When to plant in San Tan Valley, AZ
USDA Zone 9bHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for San Tan Valley, Arizona — all computed from San Tan Valley's nearest NOAA weather station.
San Tan Valley enjoys a long ~313-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 San Tan Valley can grow subtropical perennials, and the short (or absent) frost period barely limits the annual calendar.
Frost probability
CHANDLER HEIGHTS · 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 San Tan Valley’s own odds, recorded at CHANDLER HEIGHTS.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Mar 11 | Feb 21 | Jan 29 | Nov 12 | Nov 28 | Dec 14 |
| 32°F | Feb 27 | Feb 1 | Jan 2 | Nov 23 | Dec 11 | Jan 1 |
| 28°F | Feb 11 | Jan 8 | Dec 15 | Dec 4 | Dec 26 | Jan 29 |
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 San Tan Valley, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 23 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.
San Tan Valley planting FAQ
When is the last spring frost in San Tan Valley, AZ?
San Tan Valley's average last spring frost falls near February 1 — the 50% mark at 32°F in the 1991–2020 normals. Hold tender transplants until the risk has passed, then plant out.
When is the first fall frost in San Tan Valley, AZ?
The first fall frost in San Tan Valley typically arrives around December 11 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is San Tan Valley in?
San Tan Valley is in USDA hardiness zone 9b. In zone 9b, winters are mild — many tender perennials overwinter here.
How long is the growing season in San Tan Valley?
There are roughly 313 frost-free days in San Tan Valley (a long growing season), running from the average last frost around February 1 to the first fall frost near December 11.
When should I plant tomatoes in San Tan Valley?
In San Tan Valley, start tomato seeds indoors around December 7–December 21, then transplant seedlings outdoors around February 8 once the danger of frost has passed.
Never miss a window in San Tan Valley
An email when it’s time to start seeds, transplant, and sow — timed to San Tan Valley’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Queen Creek · 8 km
- Florence · 18 km
- Gilbert · 22 km
- Apache Junction · 23 km
- Gold Canyon · 24 km
- Coolidge · 27 km
- Mesa · 28 km
- Sun Lakes · 29 km
Frost dates recorded at CHANDLER HEIGHTS, 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 San Tan Valley, AZ — Frost Dates & Zone 9b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00021514. Retrieved from https://blissgarden.com/arizona/san-tan-valley.