San Diego, CA 92019 planting calendar
- USDA zone
- 10b35 to 40 °F
- Last frost
- Jan 6avg, 32°F
- First frost
- Dec 21avg, 32°F
- Growing season
- 350days
San Diego, California is in USDA plant hardiness zone 10b. Its average last spring frost is around January 6 and the first fall frost around December 21, giving a growing season of about 350 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.
San Diego planting calendar
Each crop's windows are counted from San Diego'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 | Jan 1 | Jan 13 – Jan 20 | Mar 14 – Apr 3 | — |
| Pepper | Very tender | Jan 1 | Jan 20 – Jan 27 | Mar 21 – Apr 20 | — |
| Cucumber | Tender | Jan 1 | Jan 13 – Jan 20 | Mar 4 – Mar 24 | — |
| Summer squash / zucchini | Tender | — | Jan 13 – Jan 20 | Feb 27 – Mar 14 | — |
| Bush bean | Tender | — | Jan 13 – Jan 20 | Mar 4 – Mar 14 | Oct 22 – Nov 1 |
| Sweet corn | Tender | — | Jan 6 – Jan 20 | Mar 7 – Apr 6 | — |
| Basil | Very tender | Jan 1 | Jan 13 – Jan 20 | Feb 12 – Feb 27 | — |
| Lettuce | Half-hardy | Jan 1 | Jan 1 | Feb 15 – Mar 2 | Oct 8 – Oct 23 |
| Pea | Hardy | — | Jan 1 | Feb 25 – Mar 12 | Sep 28 – Oct 13 |
| Spinach | Hardy | — | Jan 1 | Feb 10 – Feb 20 | Oct 18 – Oct 28 |
| Carrot | Half-hardy | — | Jan 1 | Mar 2 – Mar 22 | Sep 18 – Oct 8 |
| Broccoli | Half-hardy | Jan 1 | Jan 1 | Feb 25 – Mar 17 | Sep 23 – Oct 13 |
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 USC00042706. 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 | Feb 6 | Mar 3 | Dec 6 | Dec 29 | 300 |
| 32°F (freeze) | Jan 6 | Feb 7 | Dec 21 | Jan 15 | 350 |
| 28°F | Dec 31 | Jan 15 | Dec 30 | Jan 14 | 365 |
| 24°F | — | — | — | — | 365 |
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) | 5,564 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 9,194 | cool-season crops (brassicas, greens) |
Hardiness zone 10b
San Diego sits in USDA plant hardiness zone 10b on the 2023 map — meaning its average annual extreme minimum winter temperature is about 35 to 40 °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 10b, or see all USDA hardiness zones.
Frequently asked questions
- What USDA hardiness zone is San Diego?
- San Diego, California is in USDA plant hardiness zone 10b on the 2023 map (average annual extreme minimum temperature 35 to 40 °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 San Diego?
- The average (median) last spring frost at 32°F is around January 6, from NOAA's 1991–2020 climate normals at the nearest reporting station. Roughly one year in ten the last frost is as late as February 7, so wait until then before setting out frost-tender plants if you want to be safe.
- When is the first fall frost in San Diego?
- The average first fall frost at 32°F is around December 21. That leaves a growing season of about 350 days between the average last spring and first fall frosts.
- When should I start tomatoes in San Diego?
- Start tomato seeds indoors about Jan 1 and transplant them outside about Jan 13 – Jan 20, once the danger of frost has passed. Estimated first harvest is around Mar 14 – Apr 3.
- How long is the growing season in San Diego?
- About 350 days at the 32°F threshold (NOAA 1991–2020, median) — the span between the average last spring frost (~January 6) and the average first fall frost (~December 21). 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 USC00042706 (El Cajon, 5.8 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.