Concord, California: planting zone & frost dates
Concord 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 23 and the first fall frost around Dec 6.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | Feb 12 | Nov 28 |
| Typical planning date (30% risk) | Jan 23 | Dec 6 |
| Median (50%) | Jan 9 | 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 CONCORD BUCHANAN FLD, CA (USW00023254), 3.2 mi (5.2 km) from the city center and 141 ft lower than the city center (-43 m). Record used for the 1991–2020 normals: 17 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Concord
All 5 ZIP codes covering Concord are in zone 9b.
Vegetable planting calendar for Concord
Dates are counted from the 30%-risk frost dates above (last frost Jan 23, first frost Dec 6). 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 28 – Dec 12 | Jan 30 – Feb 13 | — | — |
| Pepper | Nov 14 – Nov 28 | Feb 6 – Feb 20 | — | — |
| Lettuce Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 12 – Dec 26 | Jan 9 – Jan 30 | Dec 26 – Feb 6 | Sep 27 – Oct 25 |
| Green Beans | — | — | Jan 30 – Mar 6 | Sep 13 – Sep 27 |
| Sweet Corn | — | — | Jan 30 – Feb 27 | — |
| Zucchini & Summer Squash | Dec 26 – Jan 2 | Jan 30 – Feb 13 | Jan 30 – Feb 20 | Sep 13 – Sep 27 |
| Cucumber | Dec 26 – Jan 2 | Feb 6 – Feb 13 | Jan 30 – Feb 20 | Sep 13 – Sep 27 |
| Carrot Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 2 – Feb 6 | Sep 13 – Sep 27 |
| Onion Mild winters: fall and winter plantings are usually more reliable than spring. | Oct 31 – Nov 14 | Dec 26 – Jan 9 | — | — |
| Potato Mild winters: fall and winter plantings are usually more reliable than spring. | — | Dec 26 – Jan 16 | — | — |
| Basil | Dec 12 – Dec 26 | Feb 6 – Feb 20 | Feb 6 – Feb 27 | — |
| Spinach Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 12 – Jan 9 | Oct 11 – Nov 8 |
| Kale Mild winters: fall and winter plantings are usually more reliable than spring. | Nov 28 – Dec 12 | Dec 26 – Jan 16 | Dec 26 – Jan 16 | Sep 27 – Oct 25 |
| Broccoli Mild winters: fall and winter plantings are usually more reliable than spring. | Nov 28 – Dec 12 | Jan 9 – Jan 30 | — | Sep 13 – Sep 27 |
| Peas Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 12 – Jan 2 | Sep 27 – Oct 11 |
| Eggplant | Nov 14 – Nov 28 | Feb 6 – Feb 20 | — | — |
| Cabbage Mild winters: fall and winter plantings are usually more reliable than spring. | Nov 28 – Dec 12 | Dec 26 – Jan 9 | — | Sep 13 – Sep 27 |
| Radish Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 19 – Feb 6 | Oct 25 – Nov 22 |
| Strawberry | — | Dec 26 – Jan 16 | — | — |
| Beets Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 2 – Feb 13 | Sep 27 – Oct 11 |
Nearby cities in California
- Pittsburg — zone 9b, last frost Jan 22, first frost Dec 10
- Antioch — zone 9b, last frost Jan 22, first frost Dec 10
- San Ramon — zone 9b, last frost Feb 28, first frost Nov 25
- Fairfield — zone 9b, last frost Jan 28, first frost Dec 7
- Vallejo — zone 9b, last frost Mar 25, first frost Nov 12
- Oakland — zone 10a, frost rare
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
Concord gardening questions
When is the last frost in Concord, CA?
Plan around Jan 23. At NOAA's Concord Buchanan Field, CA station, 3.2 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 9, and after Feb 12 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Dec 30. Springs here are erratic: 58 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 Concord, CA?
Start seeds indoors Nov 28 – Dec 12 and set transplants outside Jan 30 – Feb 13, once nights stay above 50°F and the soil is near 60°F. With about 317 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 Concord?
About 343 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 313 days, and in 1 year in 10 it runs 365 days or more. In fall there is a 10% chance of frost by Nov 28 and a 30% chance by Dec 6. That ranks 40th longest of 84 California cities on this site.
When should I plant a fall garden in Concord?
Count back from the first fall frost (Dec 6): transplant broccoli Sep 13 – Sep 27; sow kale Sep 27 – Oct 25; sow lettuce Sep 27 – Oct 25; sow radishes Oct 25 – Nov 22. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Dec 23. How the math works: succession and fall planting.
Did Concord's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, Concord 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 Concord compare with Pittsburg, CA?
Both are in zone 9b. The typical last spring frost in Concord (Jan 23) comes about the same time as in Pittsburg, CA (Jan 22), 6 miles away, and the first fall frost is Dec 6 versus Dec 10. The two cities use different NOAA stations.