When to plant in Monrovia, CA
USDA Zone 10aEverything below — frost dates, hardiness zone, and what to plant when in Monrovia, California — is derived from the closest NOAA station with complete climate normals.
In zone 10a, frost is a minor factor for Monrovia — most perennials thrive, and annual vegetables can go out early and stay late.
Frost probability
MT WILSON CBS · 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 Monrovia’s own odds, recorded at MT WILSON CBS.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Jun 4 | May 15 | Apr 21 | Oct 3 | Oct 30 | Nov 19 |
| 32°F | May 27 | Apr 28 | Mar 31 | Oct 18 | Nov 15 | Dec 9 |
| 28°F | May 10 | Apr 8 | Feb 28 | Nov 5 | Dec 4 | Dec 29 |
Download this table as CSV ↓ — every threshold and probability, plus this city’s planting-window dates.
What to plant now
TODAY · JULY 19Full-year planting calendar
Each bar is the exact window to take a planting action in Monrovia, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 15 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.
Monrovia planting FAQ
When is the last spring frost in Monrovia, CA?
Plan for the last spring frost in Monrovia around April 28 (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 Monrovia, CA?
Expect Monrovia's first fall frost near November 15 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Monrovia in?
Monrovia is in USDA hardiness zone 10a. In zone 10a, winters are mild — many tender perennials overwinter here.
How long is the growing season in Monrovia?
Monrovia has about 201 frost-free days — a moderate growing season — between the average last spring frost (April 28) and first fall frost (November 15).
When should I plant tomatoes in Monrovia?
For Monrovia, sow tomatoes indoors about March 3–March 17 and move the seedlings out around May 5, after the last spring frost.
Never miss a window in Monrovia
An email when it’s time to start seeds, transplant, and sow — timed to Monrovia’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Duarte · 3 km
- Arcadia · 6 km
- Sierra Madre · 6 km
- Azusa · 7 km
- Baldwin Park · 9 km
- Vincent · 9 km
- Temple City · 10 km
- East San Gabriel · 10 km
Frost dates recorded at MT WILSON CBS, 11 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 Monrovia, CA — Frost Dates & Zone 10a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00046006. Retrieved from https://blissgarden.com/california/monrovia.