What does USDA hardiness zone 2b mean in Alaska?

Zone 2b means an average annual extreme minimum winter temperature of −45 to −40 °F — the standard USDA measure of which perennials survive winter. 11 locations in Alaska fall in this zone. It does not set planting dates; see the frost calendar below for that.

Where in Alaska's zone 2b is the growing season longest?

Lake Minchumina runs the longest season on this page at about 124 days; Chistochina is shortest at about 85 days — they share the same hardiness zone, but they sit at different weather stations, so their frost calendars differ.

When should I plant tomatoes in Alaska's zone 2b?

Using Lake Louise's frost dates (this page's median-season location): start seeds indoors about Apr 4 – Apr 18, then transplant outside about Jun 6 – Jun 13. Your own location in the table above may differ by a week or two — use the ZIP planner on the home page for your exact station's dates.

Does every location in Alaska's zone 2b have the same frost dates?

No — they do not all share a weather station, so frost dates vary by a week or more across the 11 locations listed (see the table above for each location's own dates).

USDA zone 2b in Alaska

−45 to −40 °F avg. annual extreme minimum · 11 locations in this group · NOAA 1991–2020 normals

USDA plant hardiness zone 2b covers 11 locations across Alaska (average annual extreme minimum −45 to −40 °F): Buckland, AK, Chistochina, AK, College, AK, Eagle, AK, Lake Louise, AK, Lake Minchumina, AK, and 5 more. Average last spring frost across this group ranges May 13 (Lake Minchumina) to June 10 (Point Lay), and growing seasons run 85–124 days (Chistochina to Lake Minchumina) — even within one state, because hardiness sets winter survival, not planting dates. The table below gives every Alaska location's own frost dates; the printable planting calendar uses Lake Louise, this group's median-season location.

USDA zone: 2b−45 to −40 °F
Last frost range: May 13–Jun 10avg, 32°F
First frost range: Aug 23–Sep 24avg, 32°F
Growing season range: 85–124days

Locations in this group

Every location below shares this zone and a nearby weather station, but keeps its own frost dates — find your town for its own numbers, or use the ZIP planner on the home page for an instant personalized answer.

Own frost dates per location.
Location	Also covers	Nearest station	Last frost	First frost	Season (days)
Buckland	Noorvik, Kiana	Kotzebue Ralph Wein Ap	Jun 5	Sep 24	110
Chistochina	—	Nabesna	Jun 4	Sep 1	85
College	—	College Obsy	May 18	Sep 6	111
Eagle	—	Eagle	May 29	Aug 23	86
Lake Louise *	—	Lake Susitna	May 30	Sep 4	95
Lake Minchumina	—	Minchumina	May 13	Sep 17	124
Nikolai	—	Farewell Lake	May 30	Sep 5	97
Point Lay	Wainwright	Kivalina Ap	Jun 10	Sep 11	92
Sleetmute	Nikolai	Mcgrath Ap	May 13	Sep 13	120
UtqiagÌvik	Anaktuvuk Pass	Bettles Ap	May 22	Aug 24	94
Venetie	—	Central #2	May 25	Aug 26	92

* Lake Louise is this group's median-season location — the calendar below is computed from its data.

Data: NOAA NCEI U.S. Climate Normals 1991–2020 (public domain) and USDA Plant Hardiness Zone Map 2023. Planting windows synthesized from U.S. Cooperative Extension guides.

Planting calendar (Lake Louise, representative)

Computed from Lake Louise's average frost dates — the median-season location in this Alaskazone 2b group. hatched = start seeds indoors, solid green = plant out, teal = a fall sowing, and the terracotta dot marks the estimated first harvest. Ranges are extension-guide planning guidance, not guarantees — your own location's dates may run a week or two earlier or later (see the table above).

Crop

JanFebMarAprMayJunJulAugSepOctNovDec

Tomato

Pepper

Cucumber

Summer squash / zucchini

Start indoors
Plant out
Fall sowing
First harvest

Planting windows for Lake Louise (Alaska, zone 2b), this group's representative location.
Crop	Frost tolerance	Start indoors	Plant out	First harvest	Fall planting	Season fit
Tomato	Tender	Apr 4 – Apr 18	Jun 6 – Jun 13	Aug 5 – Aug 25	—	matures, but with little margin
Pepper	Very tender	Mar 21 – Apr 4	Jun 13 – Jun 20	Aug 12 – Sep 11	—	needs season extension (cold frame, row cover, or transplants) to mature
Cucumber	Tender	May 2 – May 9	Jun 6 – Jun 13	Jul 26 – Aug 15	—	matures comfortably
Summer squash / zucchini	Tender	—	Jun 6 – Jun 13	Jul 21 – Aug 5	—	matures comfortably
Bush bean	Tender	—	Jun 6 – Jun 13	Jul 26 – Aug 5	Jul 6 – Jul 16	matures comfortably
Sweet corn	Tender	—	May 30 – Jun 13	Jul 29 – Aug 28	—	matures, but with little margin
Basil	Very tender	Apr 18 – May 2	Jun 6 – Jun 13	Jul 6 – Jul 21	—	matures comfortably
Lettuce	Half-hardy	Apr 18 – May 2	May 2 – May 16	Jun 16 – Jul 1	Jun 22 – Jul 7	matures comfortably
Pea	Hardy	—	Apr 18 – May 2	Jun 12 – Jun 27	Jun 12 – Jun 27	matures comfortably
Spinach	Hardy	—	Apr 18 – May 2	May 28 – Jun 7	Jul 2 – Jul 12	matures comfortably
Carrot	Half-hardy	—	May 9 – May 16	Jul 8 – Jul 28	Jun 2 – Jun 22	matures comfortably
Broccoli	Half-hardy	Apr 4 – Apr 18	May 2 – May 16	Jun 26 – Jul 16	Jun 7 – Jun 27	matures comfortably

Which crops fit this growing season

Using Lake Louise's own 95-day growing season (32°F, NOAA 1991–2020 median) against each crop's real days-to-maturity range: 9 of 12 crops mature here with comfortable margin, 2mature with little room to spare, and 1 needs season extension (starting indoors earlier, a cold frame, or row cover) to reliably reach harvest before the first fall frost. The tightest fits: tomato (+10 day margin), pepper (-7 day margin), sweet corn (+7 day margin). A different location in the table above with a longer or shorter season will get a different mix — the ZIP planner on the home page gives your own.

Frost & freeze dates (Lake Louise)

From NOAA's 1991–2020 Climate Normals at station USC00505397. The median (p50) is the average date; the 90%-safe column is the date the freeze has passed in about 9 years out of 10 — the conservative date to plant after or harvest before.

Freeze probabilities by temperature threshold (MM/DD, NOAA 1991–2020), Lake Louise.
Threshold	Last spring — avg	Last spring — 90%-safe	First fall — avg	First fall — 90%-safe	Season (days)
36°F	—	—	—	—	69
32°F (freeze)	May 30	Jun 9	Sep 4	Sep 18	95
28°F	May 19	May 31	Sep 17	Sep 28	118
24°F	May 10	May 22	Sep 26	Oct 9	136

Growing degree days

Growing degree days (GDD) accumulate warmth above a base temperature over the year — a better predictor of crop development than the calendar alone. This group's median GDD (base 50°F) across all 11 locations is 754; Lake Louise's own reading is shown below.

Annual growing degree days for Lake Louise (°F·days, NOAA 1991–2020).
Model	°F·days	Used for
Base 50°F (warm-season)	531	standard warm-season base (tomato, corn, beans)
Base 40°F (cool-season)	1,662	cool-season crops (brassicas, greens)

Hardiness zone 2b in Alaska

Zone 2b means an average annual extreme minimum winter temperature of about −45 to −40 °F on the USDA's 2023 map — the number that tells you which perennials, shrubs, and trees reliably survive an average winter here. It does not set your planting dates, which come from the frost calendar above. Alaska spans 16 hardiness zones in this dataset — see all Alaska locations for the full range, including zones1a, 1b, 2a, 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b.

Explore zone 2b in other states at zone 2b, or see all USDA hardiness zones.

Frequently asked questions

What does USDA hardiness zone 2b mean in Alaska?: Zone 2b means an average annual extreme minimum winter temperature of −45 to −40 °F — the standard USDA measure of which perennials survive winter. 11 locations in Alaska fall in this zone. It does not set planting dates; see the frost calendar below for that.
Where in Alaska's zone 2b is the growing season longest?: Lake Minchumina runs the longest season on this page at about 124 days; Chistochina is shortest at about 85 days — they share the same hardiness zone, but they sit at different weather stations, so their frost calendars differ.
When should I plant tomatoes in Alaska's zone 2b?: Using Lake Louise's frost dates (this page's median-season location): start seeds indoors about Apr 4 – Apr 18, then transplant outside about Jun 6 – Jun 13. Your own location in the table above may differ by a week or two — use the ZIP planner on the home page for your exact station's dates.
Does every location in Alaska's zone 2b have the same frost dates?: No — they do not all share a weather station, so frost dates vary by a week or more across the 11 locations listed (see the table above for each location's own dates).

Sources & method

Frost, freeze, growing-season, and growing-degree-day figures are NOAA NCEI U.S. Climate Normals 1991–2020, one reading per location's own nearest station (see the table above). The hardiness zone is the USDA Plant Hardiness Zone Map 2023, matched to each location's ZIP. Planting windows are computed by counting from the average last and first frost using per-crop offsets synthesized from U.S. Cooperative Extension guides — the full method and citations are on the methodology page.