Silver Gate, MT 59081 planting calendar
- USDA zone
- 4a−30 to −25 °F
- Last frost
- Jun 5avg, 32°F
- First frost
- Sep 14avg, 32°F
- Growing season
- 99days
Silver Gate, Montana is in USDA plant hardiness zone 4a. Its average last spring frost is around June 5 and the first fall frost around September 14, giving a growing season of about 99 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.
Silver Gate planting calendar
Each crop's windows are counted from Silver Gate'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 10 – Apr 24 | Jun 12 – Jun 19 | Aug 11 – Aug 31 | — |
| Pepper | Very tender | Mar 27 – Apr 10 | Jun 19 – Jun 26 | Aug 18 – Sep 17 | — |
| Cucumber | Tender | May 8 – May 15 | Jun 12 – Jun 19 | Aug 1 – Aug 21 | — |
| Summer squash / zucchini | Tender | — | Jun 12 – Jun 19 | Jul 27 – Aug 11 | — |
| Bush bean | Tender | — | Jun 12 – Jun 19 | Aug 1 – Aug 11 | Jul 16 – Jul 26 |
| Sweet corn | Tender | — | Jun 5 – Jun 19 | Aug 4 – Sep 3 | — |
| Basil | Very tender | Apr 24 – May 8 | Jun 12 – Jun 19 | Jul 12 – Jul 27 | — |
| Lettuce | Half-hardy | Apr 24 – May 8 | May 8 – May 22 | Jun 22 – Jul 7 | Jul 2 – Jul 17 |
| Pea | Hardy | — | Apr 24 – May 8 | Jun 18 – Jul 3 | Jun 22 – Jul 7 |
| Spinach | Hardy | — | Apr 24 – May 8 | Jun 3 – Jun 13 | Jul 12 – Jul 22 |
| Carrot | Half-hardy | — | May 15 – May 22 | Jul 14 – Aug 3 | Jun 12 – Jul 2 |
| Broccoli | Half-hardy | Apr 10 – Apr 24 | May 8 – May 22 | Jul 2 – Jul 22 | Jun 17 – Jul 7 |
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 USC00245961. 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 | — | — | — | — | 72 |
| 32°F (freeze) | Jun 5 | Jun 21 | Sep 14 | Sep 28 | 99 |
| 28°F | May 24 | Jun 11 | Sep 25 | Oct 10 | 122 |
| 24°F | May 10 | May 31 | Oct 4 | Oct 22 | 144 |
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) | 1,215 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 2,773 | cool-season crops (brassicas, greens) |
Hardiness zone 4a
Silver Gate sits in USDA plant hardiness zone 4a on the 2023 map — meaning its average annual extreme minimum winter temperature is about −30 to −25 °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 4a, or see all USDA hardiness zones.
Frequently asked questions
- What USDA hardiness zone is Silver Gate?
- Silver Gate, Montana is in USDA plant hardiness zone 4a on the 2023 map (average annual extreme minimum temperature −30 to −25 °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 Silver Gate?
- The average (median) last spring frost at 32°F is around June 5, 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 21, so wait until then before setting out frost-tender plants if you want to be safe.
- When is the first fall frost in Silver Gate?
- The average first fall frost at 32°F is around September 14. That leaves a growing season of about 99 days between the average last spring and first fall frosts.
- When should I start tomatoes in Silver Gate?
- Start tomato seeds indoors about Apr 10 – Apr 24 and transplant them outside about Jun 12 – Jun 19, once the danger of frost has passed. Estimated first harvest is around Aug 11 – Aug 31.
- How long is the growing season in Silver Gate?
- About 99 days at the 32°F threshold (NOAA 1991–2020, median) — the span between the average last spring frost (~June 5) and the average first fall frost (~September 14). 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 USC00245961 (Mystic Lake, 31.8 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.