Alta, CA 95701 planting calendar
- USDA zone
- 8b15 to 20 °F
- Last frost
- May 4avg, 32°F
- First frost
- Nov 4avg, 32°F
- Growing season
- 183days
Alta, California is in USDA plant hardiness zone 8b. Its average last spring frost is around May 4 and the first fall frost around November 4, giving a growing season of about 183 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.
Alta planting calendar
Each crop's windows are counted from Alta'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 9 – Mar 23 | May 11 – May 18 | Jul 10 – Jul 30 | — |
| Pepper | Very tender | Feb 23 – Mar 9 | May 18 – May 25 | Jul 17 – Aug 16 | — |
| Cucumber | Tender | Apr 6 – Apr 13 | May 11 – May 18 | Jun 30 – Jul 20 | — |
| Summer squash / zucchini | Tender | — | May 11 – May 18 | Jun 25 – Jul 10 | — |
| Bush bean | Tender | — | May 11 – May 18 | Jun 30 – Jul 10 | Sep 5 – Sep 15 |
| Sweet corn | Tender | — | May 4 – May 18 | Jul 3 – Aug 2 | — |
| Basil | Very tender | Mar 23 – Apr 6 | May 11 – May 18 | Jun 10 – Jun 25 | — |
| Lettuce | Half-hardy | Mar 23 – Apr 6 | Apr 6 – Apr 20 | May 21 – Jun 5 | Aug 22 – Sep 6 |
| Pea | Hardy | — | Mar 23 – Apr 6 | May 17 – Jun 1 | Aug 12 – Aug 27 |
| Spinach | Hardy | — | Mar 23 – Apr 6 | May 2 – May 12 | Sep 1 – Sep 11 |
| Carrot | Half-hardy | — | Apr 13 – Apr 20 | Jun 12 – Jul 2 | Aug 2 – Aug 22 |
| Broccoli | Half-hardy | Mar 9 – Mar 23 | Apr 6 – Apr 20 | May 31 – Jun 20 | Aug 7 – Aug 27 |
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 USW00023225. 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 22 | Jun 10 | Oct 20 | Nov 10 | 153 |
| 32°F (freeze) | May 4 | May 31 | Nov 4 | Nov 26 | 183 |
| 28°F | Apr 16 | May 13 | Nov 23 | Dec 15 | 219 |
| 24°F | Mar 29 | Apr 25 | Dec 10 | Jan 15 | 259 |
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) | 2,671 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 5,021 | cool-season crops (brassicas, greens) |
Hardiness zone 8b
Alta sits in USDA plant hardiness zone 8b on the 2023 map — meaning its average annual extreme minimum winter temperature is about 15 to 20 °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 8b, or see all USDA hardiness zones.
Frequently asked questions
- What USDA hardiness zone is Alta?
- Alta, California is in USDA plant hardiness zone 8b on the 2023 map (average annual extreme minimum temperature 15 to 20 °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 Alta?
- The average (median) last spring frost at 32°F is around May 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 May 31, so wait until then before setting out frost-tender plants if you want to be safe.
- When is the first fall frost in Alta?
- The average first fall frost at 32°F is around November 4. That leaves a growing season of about 183 days between the average last spring and first fall frosts.
- When should I start tomatoes in Alta?
- Start tomato seeds indoors about Mar 9 – Mar 23 and transplant them outside about May 11 – May 18, once the danger of frost has passed. Estimated first harvest is around Jul 10 – Jul 30.
- How long is the growing season in Alta?
- About 183 days at the 32°F threshold (NOAA 1991–2020, median) — the span between the average last spring frost (~May 4) and the average first fall frost (~November 4). 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 USW00023225 (Blue Canyon Ap, 7.5 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.