When to plant in Santa Rosa, CA
USDA Zone 9aHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Santa Rosa, California — all computed from Santa Rosa's nearest NOAA weather station.
With about 279 frost-free days, Santa Rosa supports back-to-back plantings; stagger sowings every few weeks to keep beds productive spring through fall. In zone 9a, frost is a minor factor for Santa Rosa — most perennials thrive, and annual vegetables can go out early and stay late.
The average last spring frost in Santa Rosa is now 12 days later than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
SANTA ROSA · 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 Santa Rosa’s own odds, recorded at SANTA ROSA.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Apr 25 | Apr 3 | Mar 6 | Oct 31 | Nov 14 | Dec 1 |
| 32°F | Mar 29 | Feb 25 | Jan 21 | Nov 10 | Dec 1 | Dec 24 |
| 28°F | Feb 24 | Jan 20 | Dec 22 | Nov 26 | Dec 16 | Jan 19 |
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 Santa Rosa, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 14 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.
Santa Rosa planting FAQ
When is the last spring frost in Santa Rosa, CA?
Santa Rosa's average last spring frost falls near February 25 — the 50% mark at 32°F in the 1991–2020 normals. Hold tender transplants until the risk has passed, then plant out.
When is the first fall frost in Santa Rosa, CA?
The first fall frost in Santa Rosa typically arrives around December 1 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is Santa Rosa in?
Santa Rosa is in USDA hardiness zone 9a. In zone 9a, winters are mild — many tender perennials overwinter here.
How long is the growing season in Santa Rosa?
Santa Rosa has about 279 frost-free days — a long growing season — between the average last spring frost (February 25) and first fall frost (December 1).
When should I plant tomatoes in Santa Rosa?
For Santa Rosa, sow tomatoes indoors about December 31–January 14 and move the seedlings out around March 4, after the last spring frost.
Never miss a window in Santa Rosa
An email when it’s time to start seeds, transplant, and sow — timed to Santa Rosa’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Rohnert Park · 11 km
- Windsor · 14 km
- Petaluma · 24 km
- Healdsburg · 24 km
- Sonoma · 28 km
- Napa · 39 km
- Novato · 42 km
- American Canyon · 49 km
Frost dates recorded at SANTA ROSA, 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 Santa Rosa, CA — Frost Dates & Zone 9a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00047965. Retrieved from https://blissgarden.com/california/santa-rosa.