When to plant in Sonoma, CA
USDA Zone 9bSonoma, California frost dates, USDA zone, and a full-year planting calendar, drawn from the nearest NOAA station and tuned to the local season.
Sonoma enjoys a long ~270-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 Sonoma can grow subtropical perennials, and the short (or absent) frost period barely limits the annual calendar.
Frost probability
SONOMA · 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 Sonoma’s own odds, recorded at SONOMA.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Apr 29 | Apr 8 | Mar 14 | Oct 25 | Nov 8 | Nov 26 |
| 32°F | Apr 5 | Mar 2 | Jan 27 | Nov 6 | Nov 27 | Dec 21 |
| 28°F | Feb 22 | Jan 20 | Dec 20 | Nov 24 | Dec 14 | Jan 17 |
Download this table as CSV ↓ — every threshold and probability, plus this city’s planting-window dates.
What to plant now
TODAY · JULY 19Full-year planting calendar
Each bar is the exact window to take a planting action in Sonoma, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 17 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.
Sonoma planting FAQ
When is the last spring frost in Sonoma, CA?
On average, the last spring frost in Sonoma is around March 2 (50% probability at 32°F, from 1991–2020 NOAA normals). Wait until after this date to set out tender plants like tomatoes and peppers.
When is the first fall frost in Sonoma, CA?
Expect Sonoma's first fall frost near November 27 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Sonoma in?
Sonoma is in USDA hardiness zone 9b. In zone 9b, winters are mild — many tender perennials overwinter here.
How long is the growing season in Sonoma?
There are roughly 270 frost-free days in Sonoma (a long growing season), running from the average last frost around March 2 to the first fall frost near November 27.
When should I plant tomatoes in Sonoma?
In Sonoma, start tomato seeds indoors around January 5–January 19, then transplant seedlings outdoors around March 9 once the danger of frost has passed.
Never miss a window in Sonoma
An email when it’s time to start seeds, transplant, and sow — timed to Sonoma’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Napa · 14 km
- Petaluma · 16 km
- American Canyon · 21 km
- Rohnert Park · 22 km
- Novato · 24 km
- Vallejo · 27 km
- Santa Rosa · 28 km
- Hercules · 33 km
Frost dates recorded at SONOMA, 1 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 Sonoma, CA — Frost Dates & Zone 9b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00048351. Retrieved from https://blissgarden.com/california/sonoma.