Castella, CA 96017 planting calendar
- USDA zone
- 8b15 to 20 °F
- Last frost
- Apr 23avg, 32°F
- First frost
- Oct 27avg, 32°F
- Growing season
- 185days
Castella, California is in USDA plant hardiness zone 8b. Its average last spring frost is around April 23 and the first fall frost around October 27, giving a growing season of about 185 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.
Castella planting calendar
Each crop's windows are counted from Castella'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 | Feb 26 – Mar 12 | Apr 30 – May 7 | Jun 29 – Jul 19 | — |
| Pepper | Very tender | Feb 12 – Feb 26 | May 7 – May 14 | Jul 6 – Aug 5 | — |
| Cucumber | Tender | Mar 26 – Apr 2 | Apr 30 – May 7 | Jun 19 – Jul 9 | — |
| Summer squash / zucchini | Tender | — | Apr 30 – May 7 | Jun 14 – Jun 29 | — |
| Bush bean | Tender | — | Apr 30 – May 7 | Jun 19 – Jun 29 | Aug 28 – Sep 7 |
| Sweet corn | Tender | — | Apr 23 – May 7 | Jun 22 – Jul 22 | — |
| Basil | Very tender | Mar 12 – Mar 26 | Apr 30 – May 7 | May 30 – Jun 14 | — |
| Lettuce | Half-hardy | Mar 12 – Mar 26 | Mar 26 – Apr 9 | May 10 – May 25 | Aug 14 – Aug 29 |
| Pea | Hardy | — | Mar 12 – Mar 26 | May 6 – May 21 | Aug 4 – Aug 19 |
| Spinach | Hardy | — | Mar 12 – Mar 26 | Apr 21 – May 1 | Aug 24 – Sep 3 |
| Carrot | Half-hardy | — | Apr 2 – Apr 9 | Jun 1 – Jun 21 | Jul 25 – Aug 14 |
| Broccoli | Half-hardy | Feb 26 – Mar 12 | Mar 26 – Apr 9 | May 20 – Jun 9 | Jul 30 – Aug 19 |
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 USC00042574. 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 11 | Jun 3 | Oct 9 | Oct 24 | 149 |
| 32°F (freeze) | Apr 23 | May 12 | Oct 27 | Nov 10 | 185 |
| 28°F | Mar 31 | Apr 21 | Nov 12 | Dec 2 | 225 |
| 24°F | Feb 20 | Mar 28 | Dec 3 | Jan 3 | 285 |
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) | 2,829 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 5,342 | cool-season crops (brassicas, greens) |
Hardiness zone 8b
Castella 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 Castella?
- Castella, 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 Castella?
- The average (median) last spring frost at 32°F is around April 23, 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 12, so wait until then before setting out frost-tender plants if you want to be safe.
- When is the first fall frost in Castella?
- The average first fall frost at 32°F is around October 27. That leaves a growing season of about 185 days between the average last spring and first fall frosts.
- When should I start tomatoes in Castella?
- Start tomato seeds indoors about Feb 26 – Mar 12 and transplant them outside about Apr 30 – May 7, once the danger of frost has passed. Estimated first harvest is around Jun 29 – Jul 19.
- How long is the growing season in Castella?
- About 185 days at the 32°F threshold (NOAA 1991–2020, median) — the span between the average last spring frost (~April 23) and the average first fall frost (~October 27). 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 USC00042574 (Dunsmuir Trtmt Pl, 9 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.