Huntsville, UT planting calendar
- USDA zone
- 6a−10 to −5 °F
- Last frost
- Jun 4avg, 32°F
- First frost
- Sep 16avg, 32°F
- Growing season
- 102days
Huntsville, Utah is in USDA plant hardiness zone 6a. Its average last spring frost is around June 4 and the first fall frost around September 16, giving a growing season of about 102 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.
Huntsville planting calendar
Each crop's windows are counted from Huntsville'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 9 – Apr 23 | Jun 11 – Jun 18 | Aug 10 – Aug 30 | — |
| Pepper | Very tender | Mar 26 – Apr 9 | Jun 18 – Jun 25 | Aug 17 – Sep 16 | — |
| Cucumber | Tender | May 7 – May 14 | Jun 11 – Jun 18 | Jul 31 – Aug 20 | — |
| Summer squash / zucchini | Tender | — | Jun 11 – Jun 18 | Jul 26 – Aug 10 | — |
| Bush bean | Tender | — | Jun 11 – Jun 18 | Jul 31 – Aug 10 | Jul 18 – Jul 28 |
| Sweet corn | Tender | — | Jun 4 – Jun 18 | Aug 3 – Sep 2 | — |
| Basil | Very tender | Apr 23 – May 7 | Jun 11 – Jun 18 | Jul 11 – Jul 26 | — |
| Lettuce | Half-hardy | Apr 23 – May 7 | May 7 – May 21 | Jun 21 – Jul 6 | Jul 4 – Jul 19 |
| Pea | Hardy | — | Apr 23 – May 7 | Jun 17 – Jul 2 | Jun 24 – Jul 9 |
| Spinach | Hardy | — | Apr 23 – May 7 | Jun 2 – Jun 12 | Jul 14 – Jul 24 |
| Carrot | Half-hardy | — | May 14 – May 21 | Jul 13 – Aug 2 | Jun 14 – Jul 4 |
| Broccoli | Half-hardy | Apr 9 – Apr 23 | May 7 – May 21 | Jul 1 – Jul 21 | Jun 19 – Jul 9 |
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 USC00424135. 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 4 | Jun 22 | Sep 16 | Oct 1 | 102 |
| 28°F | May 13 | Jun 7 | Sep 28 | Oct 12 | 132 |
| 24°F | Apr 26 | May 16 | Oct 10 | Oct 25 | 166 |
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) | 2,082 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 4,019 | cool-season crops (brassicas, greens) |
Hardiness zone 6a
Huntsville sits in USDA plant hardiness zone 6a on the 2023 map — meaning its average annual extreme minimum winter temperature is about −10 to −5 °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 6a, or see all USDA hardiness zones.
Frequently asked questions
- What USDA hardiness zone is Huntsville?
- Huntsville, Utah is in USDA plant hardiness zone 6a on the 2023 map (average annual extreme minimum temperature −10 to −5 °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 Huntsville?
- The average (median) last spring frost at 32°F is around June 4, 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 22, so wait until then before setting out frost-tender plants if you want to be safe.
- When is the first fall frost in Huntsville?
- The average first fall frost at 32°F is around September 16. That leaves a growing season of about 102 days between the average last spring and first fall frosts.
- When should I start tomatoes in Huntsville?
- Start tomato seeds indoors about Apr 9 – Apr 23 and transplant them outside about Jun 11 – Jun 18, once the danger of frost has passed. Estimated first harvest is around Aug 10 – Aug 30.
- How long is the growing season in Huntsville?
- About 102 days at the 32°F threshold (NOAA 1991–2020, median) — the span between the average last spring frost (~June 4) and the average first fall frost (~September 16). 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 USC00424135 (Huntsville Monastery, 10.8 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.