Rampart, AK planting calendar
- USDA zone
- 1b−55 to −50 °F
- Last frost
- May 29avg, 32°F
- First frost
- Aug 28avg, 32°F
- Growing season
- 89days
Rampart, Alaska is in USDA plant hardiness zone 1b. Its average last spring frost is around May 29 and the first fall frost around August 28, giving a growing season of about 89 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.
Rampart planting calendar
Each crop's windows are counted from Rampart'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 3 – Apr 17 | Jun 5 – Jun 12 | Aug 4 – Aug 24 | — |
| Pepper | Very tender | Mar 20 – Apr 3 | Jun 12 – Jun 19 | Aug 11 – Sep 10 | — |
| Cucumber | Tender | May 1 – May 8 | Jun 5 – Jun 12 | Jul 25 – Aug 14 | — |
| Summer squash / zucchini | Tender | — | Jun 5 – Jun 12 | Jul 20 – Aug 4 | — |
| Bush bean | Tender | — | Jun 5 – Jun 12 | Jul 25 – Aug 4 | Jun 29 – Jul 9 |
| Sweet corn | Tender | — | May 29 – Jun 12 | Jul 28 – Aug 27 | — |
| Basil | Very tender | Apr 17 – May 1 | Jun 5 – Jun 12 | Jul 5 – Jul 20 | — |
| Lettuce | Half-hardy | Apr 17 – May 1 | May 1 – May 15 | Jun 15 – Jun 30 | Jun 15 – Jun 30 |
| Pea | Hardy | — | Apr 17 – May 1 | Jun 11 – Jun 26 | Jun 5 – Jun 20 |
| Spinach | Hardy | — | Apr 17 – May 1 | May 27 – Jun 6 | Jun 25 – Jul 5 |
| Carrot | Half-hardy | — | May 8 – May 15 | Jul 7 – Jul 27 | May 26 – Jun 15 |
| Broccoli | Half-hardy | Apr 3 – Apr 17 | May 1 – May 15 | Jun 25 – Jul 15 | May 31 – Jun 20 |
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 USW00026529. 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 | — | — | — | — | 59 |
| 32°F (freeze) | May 29 | Jun 16 | Aug 28 | Sep 9 | 89 |
| 28°F | May 16 | May 30 | Sep 8 | Sep 25 | 114 |
| 24°F | May 8 | May 21 | Sep 22 | Oct 4 | 135 |
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) | 742 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 1,947 | cool-season crops (brassicas, greens) |
Hardiness zone 1b
Rampart sits in USDA plant hardiness zone 1b on the 2023 map — meaning its average annual extreme minimum winter temperature is about −55 to −50 °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 1b, or see all USDA hardiness zones.
Frequently asked questions
- What USDA hardiness zone is Rampart?
- Rampart, Alaska is in USDA plant hardiness zone 1b on the 2023 map (average annual extreme minimum temperature −55 to −50 °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 Rampart?
- The average (median) last spring frost at 32°F is around May 29, 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 16, so wait until then before setting out frost-tender plants if you want to be safe.
- When is the first fall frost in Rampart?
- The average first fall frost at 32°F is around August 28. That leaves a growing season of about 89 days between the average last spring and first fall frosts.
- When should I start tomatoes in Rampart?
- Start tomato seeds indoors about Apr 3 – Apr 17 and transplant them outside about Jun 5 – Jun 12, once the danger of frost has passed. Estimated first harvest is around Aug 4 – Aug 24.
- How long is the growing season in Rampart?
- About 89 days at the 32°F threshold (NOAA 1991–2020, median) — the span between the average last spring frost (~May 29) and the average first fall frost (~August 28). 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 USW00026529 (Tanana Calhoun Mem Ap, 2.6 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.