When to plant in Rosemont, CA
USDA Zone 9bRosemont, California frost dates, USDA zone, and a full-year planting calendar, drawn from the nearest NOAA station and tuned to the local season.
Rosemont enjoys a long ~338-day frost-free season — you can succession-sow, fit in a second crop, and grow long-season heat-lovers with room to spare. In zone 9b, frost is a minor factor for Rosemont — most perennials thrive, and annual vegetables can go out early and stay late.
The average last spring frost in Rosemont is now 7 days earlier than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
SACRAMENTO 5 ESE · 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 Rosemont’s own odds, recorded at SACRAMENTO 5 ESE.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Mar 11 | Feb 12 | Jan 9 | Nov 15 | Dec 1 | Dec 29 |
| 32°F | Feb 8 | Jan 12 | Dec 18 | Nov 28 | Dec 16 | Jan 14 |
| 28°F | Jan 22 | Dec 31 | Dec 13 | Dec 5 | Dec 25 | Jan 14 |
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 Rosemont, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 26 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.
Rosemont planting FAQ
When is the last spring frost in Rosemont, CA?
Plan for the last spring frost in Rosemont 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 Rosemont, CA?
The first fall frost in Rosemont typically arrives around December 16 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is Rosemont in?
Rosemont is in USDA hardiness zone 9b. In zone 9b, winters are mild — many tender perennials overwinter here.
How long is the growing season in Rosemont?
Rosemont has about 338 frost-free days — a long growing season — between the average last spring frost (January 12) and first fall frost (December 16).
When should I plant tomatoes in Rosemont?
For Rosemont, sow tomatoes indoors about November 17–December 1 and move the seedlings out around January 19, after the last spring frost.
Never miss a window in Rosemont
An email when it’s time to start seeds, transplant, and sow — timed to Rosemont’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- La Riviera · 2 km
- Arden-Arcade · 6 km
- Florin · 8 km
- Vineyard · 9 km
- Lemon Hill · 9 km
- Carmichael · 10 km
- Parkway · 10 km
- Sacramento · 10 km
Frost dates recorded at SACRAMENTO 5 ESE, 5 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 Rosemont, CA — Frost Dates & Zone 9b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USW00023271. Retrieved from https://blissgarden.com/california/rosemont.