Modesto, California: planting zone & frost dates
Modesto 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 Feb 10 and the first fall frost around Nov 29.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | Feb 25 | Nov 20 |
| Typical planning date (30% risk) | Feb 10 | Nov 29 |
| Median (50%) | Jan 31 | Dec 5 |
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 MODESTO CITY CO AP, CA (USW00023258), 3.0 mi (4.9 km) from the city center and 13 ft lower than the city center (-4 m). Record used for the 1991–2020 normals: 20 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Modesto
All 8 ZIP codes covering Modesto are in zone 9b.
Vegetable planting calendar for Modesto
Dates are counted from the 30%-risk frost dates above (last frost Feb 10, first frost Nov 29). 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 16 – Dec 30 | Feb 17 – Mar 3 | — | — |
| Pepper | Dec 2 – Dec 16 | Feb 24 – Mar 10 | — | — |
| Lettuce Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 30 – Jan 13 | Jan 27 – Feb 17 | Jan 13 – Feb 24 | Sep 20 – Oct 18 |
| Green Beans | — | — | Feb 17 – Mar 24 | Sep 6 – Sep 20 |
| Sweet Corn | — | — | Feb 17 – Mar 17 | — |
| Zucchini & Summer Squash | Jan 13 – Jan 20 | Feb 17 – Mar 3 | Feb 17 – Mar 10 | Sep 6 – Sep 20 |
| Cucumber | Jan 13 – Jan 20 | Feb 24 – Mar 3 | Feb 17 – Mar 10 | Sep 6 – Sep 20 |
| Carrot Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 20 – Feb 24 | Sep 6 – Sep 20 |
| Onion Mild winters: fall and winter plantings are usually more reliable than spring. | Nov 18 – Dec 2 | Jan 13 – Jan 27 | — | — |
| Potato Mild winters: fall and winter plantings are usually more reliable than spring. | — | Jan 13 – Feb 3 | — | — |
| Basil | Dec 30 – Jan 13 | Feb 24 – Mar 10 | Feb 24 – Mar 17 | — |
| Spinach Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 30 – Jan 27 | Oct 4 – Nov 1 |
| Kale Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 16 – Dec 30 | Jan 13 – Feb 3 | Jan 13 – Feb 3 | Sep 20 – Oct 18 |
| Broccoli Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 16 – Dec 30 | Jan 27 – Feb 17 | — | Sep 6 – Sep 20 |
| Peas Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 30 – Jan 20 | Sep 20 – Oct 4 |
| Eggplant | Dec 2 – Dec 16 | Feb 24 – Mar 10 | — | — |
| Cabbage Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 16 – Dec 30 | Jan 13 – Jan 27 | — | Sep 6 – Sep 20 |
| Radish Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 6 – Feb 24 | Oct 18 – Nov 15 |
| Strawberry | — | Jan 13 – Feb 3 | — | — |
| Beets Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 20 – Mar 3 | Sep 20 – Oct 4 |
Nearby cities in California
- Manteca — zone 9b, last frost Feb 17, first frost Nov 24
- Stockton — zone 9b, last frost Feb 19, first frost Nov 28
- Tracy — zone 9b, last frost Mar 9, first frost Nov 20
- Merced — zone 9a, last frost Mar 19, first frost Nov 16
- Livermore — zone 9b, last frost Feb 28, first frost Nov 25
- 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
Modesto gardening questions
When is the last frost in Modesto, CA?
Plan around Feb 10. At NOAA's Modesto City County Airport, CA station, 3.0 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 31, and after Feb 25 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Jan 8. 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 Modesto, CA?
Start seeds indoors Dec 16 – Dec 30 and set transplants outside Feb 17 – Mar 3, once nights stay above 50°F and the soil is near 60°F. With about 292 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 Modesto?
About 312 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 279 days, and in 1 year in 10 it runs 343 days or more. In fall there is a 10% chance of frost by Nov 20 and a 30% chance by Nov 29. That ranks 66th longest of 84 California cities on this site.
When should I plant a fall garden in Modesto?
Count back from the first fall frost (Nov 29): transplant broccoli Sep 6 – Sep 20; sow kale Sep 20 – Oct 18; sow lettuce Sep 20 – Oct 18; sow radishes Oct 18 – Nov 15. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Dec 21. How the math works: succession and fall planting.
Did Modesto's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, Modesto 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 Modesto compare with Manteca, CA?
Both are in zone 9b. The typical last spring frost in Modesto (Feb 10) comes about 7 days earlier than in Manteca, CA (Feb 17), 16 miles away, and the first fall frost is Nov 29 versus Nov 24. The two cities use different NOAA stations.