San Ramon, California: planting zone & frost dates
San Ramon 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 28 and the first fall frost around Nov 25.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | Mar 13 | Nov 16 |
| Typical planning date (30% risk) | Feb 28 | Nov 25 |
| Median (50%) | Feb 15 | Dec 2 |
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 LIVERMORE, CA (USC00044997), 8.1 mi (13.1 km) from the city center and 289 ft lower than the city center (-88 m). Record used for the 1991–2020 normals: 27 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across San Ramon
All 2 ZIP codes covering San Ramon are in zone 9b.
Vegetable planting calendar for San Ramon
Dates are counted from the 30%-risk frost dates above (last frost Feb 28, first frost Nov 25). 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 3 – Jan 17 | Mar 7 – Mar 21 | — | — |
| Pepper | Dec 20 – Jan 3 | Mar 14 – Mar 28 | — | — |
| Lettuce Mild winters: fall and winter plantings are usually more reliable than spring. | Jan 17 – Jan 31 | Feb 14 – Mar 7 | Jan 31 – Mar 14 | Sep 16 – Oct 14 |
| Green Beans | — | — | Mar 7 – Apr 11 | Sep 2 – Sep 16 |
| Sweet Corn | — | — | Mar 7 – Apr 4 | — |
| Zucchini & Summer Squash | Jan 31 – Feb 7 | Mar 7 – Mar 21 | Mar 7 – Mar 28 | Sep 2 – Sep 16 |
| Cucumber | Jan 31 – Feb 7 | Mar 14 – Mar 21 | Mar 7 – Mar 28 | Sep 2 – Sep 16 |
| Carrot Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Feb 7 – Mar 14 | Sep 2 – Sep 16 |
| Onion Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 6 – Dec 20 | Jan 31 – Feb 14 | — | — |
| Potato Mild winters: fall and winter plantings are usually more reliable than spring. | — | Jan 31 – Feb 21 | — | — |
| Basil | Jan 17 – Jan 31 | Mar 14 – Mar 28 | Mar 14 – Apr 4 | — |
| Spinach Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 17 – Feb 14 | Sep 30 – Oct 28 |
| Kale Mild winters: fall and winter plantings are usually more reliable than spring. | Jan 3 – Jan 17 | Jan 31 – Feb 21 | Jan 31 – Feb 21 | Sep 16 – Oct 14 |
| Broccoli Mild winters: fall and winter plantings are usually more reliable than spring. | Jan 3 – Jan 17 | Feb 14 – Mar 7 | — | Sep 2 – Sep 16 |
| Peas Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 17 – Feb 7 | Sep 16 – Sep 30 |
| Eggplant | Dec 20 – Jan 3 | Mar 14 – Mar 28 | — | — |
| Cabbage Mild winters: fall and winter plantings are usually more reliable than spring. | Jan 3 – Jan 17 | Jan 31 – Feb 14 | — | Sep 2 – Sep 16 |
| Radish Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 24 – Mar 14 | Oct 14 – Nov 11 |
| Strawberry | — | Jan 31 – Feb 21 | — | — |
| Beets Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Feb 7 – Mar 21 | Sep 16 – Sep 30 |
Nearby cities in California
- Livermore — zone 9b, last frost Feb 28, first frost Nov 25
- Concord — zone 9b, last frost Jan 23, first frost Dec 6
- Hayward — zone 10a, last frost Jan 12, first frost Dec 17
- San Leandro — zone 10a, last frost Jan 22, first frost Dec 10
- Antioch — zone 9b, last frost Jan 22, first frost Dec 10
- Pittsburg — 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
San Ramon gardening questions
When is the last frost in San Ramon, CA?
Plan around Feb 28. At NOAA's Livermore, CA station, 8.1 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 Feb 15, and after Mar 13 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Jan 10. Springs here are erratic: 60 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 San Ramon, CA?
Start seeds indoors Jan 3 – Jan 17 and set transplants outside Mar 7 – Mar 21, once nights stay above 50°F and the soil is near 60°F. With about 270 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 San Ramon?
About 292 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 257 days, and in 1 year in 10 it runs 330 days or more. In fall there is a 10% chance of frost by Nov 16 and a 30% chance by Nov 25. That ranks 71st longest of 84 California cities on this site.
When should I plant a fall garden in San Ramon?
Count back from the first fall frost (Nov 25): transplant broccoli Sep 2 – Sep 16; sow kale Sep 16 – Oct 14; sow lettuce Sep 16 – Oct 14; sow radishes Oct 14 – Nov 11. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Dec 18. How the math works: succession and fall planting.
Did San Ramon's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, San Ramon 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 San Ramon compare with San Leandro, CA?
San Ramon is zone 9b and San Leandro is zone 10a. The typical last spring frost in San Ramon (Feb 28) comes about 37 days later than in San Leandro, CA (Jan 22), 13 miles away, and the first fall frost is Nov 25 versus Dec 10. San Ramon sits about 664 ft higher, which explains part of the gap. The two cities use different NOAA stations.