Adak, AK planting calendar
- USDA zone
- 8b15 to 20 °F
- Last frost
- May 31avg, 32°F
- First frost
- Oct 5avg, 32°F
- Growing season
- 128days
Adak, Alaska is in USDA plant hardiness zone 8b. Its average last spring frost is around May 31 and the first fall frost around October 5, giving a growing season of about 128 days (NOAA 1991–2020 normals, 32°F, median). Start tender crops like tomatoes and peppers indoors weeks before the last frost and set them out afterward; sow hardy crops such as peas, spinach, and lettuce before it. The planner below turns those frost dates into a printable per-crop planting calendar.
Adak planting calendar
Each crop's windows are counted from Adak's average frost dates. 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.
- Start indoors
- Plant out
- Fall sowing
- First harvest
| Crop | Frost tolerance | Start indoors | Plant out | First harvest | Fall planting |
|---|---|---|---|---|---|
| Tomato | Tender | Apr 5 – Apr 19 | Jun 7 – Jun 14 | Aug 6 – Aug 26 | — |
| Pepper | Very tender | Mar 22 – Apr 5 | Jun 14 – Jun 21 | Aug 13 – Sep 12 | — |
| Cucumber | Tender | May 3 – May 10 | Jun 7 – Jun 14 | Jul 27 – Aug 16 | — |
| Summer squash / zucchini | Tender | — | Jun 7 – Jun 14 | Jul 22 – Aug 6 | — |
| Bush bean | Tender | — | Jun 7 – Jun 14 | Jul 27 – Aug 6 | Aug 6 – Aug 16 |
| Sweet corn | Tender | — | May 31 – Jun 14 | Jul 30 – Aug 29 | — |
| Basil | Very tender | Apr 19 – May 3 | Jun 7 – Jun 14 | Jul 7 – Jul 22 | — |
| Lettuce | Half-hardy | Apr 19 – May 3 | May 3 – May 17 | Jun 17 – Jul 2 | Jul 23 – Aug 7 |
| Pea | Hardy | — | Apr 19 – May 3 | Jun 13 – Jun 28 | Jul 13 – Jul 28 |
| Spinach | Hardy | — | Apr 19 – May 3 | May 29 – Jun 8 | Aug 2 – Aug 12 |
| Carrot | Half-hardy | — | May 10 – May 17 | Jul 9 – Jul 29 | Jul 3 – Jul 23 |
| Broccoli | Half-hardy | Apr 5 – Apr 19 | May 3 – May 17 | Jun 27 – Jul 17 | Jul 8 – Jul 28 |
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.
Frost & freeze dates
From NOAA's 1991–2020 Climate Normals at station USW00025628. 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 (p10 for spring, p90 for fall) — the conservative date to plant after or harvest before.
| Threshold | Last spring — avg | Last spring — 90%-safe | First fall — avg | First fall — 90%-safe | Season (days) |
|---|---|---|---|---|---|
| 36°F | — | — | — | — | 89 |
| 32°F (freeze) | May 31 | Jun 23 | Oct 5 | Oct 21 | 128 |
| 28°F | May 9 | May 29 | Oct 24 | Nov 12 | 166 |
| 24°F | Apr 25 | May 11 | Nov 13 | Dec 4 | 199 |
32°F is the standard "freeze" line that damages tender crops; lighter 36°F frost can nip the most cold-sensitive plants, while hardy crops shrug off light frost down toward 28°F. Use the threshold that matches what you are protecting.
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. Warm-season crops need a long, warm GDD total; a short, cool GDD total favors greens and brassicas.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 40 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 893 | cool-season crops (brassicas, greens) |
Hardiness zone 8b
Adak sits in USDA plant hardiness zone 8b on the 2023 map — meaning its average annual extreme minimum winter temperature is about 15 to 20 °F. That number 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.
Explore more places in zone 8b, or see all USDA hardiness zones.
Frequently asked questions
- What USDA hardiness zone is Adak?
- Adak, Alaska is in USDA plant hardiness zone 8b on the 2023 map (average annual extreme minimum temperature 15 to 20 °F) — from the USDA Plant Hardiness Zone Map 2023, matched to this location's ZIP. See the methodology page for sources.
- When is the last frost in Adak?
- The average (median) last spring frost at 32°F is around May 31, from NOAA's 1991–2020 climate normals at the nearest reporting station. Roughly one year in ten the last frost is as late as June 23, so wait until then before setting out frost-tender plants if you want to be safe.
- When is the first fall frost in Adak?
- The average first fall frost at 32°F is around October 5. That leaves a growing season of about 128 days between the average last spring and first fall frosts.
- When should I start tomatoes in Adak?
- Start tomato seeds indoors about Apr 5 – Apr 19 and transplant them outside about Jun 7 – Jun 14, once the danger of frost has passed. Estimated first harvest is around Aug 6 – Aug 26.
- How long is the growing season in Adak?
- About 128 days at the 32°F threshold (NOAA 1991–2020, median) — the span between the average last spring frost (~May 31) and the average first fall frost (~October 5). Cold-hardy crops extend usable time at both ends; frost-tender crops fit inside it.
Sources & method
Frost, freeze, growing-season, and growing-degree-day figures are NOAA NCEI U.S. Climate Normals 1991–2020 for station USW00025628 (St George Island Ap, 700.4 km away). The hardiness zone is the USDA Plant Hardiness Zone Map 2023, matched to this 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.