | Extreme arctic conditions; only the hardiest perennials survive |
| 1b | -55°F | -50°F | Interior Alaska; very limited plant selection |
Plants for Zone 1
Only the hardiest woody plants survive zone 1 winters. Native species like Alaska birch, white spruce, balsam poplar, and willows form the backbone of any landscape planting. Among ornamentals, Siberian pea shrub, some Potentilla varieties, and select native wildflowers persist through the extreme cold. Highbush cranberries and lingonberries produce edible fruit and tolerate zone 1 conditions. For ornamental ground covers, creeping juniper and native mosses work well.
Vegetable Gardening in Zone 1
Focus on the fastest-maturing varieties available. Lettuce, spinach, radishes, and other greens can be direct-sown as soon as soil is workable and will produce a harvest in 30 to 45 days. Short-season root crops like baby carrots (55 days) and turnips (40 days) are reliable. Potatoes handle cool soil and produce in 60 to 90 days depending on variety. Bush peas and bush beans in their quickest-maturing forms (45 to 50 days) can succeed. Tomatoes and peppers require starting indoors months ahead and transplanting into protected structures.
Frost Protection & Season Tips for Zone 1
Season extension is not optional in zone 1 — it is the only way to grow most food crops. Heated or unheated high tunnel greenhouses can extend the growing period by four to eight weeks on each end. Cold frames, hot beds with decomposing manure, and wall-of-water protectors help individual plants survive cold snaps during the brief summer. Raised beds with dark-colored sides and covers absorb maximum solar energy. Planting on south-facing slopes takes advantage of solar heating and cold air drainage.