When to plant in Brentwood, CA
USDA Zone 9bEverything below — frost dates, hardiness zone, and what to plant when in Brentwood, California — is derived from the closest NOAA station with complete climate normals.
Brentwood enjoys a long ~341-day frost-free season — you can succession-sow, fit in a second crop, and grow long-season heat-lovers with room to spare. Zone 9b is warm enough that Brentwood can grow subtropical perennials, and the short (or absent) frost period barely limits the annual calendar.
The average last spring frost in Brentwood is now 15 days earlier than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
ANTIOCH PUMPING PLT #3 · 1991–2020The date the last spring and first fall frost occur, by threshold and probability. A 90% date is later in spring — and earlier in fall — than a 10% date; the 50% · 32°F row is what most gardeners plan around. These are Brentwood’s own odds, recorded at ANTIOCH PUMPING PLT #3.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Mar 12 | Feb 8 | Jan 11 | Nov 18 | Dec 4 | Dec 28 |
| 32°F | Feb 1 | Jan 12 | Dec 20 | Nov 29 | Dec 19 | Jan 12 |
| 28°F | Jan 22 | Jan 2 | Dec 16 | Dec 9 | Dec 29 | Jan 16 |
Download this table as CSV ↓ — every threshold and probability, plus this city’s planting-window dates.
What to plant now
TODAY · JULY 19Nothing new to sow or transplant outdoors in the next few weeks — a seasonal lull. Check the full-year calendar below for the next window.
Full-year planting calendar
Each bar is the exact window to take a planting action in Brentwood, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 20 km · complete 32°F normalsWhen stations disagree by more than a few days, that spread is real microclimate variation — elevation, water, urban heat. Judge which station best matches your own yard.
Brentwood planting FAQ
When is the last spring frost in Brentwood, CA?
Plan for the last spring frost in Brentwood around January 12 (the date it has a 50% chance of a 32°F freeze). Anything frost-sensitive should go out after it.
When is the first fall frost in Brentwood, CA?
In Brentwood, the first 32°F freeze of fall lands around December 19 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is Brentwood in?
Brentwood is in USDA hardiness zone 9b. In zone 9b, winters are mild — many tender perennials overwinter here.
How long is the growing season in Brentwood?
There are roughly 341 frost-free days in Brentwood (a long growing season), running from the average last frost around January 12 to the first fall frost near December 19.
When should I plant tomatoes in Brentwood?
In Brentwood, start tomato seeds indoors around November 17–December 1, then transplant seedlings outdoors around January 19 once the danger of frost has passed.
Never miss a window in Brentwood
An email when it’s time to start seeds, transplant, and sow — timed to Brentwood’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Oakley · 7 km
- Antioch · 8 km
- Discovery Bay · 11 km
- Pittsburg · 18 km
- Clayton · 19 km
- Blackhawk · 22 km
- Mountain House · 24 km
- Bay Point · 24 km
Frost dates recorded at ANTIOCH PUMPING PLT #3, 6 km from the city center · 1991–2020 NOAA climate normals · zone from the USDA/PRISM 2023 map. How we compute this.
BlissGarden. "When to Plant in Brentwood, CA — Frost Dates & Zone 9b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00040232. Retrieved from https://blissgarden.com/california/brentwood.