When to plant in Walnut, CA
USDA Zone 10aEverything below — frost dates, hardiness zone, and what to plant when in Walnut, California — is derived from the closest NOAA station with complete climate normals.
A generous ~354-day season lets Walnut gardeners direct-sow more and still ripen long-maturity crops like melons and winter squash. Zone 10a is warm enough that Walnut can grow subtropical perennials, and the short (or absent) frost period barely limits the annual calendar.
Frost probability
POMONA/FAIRPLEX · 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 Walnut’s own odds, recorded at POMONA/FAIRPLEX.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Mar 9 | Feb 8 | Dec 29 | Nov 21 | Dec 10 | Dec 26 |
| 32°F | Feb 18 | Jan 8 | Dec 14 | Dec 5 | Dec 28 | Feb 2 |
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 Walnut, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 23 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.
Walnut planting FAQ
When is the last spring frost in Walnut, CA?
On average, the last spring frost in Walnut is around January 8 (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 Walnut, CA?
The first fall frost in Walnut typically arrives around December 28 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is Walnut in?
Walnut is in USDA hardiness zone 10a. In zone 10a, winters are mild — many tender perennials overwinter here.
How long is the growing season in Walnut?
There are roughly 354 frost-free days in Walnut (a long growing season), running from the average last frost around January 8 to the first fall frost near December 28.
When should I plant tomatoes in Walnut?
In Walnut, start tomato seeds indoors around November 13–November 27, then transplant seedlings outdoors around January 15 once the danger of frost has passed.
Never miss a window in Walnut
An email when it’s time to start seeds, transplant, and sow — timed to Walnut’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- South San Jose Hills · 5 km
- Diamond Bar · 5 km
- West Covina · 5 km
- Covina · 6 km
- Valinda · 7 km
- Rowland Heights · 8 km
- San Dimas · 9 km
- Pomona · 9 km
Frost dates recorded at POMONA/FAIRPLEX, 10 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 Walnut, CA — Frost Dates & Zone 10a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00047050. Retrieved from https://blissgarden.com/california/walnut.