When to plant in Grass Valley, CA
USDA Zone 9aEverything below — frost dates, hardiness zone, and what to plant when in Grass Valley, California — is derived from the closest NOAA station with complete climate normals.
Zone 9a is warm enough that Grass Valley can grow subtropical perennials, and the short (or absent) frost period barely limits the annual calendar.
Frost probability
GRASS VALLEY #2 · 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 Grass Valley’s own odds, recorded at GRASS VALLEY #2.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 20 | Apr 28 | Apr 13 | Oct 11 | Oct 31 | Nov 13 |
| 32°F | Apr 30 | Apr 10 | Mar 17 | Oct 26 | Nov 13 | Dec 1 |
| 28°F | Apr 8 | Mar 9 | Jan 31 | Nov 11 | Dec 1 | Dec 21 |
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 Grass Valley, 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.
Grass Valley planting FAQ
When is the last spring frost in Grass Valley, CA?
Grass Valley's average last spring frost falls near April 10 — 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 Grass Valley, CA?
In Grass Valley, the first 32°F freeze of fall lands around November 13 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is Grass Valley in?
Grass Valley is in USDA hardiness zone 9a. In zone 9a, winters are mild — many tender perennials overwinter here.
How long is the growing season in Grass Valley?
There are roughly 217 frost-free days in Grass Valley (a long growing season), running from the average last frost around April 10 to the first fall frost near November 13.
When should I plant tomatoes in Grass Valley?
In Grass Valley, start tomato seeds indoors around February 13–February 27, then transplant seedlings outdoors around April 17 once the danger of frost has passed.
Never miss a window in Grass Valley
An email when it’s time to start seeds, transplant, and sow — timed to Grass Valley’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- North Auburn · 32 km
- Auburn · 36 km
- Linda · 44 km
- Lincoln · 44 km
- Olivehurst · 46 km
- Marysville · 46 km
- Rocklin · 49 km
- Yuba City · 52 km
Frost dates recorded at GRASS VALLEY #2, 2 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 Grass Valley, CA — Frost Dates & Zone 9a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00043573. Retrieved from https://blissgarden.com/california/grass-valley.