When to plant in Castaic, CA
USDA Zone 10aHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Castaic, California — all computed from Castaic's nearest NOAA weather station.
Castaic's growing season is short at roughly -7 days, so succession planting is limited; lean on transplants over direct sowing for anything slow to mature. In zone 10a, frost is a minor factor for Castaic — most perennials thrive, and annual vegetables can go out early and stay late.
Frost probability
NEWHALL 5NW · 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 Castaic’s own odds, recorded at NEWHALL 5NW.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Apr 8 | Feb 22 | Dec 21 | Nov 23 | Dec 19 | Feb 8 |
| 32°F | Mar 10 | Jan 8 | Dec 8 | Nov 30 | Jan 1 | Feb 25 |
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 Castaic, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 31 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.
Castaic planting FAQ
When is the last spring frost in Castaic, CA?
Plan for the last spring frost in Castaic around January 8 (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 Castaic, CA?
In Castaic, the first 32°F freeze of fall lands around January 1 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is Castaic in?
Castaic is in USDA hardiness zone 10a. In zone 10a, winters are mild — many tender perennials overwinter here.
How long is the growing season in Castaic?
Castaic has about -7 frost-free days — a short growing season — between the average last spring frost (January 8) and first fall frost (January 1).
When should I plant tomatoes in Castaic?
For Castaic, sow tomatoes indoors about November 13–November 27 and move the seedlings out around January 15, after the last spring frost.
Never miss a window in Castaic
An email when it’s time to start seeds, transplant, and sow — timed to Castaic’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Stevenson Ranch · 11 km
- Santa Clarita · 14 km
- Simi Valley · 26 km
- Fillmore · 28 km
- San Fernando · 28 km
- Moorpark · 31 km
- Oak Park · 35 km
- Calabasas · 38 km
Frost dates recorded at NEWHALL 5NW, 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 Castaic, CA — Frost Dates & Zone 10a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00046161. Retrieved from https://blissgarden.com/california/castaic.