When to plant in Tucson Mountains, AZ
USDA Zone 9bEverything below — frost dates, hardiness zone, and what to plant when in Tucson Mountains, Arizona — is derived from the closest NOAA station with complete climate normals.
Tucson Mountains enjoys a long ~294-day frost-free season — you can succession-sow, fit in a second crop, and grow long-season heat-lovers with room to spare. Zone 9b is warm enough that Tucson Mountains can grow subtropical perennials, and the short (or absent) frost period barely limits the annual calendar.
The average last spring frost in Tucson Mountains is now 10 days earlier than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
TUCSON U OF A #1 · 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 Tucson Mountains’s own odds, recorded at TUCSON U OF A #1.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Mar 30 | Mar 6 | Feb 12 | Nov 4 | Nov 22 | Dec 6 |
| 32°F | Mar 7 | Feb 11 | Jan 16 | Nov 16 | Dec 2 | Dec 20 |
| 28°F | Feb 17 | Jan 18 | Dec 21 | Nov 29 | Dec 15 | Jan 17 |
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 Tucson Mountains, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 11 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.
Tucson Mountains planting FAQ
When is the last spring frost in Tucson Mountains, AZ?
Plan for the last spring frost in Tucson Mountains around February 11 (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 Tucson Mountains, AZ?
The first fall frost in Tucson Mountains typically arrives around December 2 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is Tucson Mountains in?
Tucson Mountains is in USDA hardiness zone 9b. In zone 9b, winters are mild — many tender perennials overwinter here.
How long is the growing season in Tucson Mountains?
There are roughly 294 frost-free days in Tucson Mountains (a long growing season), running from the average last frost around February 11 to the first fall frost near December 2.
When should I plant tomatoes in Tucson Mountains?
In Tucson Mountains, start tomato seeds indoors around December 17–December 31, then transplant seedlings outdoors around February 18 once the danger of frost has passed.
Never miss a window in Tucson Mountains
An email when it’s time to start seeds, transplant, and sow — timed to Tucson Mountains’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Flowing Wells · 6 km
- Casas Adobes · 9 km
- Tucson Estates · 12 km
- Drexel Heights · 15 km
- Valencia West · 17 km
- Oro Valley · 18 km
- Catalina Foothills · 18 km
- Marana · 21 km
Frost dates recorded at TUCSON U OF A #1, 7 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 Tucson Mountains, AZ — Frost Dates & Zone 9b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00028817. Retrieved from https://blissgarden.com/arizona/tucson-mountains.