Anchorage, AK Frost Dates
Average frost dates, USDA hardiness zone, and growing season length for Anchorage, Alaska.
Gardening in Anchorage
Alaska's largest city proves that gardening thrives even at 61° north latitude. The summer growing season is brief but explosive — 19+ hours of daylight in June produce growth rates that Lower 48 gardeners find hard to believe.
Zone 4b with a growing season of only 123 days — but those days are long. Really long. The midnight sun effect means plants photosynthesize nearly around the clock in June and July, producing cabbages, zucchini, and pumpkins of record-breaking size. The maritime influence from Cook Inlet moderates temperatures, making Anchorage milder than interior Alaska.
The Alaska State Fair's giant vegetable competition is legendary — 100+ pound cabbages, 2,000+ pound pumpkins. It's not a gimmick; it's the natural result of 19-hour days on fertile glacial soil. Anchorage's community garden scene is surprisingly robust for a city most people associate with wilderness, not vegetable patches.
What This Means for Anchorage Gardeners
The average last spring frost in Anchorage is around May 15, and the average first fall frost arrives around September 15. That gives you approximately 123 frost-free days to work with.
123 frost-free days means every warm day counts. Focus on cold-hardy crops that thrive in your moderate temperatures: kale, lettuce, peas, radishes, potatoes, and root vegetables. For warm-season crops, choose only the shortest-season varieties (sub-65-day tomatoes, 55-day beans) and start everything indoors. Season extension — row covers, cold frames, plastic mulch — isn't a luxury here, it's essential infrastructure.
These dates are based on NOAA 30-year Climate Normal data for the Anchorage area. Your actual frost dates could shift 2-3 weeks in either direction in any given year. Learn more about our data sources.
What to Grow in Anchorage
With 123 frost-free days, Anchorage gardeners need to plan strategically — start warm-season crops indoors and choose short-season varieties. Cool-season crops are your strength, thriving in the moderate temperatures that define your growing window. Recommended starting points: kale, lettuce, peas, carrots, potatoes, radishes, garlic, and short-season tomatoes.
See the full Alaska planting guide for all 40 plants: Alaska Planting Calendar. Or enter your zip code for exact planting dates personalized to Anchorage.
More About Zone 4B
Anchorage is in USDA Hardiness Zone 4B, which means average annual extreme minimum temperatures between -25°F to -20°F. View the full Zone 4B planting guide.
See the complete planting calendar for Alaska: Alaska Planting Calendar.
Other Cities in Alaska
Frequently Asked Questions
These dates are based on NOAA's 30-year Climate Normal data for the Anchorage area. They represent historical averages, not predictions. In any given year, the actual last frost could be 2-3 weeks earlier or later. Microclimates within Anchorage (urban heat islands, hilltops, low-lying valleys) can also shift your local frost dates by a week or more.
Start everything possible indoors — your 123-day season doesn't leave room for a slow start. Direct sow only the fastest, hardiest crops (radishes, lettuce, peas) 3-4 weeks before last frost (May 15). Choose short-season varieties for warm crops. Enter your zip code for exact dates.