The New Almanac

USDA Zone 2a

Zone 2 · The Boreal Interior

Average annual extreme minimum temperature: -50 to -45 °F (-45.6°C to -42.8°C).

Interior Alaska's garden country — Fairbanks sits in 2b — plus the single coldest pocket of the lower 48 in north-central Minnesota. Winters average −50 to −40°F; the outdoor season runs roughly early June to late August.

By the numbers

Median last frost
May 24
Median first frost
September 4
Median season
103 days
ZIPs tracked
23

Medians across every ZIP we track in zone 2a, derived from NOAA 1991–2020 climate normals. Look up your own ZIP for local dates — within a zone, frost varies by weeks.

Where you'll find zone 2

Mostly interior Alaska: Fairbanks and the favored elevations around it and the Mat-Su Valley. In the contiguous states, only north-central Minnesota reaches 2b — the coldest zone in the lower 48.

Vegetables that earn their keep

  • Peas, the Alaskan staple (UAF)
  • Cabbage family: cabbage, broccoli, Brussels sprouts, kohlrabi
  • Root crops: carrots, beets, turnips, rutabagas, radishes
  • Kale, lettuce, mustard greens
  • Beans (short-season varieties)

Fruits & perennials that overwinter

  • Apples for zones 1–2: Rescue, Heyer #12, Patterson, Kerr, Norland (UAF)
  • Apples for zones 2–3: Parkland — "one of the leading apples grown in Alaska" — Yellow Transparent, Lodi (UAF)
  • Juneberry / saskatoon (Amelanchier alnifolia) — NDSU rates it zone 2; cultivars Regent, Honeywood, Martin, Smoky, Thiessen
  • Honeyberry / haskap — hardy zones 1–8
  • Manchurian plum and Ussurian pear — the only plum and pear types proven winter-hardy in interior/southcentral Alaska (UAF)

A zone-1 playbook with a longer bench

Everything written for zone 1 applies here — cool-season crops, indoor transplant starts (tomatoes ~8 weeks, cabbage ~6), and a wary eye on June frost — but zone 2 admits a wider roster of woody plants. Parkland apple, saskatoons, honeyberries, Manchurian plum, and Ussurian pear all carry proven northern track records.

Watch the valley floors

UAF's central warning bears repeating in zone 2's rolling terrain: cold air drains downhill, and a valley garden can freeze on a June or July night while a bench site a few hundred feet higher never does. The favored 600–1,200 ft elevations around Fairbanks earn their half-zone.

Plastic, mounds, and transplants

Clear plastic mulch (soil up to 30°F warmer on sunny days), raised beds 10–12 inches high, and indoor starts are the standard kit (UAF). With them, even warmth-lovers like tomatoes become a fighting proposition in a good summer.

Fruit trees: protect the investment

Cold-hardy crab rootstocks only; insulate young trunks against sunscald for their first three winters; fence against moose (UAF). Saskatoon and honeyberry shrubs are the lower-effort fruit here — both carry zone-2 ratings and bear early.

Plant guides, timed to your frost dates

Every guide gives its planting calendar relative to your last frost — the dates above (or your ZIP's) drop straight in.

Sources