Chico, California: planting zone & frost dates
Chico 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 Mar 15 and the first fall frost around Nov 10.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | Apr 2 | Nov 1 |
| Typical planning date (30% risk) | Mar 15 | Nov 10 |
| Median (50%) | Mar 4 | Nov 17 |
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 CHICO UNIV FARM, CA (USC00041715), 4.7 mi (7.6 km) from the city center and 56 ft lower than the city center (-17 m). Record used for the 1991–2020 normals: 13 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Chico
Chico spans more than one half-zone. Share of the city's land area by zone (via its 4 ZIP codes): 9b (100%), 9a (0%). The headline zone is the one covering the most land. Look up your ZIP for your exact zone.
Vegetable planting calendar for Chico
Dates are counted from the 30%-risk frost dates above (last frost Mar 15, first frost Nov 10). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Jan 18 – Feb 1 | Mar 22 – Apr 5 | — | — |
| Pepper | Jan 4 – Jan 18 | Mar 29 – Apr 12 | — | — |
| Lettuce | Feb 1 – Feb 15 | Mar 1 – Mar 22 | Feb 15 – Mar 29 | Sep 1 – Sep 29 |
| Green Beans | — | — | Mar 22 – Apr 26 | Aug 18 – Sep 1 |
| Sweet Corn | — | — | Mar 22 – Apr 19 | — |
| Zucchini & Summer Squash | Feb 15 – Feb 22 | Mar 22 – Apr 5 | Mar 22 – Apr 12 | Aug 18 – Sep 1 |
| Cucumber | Feb 15 – Feb 22 | Mar 29 – Apr 5 | Mar 22 – Apr 12 | Aug 18 – Sep 1 |
| Carrot | — | — | Feb 22 – Mar 29 | Aug 18 – Sep 1 |
| Onion | Dec 21 – Jan 4 | Feb 15 – Mar 1 | — | — |
| Potato | — | Feb 15 – Mar 8 | — | — |
| Basil | Feb 1 – Feb 15 | Mar 29 – Apr 12 | Mar 29 – Apr 19 | — |
| Spinach | — | — | Feb 1 – Mar 1 | Sep 15 – Oct 13 |
| Kale | Jan 18 – Feb 1 | Feb 15 – Mar 8 | Feb 15 – Mar 8 | Sep 1 – Sep 29 |
| Broccoli | Jan 18 – Feb 1 | Mar 1 – Mar 22 | — | Aug 18 – Sep 1 |
| Peas | — | — | Feb 1 – Feb 22 | Sep 1 – Sep 15 |
| Eggplant | Jan 4 – Jan 18 | Mar 29 – Apr 12 | — | — |
| Cabbage | Jan 18 – Feb 1 | Feb 15 – Mar 1 | — | Aug 18 – Sep 1 |
| Radish | — | — | Feb 8 – Mar 29 | Sep 29 – Oct 27 |
| Strawberry | — | Feb 15 – Mar 8 | — | — |
| Beets | — | — | Feb 22 – Apr 5 | Sep 1 – Sep 15 |
Nearby cities in California
- Redding — zone 9b, last frost Mar 17, first frost Nov 16
- Roseville — zone 9b, last frost Mar 5, first frost Nov 17
- Citrus Heights — zone 9b, last frost Jan 22, first frost Dec 7
- Sacramento — zone 9b, last frost Jan 22, first frost Dec 7
- Folsom — zone 9b, last frost Jan 22, first frost Dec 7
- Rancho Cordova — zone 9b, last frost Jan 22, first frost Dec 7
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
Chico gardening questions
When is the last frost in Chico, CA?
Plan around Mar 15. At NOAA's Chico Univ. Farm, CA station, 4.7 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 Mar 4, and after Apr 2 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Feb 5. Springs here are erratic: 53 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 Chico, CA?
Start seeds indoors Jan 18 – Feb 1 and set transplants outside Mar 22 – Apr 5, once nights stay above 50°F and the soil is near 60°F. That leaves 240 days between the 30% frost dates, enough for most varieties including 80–85-day slicers. More: tomato planting dates by zone.
How long is the growing season in Chico?
About 257 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 223 days, and in 1 year in 10 it runs 290 days or more. In fall there is a 10% chance of frost by Nov 1 and a 30% chance by Nov 10. That ranks 80th longest of 84 California cities on this site.
When should I plant a fall garden in Chico?
Count back from the first fall frost (Nov 10): transplant broccoli Aug 18 – Sep 1; sow kale Sep 1 – Sep 29; sow lettuce Sep 1 – Sep 29; sow radishes Sep 29 – Oct 27. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Dec 3. How the math works: succession and fall planting.
Did Chico's hardiness zone change on the 2023 map?
Yes. Most of Chico was zone 9a on the 2012 map and is zone 9b 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 Chico in zone 9b?
No. Zone 9b covers about 100% of the city's land; the rest is in 9a (0%), measured across the city's 4 ZIP codes. Check your own ZIP code in the table above or with the ZIP lookup.