When to plant in Imperial, CA
USDA Zone 10aImperial, California frost dates, USDA zone, and a full-year planting calendar, drawn from the nearest NOAA station and tuned to the local season.
A generous ~344-day season lets Imperial gardeners direct-sow more and still ripen long-maturity crops like melons and winter squash. Zone 10a is warm enough that Imperial can grow subtropical perennials, and the short (or absent) frost period barely limits the annual calendar.
Frost probability
IMPERIAL CO AP · 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 Imperial’s own odds, recorded at IMPERIAL CO AP.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Mar 1 | Feb 5 | Jan 9 | Nov 23 | Dec 8 | Dec 27 |
| 32°F | Feb 15 | Jan 14 | Dec 18 | Dec 2 | Dec 24 | Jan 24 |
| 28°F | Feb 7 | Jan 8 | Dec 18 | Dec 17 | Jan 5 | Feb 4 |
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 Imperial, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 8 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.
Imperial planting FAQ
When is the last spring frost in Imperial, CA?
Plan for the last spring frost in Imperial around January 14 (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 Imperial, CA?
The first fall frost in Imperial typically arrives around December 24 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is Imperial in?
Imperial is in USDA hardiness zone 10a. In zone 10a, winters are mild — many tender perennials overwinter here.
How long is the growing season in Imperial?
There are roughly 344 frost-free days in Imperial (a long growing season), running from the average last frost around January 14 to the first fall frost near December 24.
When should I plant tomatoes in Imperial?
In Imperial, start tomato seeds indoors around November 19–December 3, then transplant seedlings outdoors around January 21 once the danger of frost has passed.
Never miss a window in Imperial
An email when it’s time to start seeds, transplant, and sow — timed to Imperial’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reachFrost dates recorded at IMPERIAL CO AP, 1 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 Imperial, CA — Frost Dates & Zone 10a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USW00003144. Retrieved from https://blissgarden.com/california/imperial.