Irvine, California: planting zone & frost dates
Irvine is in USDA plant hardiness zone 10b, where the average coldest winter night reaches 35 to 40°F (1.7 to 4.4°C). The typical last spring frost is around Jan 14 and the first fall frost around Dec 13.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | Feb 2 | Dec 3 |
| Typical planning date (30% risk) | Jan 14 | Dec 13 |
| Median (50%) | Jan 5 | Dec 25 |
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 TUSTIN IRVINE RCH, CA (USC00049087), 1.9 mi (3.1 km) from the city center and 92 ft higher than the city center (+28 m). Record used for the 1991–2020 normals: 13 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Irvine
Irvine spans more than one half-zone. Share of the city's land area by zone (via its 10 ZIP codes): 10b (86%), 10a (14%). The headline zone is the one covering the most land. Look up your ZIP for your exact zone.
Vegetable planting calendar for Irvine
Dates are counted from the 30%-risk frost dates above (last frost Jan 14, first frost Dec 13). 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 19 – Dec 3 | Jan 21 – Feb 4 | — | — |
| Pepper | Nov 5 – Nov 19 | Jan 28 – Feb 11 | — | — |
| Lettuce Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 3 – Dec 17 | Dec 31 – Jan 21 | Dec 17 – Jan 28 | Oct 4 – Nov 1 |
| Green Beans | — | — | Jan 21 – Feb 25 | Sep 20 – Oct 4 |
| Sweet Corn | — | — | Jan 21 – Feb 18 | — |
| Zucchini & Summer Squash | Dec 17 – Dec 24 | Jan 21 – Feb 4 | Jan 21 – Feb 11 | Sep 20 – Oct 4 |
| Cucumber | Dec 17 – Dec 24 | Jan 28 – Feb 4 | Jan 21 – Feb 11 | Sep 20 – Oct 4 |
| Carrot Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 24 – Jan 28 | Sep 20 – Oct 4 |
| Onion Mild winters: fall and winter plantings are usually more reliable than spring. | Oct 22 – Nov 5 | Dec 17 – Dec 31 | — | — |
| Potato Mild winters: fall and winter plantings are usually more reliable than spring. | — | Dec 17 – Jan 7 | — | — |
| Basil | Dec 3 – Dec 17 | Jan 28 – Feb 11 | Jan 28 – Feb 18 | — |
| Spinach Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 3 – Dec 31 | Oct 18 – Nov 15 |
| Kale Mild winters: fall and winter plantings are usually more reliable than spring. | Nov 19 – Dec 3 | Dec 17 – Jan 7 | Dec 17 – Jan 7 | Oct 4 – Nov 1 |
| Broccoli Mild winters: fall and winter plantings are usually more reliable than spring. | Nov 19 – Dec 3 | Dec 31 – Jan 21 | — | Sep 20 – Oct 4 |
| Peas Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 3 – Dec 24 | Oct 4 – Oct 18 |
| Eggplant | Nov 5 – Nov 19 | Jan 28 – Feb 11 | — | — |
| Cabbage Mild winters: fall and winter plantings are usually more reliable than spring. | Nov 19 – Dec 3 | Dec 17 – Dec 31 | — | Sep 20 – Oct 4 |
| Radish Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 10 – Jan 28 | Nov 1 – Nov 29 |
| Strawberry | — | Dec 17 – Jan 7 | — | — |
| Beets Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 24 – Feb 4 | Oct 4 – Oct 18 |
Nearby cities in California
- Tustin — zone 10a, frost rare
- Lake Forest — zone 10b, frost rare
- Santa Ana — zone 10b, frost rare
- Mission Viejo — zone 10b, frost rare
- Orange — zone 10b, frost rare
- Costa Mesa — zone 10b, frost rare
More: all California cities · other zone 10b cities: San Diego, CA, San Francisco, CA, Long Beach, CA, Anaheim, CA, Santa Ana, CA, Chula Vista, CA, St. Petersburg, FL, Cape Coral, FL
Irvine gardening questions
When is the last frost in Irvine, CA?
Plan around Jan 14. At NOAA's Tustin Irvine Rch, 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 5, and after Feb 2 the risk drops to about 1 in 10. Springs here are erratic: 50 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 Irvine, CA?
Start seeds indoors Nov 19 – Dec 3 and set transplants outside Jan 21 – Feb 4, once nights stay above 50°F and the soil is near 60°F. With about 333 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 Irvine?
About 365 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 331 days, and in 1 year in 10 it runs 365 days or more. In fall there is a 10% chance of frost by Dec 3 and a 30% chance by Dec 13. That is the longest of the 84 California cities on this site.
When should I plant a fall garden in Irvine?
Count back from the first fall frost (Dec 13): transplant broccoli Sep 20 – Oct 4; sow kale Oct 4 – Nov 1; sow lettuce Oct 4 – Nov 1; sow radishes Nov 1 – Nov 29. How the math works: succession and fall planting.
Did Irvine's hardiness zone change on the 2023 map?
Yes. Most of Irvine 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 Irvine in zone 10b?
No. Zone 10b covers about 86% of the city's land; the rest is in 10a (14%), measured across the city's 10 ZIP codes. Check your own ZIP code in the table above or with the ZIP lookup.