El Cajon, California: planting zone & frost dates
El Cajon is in USDA plant hardiness zone 10a, where the average coldest winter night reaches 30 to 35°F (-1.1 to 1.7°C). The typical last spring frost is around Jan 21 and the first fall frost around Dec 12.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | Feb 7 | Dec 1 |
| Typical planning date (30% risk) | Jan 21 | Dec 12 |
| Median (50%) | Jan 6 | Dec 21 |
How to read this: after the spring "10% risk" date, a 32°F frost happens in only about 1 year in 10. In fall, the "10% risk" date is the early end — a frost before it happens about 1 year in 10.
Frost data comes from NOAA station EL CAJON, CA (USC00042706), 1.9 mi (3.0 km) from the city center and 69 ft higher than the city center (+21 m). Record used for the 1991–2020 normals: 27 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across El Cajon
El Cajon spans more than one half-zone. Share of the city's land area by zone (via its 4 ZIP codes): 10a (84%), 10b (16%). The headline zone is the one covering the most land. Look up your ZIP for your exact zone.
Vegetable planting calendar for El Cajon
Dates are counted from the 30%-risk frost dates above (last frost Jan 21, first frost Dec 12). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Nov 26 – Dec 10 | Jan 28 – Feb 11 | — | — |
| Pepper | Nov 12 – Nov 26 | Feb 4 – Feb 18 | — | — |
| Lettuce Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 10 – Dec 24 | Jan 7 – Jan 28 | Dec 24 – Feb 4 | Oct 3 – Oct 31 |
| Green Beans | — | — | Jan 28 – Mar 4 | Sep 19 – Oct 3 |
| Sweet Corn | — | — | Jan 28 – Feb 25 | — |
| Zucchini & Summer Squash | Dec 24 – Dec 31 | Jan 28 – Feb 11 | Jan 28 – Feb 18 | Sep 19 – Oct 3 |
| Cucumber | Dec 24 – Dec 31 | Feb 4 – Feb 11 | Jan 28 – Feb 18 | Sep 19 – Oct 3 |
| Carrot Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 31 – Feb 4 | Sep 19 – Oct 3 |
| Onion Mild winters: fall and winter plantings are usually more reliable than spring. | Oct 29 – Nov 12 | Dec 24 – Jan 7 | — | — |
| Potato Mild winters: fall and winter plantings are usually more reliable than spring. | — | Dec 24 – Jan 14 | — | — |
| Basil | Dec 10 – Dec 24 | Feb 4 – Feb 18 | Feb 4 – Feb 25 | — |
| Spinach Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 10 – Jan 7 | Oct 17 – Nov 14 |
| Kale Mild winters: fall and winter plantings are usually more reliable than spring. | Nov 26 – Dec 10 | Dec 24 – Jan 14 | Dec 24 – Jan 14 | Oct 3 – Oct 31 |
| Broccoli Mild winters: fall and winter plantings are usually more reliable than spring. | Nov 26 – Dec 10 | Jan 7 – Jan 28 | — | Sep 19 – Oct 3 |
| Peas Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 10 – Dec 31 | Oct 3 – Oct 17 |
| Eggplant | Nov 12 – Nov 26 | Feb 4 – Feb 18 | — | — |
| Cabbage Mild winters: fall and winter plantings are usually more reliable than spring. | Nov 26 – Dec 10 | Dec 24 – Jan 7 | — | Sep 19 – Oct 3 |
| Radish Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 17 – Feb 4 | Oct 31 – Nov 28 |
| Strawberry | — | Dec 24 – Jan 14 | — | — |
| Beets Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 31 – Feb 11 | Oct 3 – Oct 17 |
Nearby cities in California
- San Diego — zone 10b, frost rare
- Chula Vista — zone 10b, last frost Jan 17, first frost Dec 22
- Escondido — zone 10a, last frost Jan 14, first frost Dec 23
- San Marcos — 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 10a cities: Los Angeles, CA, Oakland, CA, Tampa, FL, Orlando, FL, Riverside, CA, Corpus Christi, TX, Port St. Lucie, FL, Scottsdale, AZ
El Cajon gardening questions
When is the last frost in El Cajon, CA?
Plan around Jan 21. At NOAA's El Cajon, CA station, 1.9 mi from the city center, there is a 30% chance of a 32°F frost after that date. Half of springs have their last frost by Jan 6, and after Feb 7 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Dec 31. Springs here are erratic: 56 days separate the 90% and 10% dates, versus a median of 36 days for cities on this site, so watch the forecast rather than the calendar.
When should I plant tomatoes in El Cajon, CA?
Start seeds indoors Nov 26 – Dec 10 and set transplants outside Jan 28 – Feb 11, once nights stay above 50°F and the soil is near 60°F. With about 325 frost-free days, frost is not the main limit — fruit set drops when nights stay above about 75°F, so early plantings tend to do best. More: tomato planting dates by zone.
How long is the growing season in El Cajon?
About 350 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 317 days, and in 1 year in 10 it runs 365 days or more. In fall there is a 10% chance of frost by Dec 1 and a 30% chance by Dec 12. That ranks 37th longest of 84 California cities on this site.
When should I plant a fall garden in El Cajon?
Count back from the first fall frost (Dec 12): transplant broccoli Sep 19 – Oct 3; sow kale Oct 3 – Oct 31; sow lettuce Oct 3 – Oct 31; sow radishes Oct 31 – Nov 28. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Dec 30. How the math works: succession and fall planting.
Did El Cajon's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, El Cajon is zone 10a on both the 2012 and the 2023 USDA maps (PRISM/OSU ZIP listings). About 42% of U.S. ZIP codes kept their half-zone in 2023. Why the 2023 map is warmer.
Is all of El Cajon in zone 10a?
No. Zone 10a covers about 84% of the city's land; the rest is in 10b (16%), measured across the city's 4 ZIP codes. Check your own ZIP code in the table above or with the ZIP lookup.