When to plant in Alhambra, CA
USDA Zone 10aHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Alhambra, California — all computed from Alhambra's nearest NOAA weather station.
With only about -2 frost-free days, Alhambra has a short season — start heat-lovers indoors early, favor quick-maturing varieties, and use row cover to stretch both ends. In zone 10a, frost is a minor factor for Alhambra — most perennials thrive, and annual vegetables can go out early and stay late.
Frost probability
SAN GABRIEL FIRE DEPT · 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 Alhambra’s own odds, recorded at SAN GABRIEL FIRE DEPT.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Feb 20 | Jan 17 | Dec 20 | Dec 6 | Dec 26 | Jan 30 |
| 32°F | Jan 28 | Jan 4 | Dec 19 | Dec 18 | Jan 2 | Jan 26 |
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 Alhambra, 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.
Alhambra planting FAQ
When is the last spring frost in Alhambra, CA?
On average, the last spring frost in Alhambra is around January 4 (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 Alhambra, CA?
Expect Alhambra's first fall frost near January 2 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Alhambra in?
Alhambra is in USDA hardiness zone 10a. In zone 10a, winters are mild — many tender perennials overwinter here.
How long is the growing season in Alhambra?
Alhambra has about -2 frost-free days — a short growing season — between the average last spring frost (January 4) and first fall frost (January 2).
When should I plant tomatoes in Alhambra?
For Alhambra, sow tomatoes indoors about November 9–November 23 and move the seedlings out around January 11, after the last spring frost.
Never miss a window in Alhambra
An email when it’s time to start seeds, transplant, and sow — timed to Alhambra’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- South Pasadena · 3 km
- San Gabriel · 4 km
- Monterey Park · 4 km
- San Marino · 5 km
- Rosemead · 5 km
- East San Gabriel · 6 km
- East Los Angeles · 7 km
- Temple City · 8 km
Frost dates recorded at SAN GABRIEL FIRE DEPT, 3 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 Alhambra, CA — Frost Dates & Zone 10a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00047785. Retrieved from https://blissgarden.com/california/alhambra.