Fairbanks, AK planting calendar
- USDA zone
- 2a−50 to −45 °F
- Last frost
- May 18avg, 32°F
- First frost
- Sep 6avg, 32°F
- Growing season
- 111days
Fairbanks, Alaska is in USDA plant hardiness zone 2a. Its average last spring frost is around May 18 and the first fall frost around September 6, giving a growing season of about 111 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.
Fairbanks planting calendar
Each crop's windows are counted from Fairbanks'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 | Mar 23 – Apr 6 | May 25 – Jun 1 | Jul 24 – Aug 13 | — |
| Pepper | Very tender | Mar 9 – Mar 23 | Jun 1 – Jun 8 | Jul 31 – Aug 30 | — |
| Cucumber | Tender | Apr 20 – Apr 27 | May 25 – Jun 1 | Jul 14 – Aug 3 | — |
| Summer squash / zucchini | Tender | — | May 25 – Jun 1 | Jul 9 – Jul 24 | — |
| Bush bean | Tender | — | May 25 – Jun 1 | Jul 14 – Jul 24 | Jul 8 – Jul 18 |
| Sweet corn | Tender | — | May 18 – Jun 1 | Jul 17 – Aug 16 | — |
| Basil | Very tender | Apr 6 – Apr 20 | May 25 – Jun 1 | Jun 24 – Jul 9 | — |
| Lettuce | Half-hardy | Apr 6 – Apr 20 | Apr 20 – May 4 | Jun 4 – Jun 19 | Jun 24 – Jul 9 |
| Pea | Hardy | — | Apr 6 – Apr 20 | May 31 – Jun 15 | Jun 14 – Jun 29 |
| Spinach | Hardy | — | Apr 6 – Apr 20 | May 16 – May 26 | Jul 4 – Jul 14 |
| Carrot | Half-hardy | — | Apr 27 – May 4 | Jun 26 – Jul 16 | Jun 4 – Jun 24 |
| Broccoli | Half-hardy | Mar 23 – Apr 6 | Apr 20 – May 4 | Jun 14 – Jul 4 | Jun 9 – Jun 29 |
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 USC00502107. 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 | May 31 | Jun 16 | Aug 26 | Sep 7 | 87 |
| 32°F (freeze) | May 18 | Jun 1 | Sep 6 | Sep 20 | 111 |
| 28°F | May 7 | May 22 | Sep 20 | Oct 1 | 133 |
| 24°F | Apr 30 | May 11 | Sep 30 | Oct 12 | 152 |
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) | 906 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 2,212 | cool-season crops (brassicas, greens) |
Hardiness zone 2a
Fairbanks sits in USDA plant hardiness zone 2a on the 2023 map — meaning its average annual extreme minimum winter temperature is about −50 to −45 °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 2a, or see all USDA hardiness zones.
Frequently asked questions
- What USDA hardiness zone is Fairbanks?
- Fairbanks, Alaska is in USDA plant hardiness zone 2a on the 2023 map (average annual extreme minimum temperature −50 to −45 °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 Fairbanks?
- The average (median) last spring frost at 32°F is around May 18, 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 1, so wait until then before setting out frost-tender plants if you want to be safe.
- When is the first fall frost in Fairbanks?
- The average first fall frost at 32°F is around September 6. That leaves a growing season of about 111 days between the average last spring and first fall frosts.
- When should I start tomatoes in Fairbanks?
- Start tomato seeds indoors about Mar 23 – Apr 6 and transplant them outside about May 25 – Jun 1, once the danger of frost has passed. Estimated first harvest is around Jul 24 – Aug 13.
- How long is the growing season in Fairbanks?
- About 111 days at the 32°F threshold (NOAA 1991–2020, median) — the span between the average last spring frost (~May 18) and the average first fall frost (~September 6). 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 USC00502107 (College Obsy, 11 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.