When to plant in Rohnert Park, CA
USDA Zone 9aHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Rohnert Park, California — all computed from Rohnert Park's nearest NOAA weather station.
A generous ~279-day season lets Rohnert Park gardeners direct-sow more and still ripen long-maturity crops like melons and winter squash. Zone 9a is warm enough that Rohnert Park can grow subtropical perennials, and the short (or absent) frost period barely limits the annual calendar.
The average last spring frost in Rohnert Park 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 Rohnert Park’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 Rohnert Park, 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.
Rohnert Park planting FAQ
When is the last spring frost in Rohnert Park, CA?
Rohnert Park'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 Rohnert Park, CA?
Expect Rohnert Park's first fall frost near December 1 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Rohnert Park in?
Rohnert Park is in USDA hardiness zone 9a. In zone 9a, winters are mild — many tender perennials overwinter here.
How long is the growing season in Rohnert Park?
There are roughly 279 frost-free days in Rohnert Park (a long growing season), running from the average last frost around February 25 to the first fall frost near December 1.
When should I plant tomatoes in Rohnert Park?
In Rohnert Park, start tomato seeds indoors around December 31–January 14, then transplant seedlings outdoors around March 4 once the danger of frost has passed.
Never miss a window in Rohnert Park
An email when it’s time to start seeds, transplant, and sow — timed to Rohnert Park’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Santa Rosa · 11 km
- Petaluma · 13 km
- Sonoma · 22 km
- Windsor · 24 km
- Novato · 32 km
- Healdsburg · 34 km
- Napa · 35 km
- San Anselmo · 42 km
Frost dates recorded at SANTA ROSA, 12 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 Rohnert Park, CA — Frost Dates & Zone 9a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00047965. Retrieved from https://blissgarden.com/california/rohnert-park.