San Diego, California: planting zone & frost dates
San Diego is in USDA plant hardiness zone 10b, where the average coldest winter night reaches 35 to 40°F (1.7 to 4.4°C). Frost is rare here.
Frost dates
Frost data comes from NOAA station SAN DIEGO MONTGOMERY FLD, CA (USW00003131), 0.2 mi (0.4 km) from the city center and 3 ft lower than the city center (-1 m). Record used for the 1991–2020 normals: 20 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across San Diego
San Diego spans more than one half-zone. Share of the city's land area by zone (via its 44 ZIP codes): 10b (81%), 10a (14%), 9b (3%), 11a (2%). The headline zone is the one covering the most land. Look up your ZIP for your exact zone.
ZIP codes in San Diego and their zones
| ZIP | Zone | Share of city land |
|---|---|---|
| 92131 | 10b | 11.7% |
| 92154 | 10b | 8.0% |
| 92130 | 10b | 5.7% |
| 92129 | 10a | 4.0% |
| 92121 | 10b | 3.8% |
| 92037 | 10b | 3.7% |
| 92126 | 10b | 3.6% |
| 92127 | 10a | 3.6% |
| 92128 | 10a | 3.6% |
| 92145 | 10b | 3.3% |
| 92124 | 10b | 3.0% |
| 92117 | 10b | 2.7% |
| 92111 | 10b | 2.6% |
| 92123 | 10b | 2.6% |
| 92027 | 9b | 2.5% |
| 92114 | 10b | 2.5% |
| 92120 | 10b | 2.4% |
| 92109 | 10b | 2.3% |
| 92119 | 10b | 2.0% |
| 92115 | 10b | 1.9% |
| 92105 | 10b | 1.8% |
| 92101 | 11a | 1.7% |
| 92106 | 10b | 1.7% |
| 92122 | 10b | 1.7% |
| 92025 | 10a | 1.6% |
| 92110 | 10b | 1.5% |
| 92102 | 10b | 1.4% |
| 92108 | 10b | 1.4% |
| 92113 | 10b | 1.4% |
| 92071 | 10a | 1.2% |
| 92103 | 10b | 1.1% |
| 92104 | 10b | 1.1% |
| 92139 | 10b | 1.1% |
| 92116 | 10b | 1.0% |
| 92107 | 10b | 0.9% |
| 92173 | 10b | 0.9% |
| 92093 | 10b | 0.3% |
| 92136 | 10b | 0.2% |
| 92140 | 11a | 0.2% |
| 92182 | 10b | 0.1% |
| 92092 | 10b | 0.0% |
| 92132 | 11a | 0.0% |
| 92147 | 11a | 0.0% |
| 92161 | 10b | 0.0% |
Vegetable planting calendar for San Diego
Windows below are for a frost-free climate: plant cool-season crops from fall through late winter and warm-season crops in late winter–spring, with a second warm-season round in late summer for some crops.
| Crop | Planting windows (frost-free climate) | |||
|---|---|---|---|---|
| Tomato | Jan 15 – Mar 31; Aug 1 – Sep 15 | |||
| Pepper | Feb 1 – Apr 15; Jul 15 – Aug 31 | |||
| Lettuce | Sep 15 – Feb 15 | |||
| Green Beans | Feb 15 – Apr 30; Aug 15 – Sep 30 | |||
| Sweet Corn | Feb 15 – Apr 15; Aug 1 – Aug 31 | |||
| Zucchini & Summer Squash | Feb 15 – Apr 15; Aug 1 – Sep 15 | |||
| Cucumber | Feb 15 – Apr 15; Aug 1 – Sep 15 | |||
| Carrot | Sep 1 – Feb 28 | |||
| Onion | Oct 15 – Jan 15 | |||
| Potato | Jan 1 – Feb 28; Sep 1 – Oct 15 | |||
| Basil | Mar 1 – Jun 30; Aug 15 – Sep 30 | |||
| Spinach | Oct 1 – Feb 15 | |||
| Kale | Sep 1 – Feb 15 | |||
| Broccoli | Sep 1 – Jan 15 | |||
| Peas | Oct 1 – Jan 31 | |||
| Eggplant | Feb 15 – Apr 30; Jul 15 – Aug 31 | |||
| Cabbage | Sep 1 – Jan 31 | |||
| Radish | Sep 15 – Mar 15 | |||
| Strawberry | Oct 1 – Nov 30 | |||
| Beets | Sep 15 – Feb 28 | |||
Nearby cities in California
- El Cajon — zone 10a, last frost Jan 21, first frost Dec 12
- Chula Vista — zone 10b, last frost Jan 17, first frost Dec 22
- San Marcos — zone 10a, last frost Jan 14, first frost Dec 23
- Escondido — zone 10a, last frost Jan 14, first frost Dec 23
- Carlsbad — zone 10a, frost rare
- Vista — zone 10a, last frost Feb 24, first frost Dec 24
More: all California cities · other zone 10b cities: San Francisco, CA, Long Beach, CA, Anaheim, CA, Irvine, CA, Santa Ana, CA, Chula Vista, CA, St. Petersburg, FL, Cape Coral, FL
San Diego gardening questions
Does it ever frost in San Diego, CA?
Rarely. From 1991 to 2020, NOAA's San Diego Montgomery Field, CA station, 0.2 mi from the city center, reached 32°F in only 6% of years — too seldom for NOAA to compute frost dates. Zone 10b means the coldest night of an average winter is 35 to 40°F (1.7 to 4.4°C), so frost is essentially unknown, though cool nights can slow tropical plants.
When should I plant tomatoes in San Diego, CA?
Without a frost season, plant by temperature: set out tomatoes Jan 15 – Mar 31 and Aug 1 – Sep 15. Fruit set drops when nights stay above about 75°F, so avoid timing harvests for the hottest weeks. More: tomato planting by zone.
When is the best time for lettuce and broccoli in San Diego?
Cool-season crops do best in the mild months: plant lettuce Sep 15 – Feb 15 and broccoli Sep 1 – Jan 15. Summer heat makes lettuce bolt and broccoli flower early.
Did San Diego's hardiness zone change on the 2023 map?
Yes. Most of San Diego was zone 10a on the 2012 map and is zone 10b on the 2023 map — half a zone warmer, like about 56% of U.S. ZIP codes. The shift comes from a newer 1991–2020 averaging period plus more weather stations and better mapping; it does not mean last frost comes earlier. Why the 2023 map is warmer.
Is all of San Diego in zone 10b?
No. Zone 10b covers about 81% of the city's land; the rest is in 10a (14%), 9b (3%), 11a (2%), measured across the city's 44 ZIP codes. Check your own ZIP code in the table above or with the ZIP lookup.
How does San Diego compare with El Cajon, CA?
San Diego is zone 10b and El Cajon is zone 10a. Frost is rare in San Diego, but El Cajon (10 miles away) has a typical last frost around Jan 21 — see El Cajon, CA.