When to plant in Casa de Oro-Mount Helix, CA
USDA Zone 10bHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Casa de Oro-Mount Helix, California — all computed from Casa de Oro-Mount Helix's nearest NOAA weather station.
With about 349 frost-free days, Casa de Oro-Mount Helix supports back-to-back plantings; stagger sowings every few weeks to keep beds productive spring through fall. In zone 10b, frost is a minor factor for Casa de Oro-Mount Helix — most perennials thrive, and annual vegetables can go out early and stay late.
The average last spring frost in Casa de Oro-Mount Helix is now 6 days earlier than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
EL CAJON · 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 Casa de Oro-Mount Helix’s own odds, recorded at EL CAJON.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Mar 3 | Feb 6 | Jan 6 | Nov 18 | Dec 6 | Dec 29 |
| 32°F | Feb 7 | Jan 6 | Dec 13 | Dec 1 | Dec 21 | Jan 15 |
| 28°F | Jan 15 | Dec 31 | Dec 8 | Dec 7 | Dec 30 | 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 Casa de Oro-Mount Helix, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 20 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.
Casa de Oro-Mount Helix planting FAQ
When is the last spring frost in Casa de Oro-Mount Helix, CA?
Plan for the last spring frost in Casa de Oro-Mount Helix around January 6 (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 Casa de Oro-Mount Helix, CA?
In Casa de Oro-Mount Helix, the first 32°F freeze of fall lands around December 21 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is Casa de Oro-Mount Helix in?
Casa de Oro-Mount Helix is in USDA hardiness zone 10b. In zone 10b, winters are mild — many tender perennials overwinter here.
How long is the growing season in Casa de Oro-Mount Helix?
Casa de Oro-Mount Helix has about 349 frost-free days — a long growing season — between the average last spring frost (January 6) and first fall frost (December 21).
When should I plant tomatoes in Casa de Oro-Mount Helix?
For Casa de Oro-Mount Helix, sow tomatoes indoors about November 11–November 25 and move the seedlings out around January 13, after the last spring frost.
Never miss a window in Casa de Oro-Mount Helix
An email when it’s time to start seeds, transplant, and sow — timed to Casa de Oro-Mount Helix’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Spring Valley · 4 km
- El Cajon · 4 km
- Rancho San Diego · 5 km
- La Mesa · 5 km
- Bostonia · 7 km
- La Presa · 7 km
- Lemon Grove · 7 km
- Winter Gardens · 9 km
Frost dates recorded at EL CAJON, 6 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 Casa de Oro-Mount Helix, CA — Frost Dates & Zone 10b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00042706. Retrieved from https://blissgarden.com/california/casa-de-oro-mount-helix.