Cooper Landing, AK planting calendar
- USDA zone
- 5a−20 to −15 °F
- Last frost
- Jun 12avg, 32°F
- First frost
- Sep 1avg, 32°F
- Growing season
- 78days
Cooper Landing, Alaska is in USDA plant hardiness zone 5a. Its average last spring frost is around June 12 and the first fall frost around September 1, giving a growing season of about 78 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.
Cooper Landing planting calendar
Each crop's windows are counted from Cooper Landing'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 17 – May 1 | Jun 19 – Jun 26 | Aug 18 – Sep 7 | — |
| Pepper | Very tender | Apr 3 – Apr 17 | Jun 26 – Jul 3 | Aug 25 – Sep 24 | — |
| Cucumber | Tender | May 15 – May 22 | Jun 19 – Jun 26 | Aug 8 – Aug 28 | — |
| Summer squash / zucchini | Tender | — | Jun 19 – Jun 26 | Aug 3 – Aug 18 | — |
| Bush bean | Tender | — | Jun 19 – Jun 26 | Aug 8 – Aug 18 | Jul 3 – Jul 13 |
| Sweet corn | Tender | — | Jun 12 – Jun 26 | Aug 11 – Sep 10 | — |
| Basil | Very tender | May 1 – May 15 | Jun 19 – Jun 26 | Jul 19 – Aug 3 | — |
| Lettuce | Half-hardy | May 1 – May 15 | May 15 – May 29 | Jun 29 – Jul 14 | Jun 19 – Jul 4 |
| Pea | Hardy | — | May 1 – May 15 | Jun 25 – Jul 10 | Jun 9 – Jun 24 |
| Spinach | Hardy | — | May 1 – May 15 | Jun 10 – Jun 20 | Jun 29 – Jul 9 |
| Carrot | Half-hardy | — | May 22 – May 29 | Jul 21 – Aug 10 | May 30 – Jun 19 |
| Broccoli | Half-hardy | Apr 17 – May 1 | May 15 – May 29 | Jul 9 – Jul 29 | Jun 4 – Jun 24 |
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 USC00502149. 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 | — | — | — | — | 47 |
| 32°F (freeze) | Jun 12 | Jul 2 | Sep 1 | Sep 17 | 78 |
| 28°F | May 26 | Jun 8 | Sep 15 | Sep 30 | 114 |
| 24°F | May 4 | May 23 | Sep 29 | Oct 16 | 147 |
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) | 613 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 1,969 | cool-season crops (brassicas, greens) |
Hardiness zone 5a
Cooper Landing sits in USDA plant hardiness zone 5a on the 2023 map — meaning its average annual extreme minimum winter temperature is about −20 to −15 °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 5a, or see all USDA hardiness zones.
Frequently asked questions
- What USDA hardiness zone is Cooper Landing?
- Cooper Landing, Alaska is in USDA plant hardiness zone 5a on the 2023 map (average annual extreme minimum temperature −20 to −15 °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 Cooper Landing?
- The average (median) last spring frost at 32°F is around June 12, from NOAA's 1991–2020 climate normals at the nearest reporting station. Roughly one year in ten the last frost is as late as July 2, so wait until then before setting out frost-tender plants if you want to be safe.
- When is the first fall frost in Cooper Landing?
- The average first fall frost at 32°F is around September 1. That leaves a growing season of about 78 days between the average last spring and first fall frosts.
- When should I start tomatoes in Cooper Landing?
- Start tomato seeds indoors about Apr 17 – May 1 and transplant them outside about Jun 19 – Jun 26, once the danger of frost has passed. Estimated first harvest is around Aug 18 – Sep 7.
- How long is the growing season in Cooper Landing?
- About 78 days at the 32°F threshold (NOAA 1991–2020, median) — the span between the average last spring frost (~June 12) and the average first fall frost (~September 1). 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 USC00502149 (Cooper Landing 5 W, 4.8 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.