Fairfield, California: planting zone & frost dates
Fairfield is in USDA plant hardiness zone 9b, where the average coldest winter night reaches 25 to 30°F (-3.9 to -1.1°C). The typical last spring frost is around Jan 28 and the first fall frost around Dec 7.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | Feb 16 | Nov 29 |
| Typical planning date (30% risk) | Jan 28 | Dec 7 |
| Median (50%) | Jan 15 | Dec 14 |
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 FAIRFIELD, CA (USC00042934), 2.1 mi (3.3 km) from the city center and 3 ft higher than the city center (+1 m). Record used for the 1991–2020 normals: 27 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Fairfield
All 4 ZIP codes covering Fairfield are in zone 9b.
Vegetable planting calendar for Fairfield
Dates are counted from the 30%-risk frost dates above (last frost Jan 28, first frost Dec 7). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Dec 3 – Dec 17 | Feb 4 – Feb 18 | — | — |
| Pepper | Nov 19 – Dec 3 | Feb 11 – Feb 25 | — | — |
| Lettuce Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 17 – Dec 31 | Jan 14 – Feb 4 | Dec 31 – Feb 11 | Sep 28 – Oct 26 |
| Green Beans | — | — | Feb 4 – Mar 11 | Sep 14 – Sep 28 |
| Sweet Corn | — | — | Feb 4 – Mar 4 | — |
| Zucchini & Summer Squash | Dec 31 – Jan 7 | Feb 4 – Feb 18 | Feb 4 – Feb 25 | Sep 14 – Sep 28 |
| Cucumber | Dec 31 – Jan 7 | Feb 11 – Feb 18 | Feb 4 – Feb 25 | Sep 14 – Sep 28 |
| Carrot Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 7 – Feb 11 | Sep 14 – Sep 28 |
| Onion Mild winters: fall and winter plantings are usually more reliable than spring. | Nov 5 – Nov 19 | Dec 31 – Jan 14 | — | — |
| Potato Mild winters: fall and winter plantings are usually more reliable than spring. | — | Dec 31 – Jan 21 | — | — |
| Basil | Dec 17 – Dec 31 | Feb 11 – Feb 25 | Feb 11 – Mar 4 | — |
| Spinach Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 17 – Jan 14 | Oct 12 – Nov 9 |
| Kale Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 3 – Dec 17 | Dec 31 – Jan 21 | Dec 31 – Jan 21 | Sep 28 – Oct 26 |
| Broccoli Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 3 – Dec 17 | Jan 14 – Feb 4 | — | Sep 14 – Sep 28 |
| Peas Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 17 – Jan 7 | Sep 28 – Oct 12 |
| Eggplant | Nov 19 – Dec 3 | Feb 11 – Feb 25 | — | — |
| Cabbage Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 3 – Dec 17 | Dec 31 – Jan 14 | — | Sep 14 – Sep 28 |
| Radish Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 24 – Feb 11 | Oct 26 – Nov 23 |
| Strawberry | — | Dec 31 – Jan 21 | — | — |
| Beets Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 7 – Feb 18 | Sep 28 – Oct 12 |
Nearby cities in California
- Vacaville — zone 9b, last frost Mar 3, first frost Nov 21
- Napa — zone 9b, last frost Feb 27, first frost Nov 28
- Vallejo — zone 9b, last frost Mar 25, first frost Nov 12
- Pittsburg — zone 9b, last frost Jan 22, first frost Dec 10
- Concord — zone 9b, last frost Jan 23, first frost Dec 6
- Antioch — zone 9b, last frost Jan 22, first frost Dec 10
More: all California cities · other zone 9b cities: Houston, TX, Phoenix, AZ, Jacksonville, FL, San Jose, CA, Fresno, CA, Sacramento, CA, Mesa, AZ, Bakersfield, CA
Fairfield gardening questions
When is the last frost in Fairfield, CA?
Plan around Jan 28. At NOAA's Fairfield, CA station, 2.1 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 15, and after Feb 16 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 Fairfield, CA?
Start seeds indoors Dec 3 – Dec 17 and set transplants outside Feb 4 – Feb 18, once nights stay above 50°F and the soil is near 60°F. With about 313 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 Fairfield?
About 336 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 296 days, and in 1 year in 10 it runs 365 days or more. In fall there is a 10% chance of frost by Nov 29 and a 30% chance by Dec 7. That ranks 49th longest of 84 California cities on this site.
When should I plant a fall garden in Fairfield?
Count back from the first fall frost (Dec 7): transplant broccoli Sep 14 – Sep 28; sow kale Sep 28 – Oct 26; sow lettuce Sep 28 – Oct 26; sow radishes Oct 26 – Nov 23. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Dec 24. How the math works: succession and fall planting.
Did Fairfield's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, Fairfield is zone 9b 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.
How does Fairfield compare with Vacaville, CA?
Both are in zone 9b. The typical last spring frost in Fairfield (Jan 28) comes about 34 days earlier than in Vacaville, CA (Mar 3), 8 miles away, and the first fall frost is Dec 7 versus Nov 21. The two cities use different NOAA stations.