When to plant in Rio Rico, AZ
USDA Zone 8bEverything below — frost dates, hardiness zone, and what to plant when in Rio Rico, Arizona — is derived from the closest NOAA station with complete climate normals.
Zone 8b means many perennials and even some tender shrubs overwinter in Rio Rico, while your frost dates still decide when annuals go out.
Frost probability
NOGALES 6 N · 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 Rio Rico’s own odds, recorded at NOGALES 6 N.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 18 | May 2 | Apr 18 | Oct 10 | Oct 24 | Nov 6 |
| 32°F | May 4 | Apr 16 | Mar 28 | Oct 19 | Nov 2 | Nov 16 |
| 28°F | Apr 15 | Mar 22 | Feb 26 | Oct 29 | Nov 14 | Nov 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 Rio Rico, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 16 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.
Rio Rico planting FAQ
When is the last spring frost in Rio Rico, AZ?
Plan for the last spring frost in Rio Rico around April 16 (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 Rio Rico, AZ?
In Rio Rico, the first 32°F freeze of fall lands around November 2 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is Rio Rico in?
Rio Rico is in USDA hardiness zone 8b. In zone 8b, winters are mild — many tender perennials overwinter here.
How long is the growing season in Rio Rico?
There are roughly 200 frost-free days in Rio Rico (a moderate growing season), running from the average last frost around April 16 to the first fall frost near November 2.
When should I plant tomatoes in Rio Rico?
In Rio Rico, start tomato seeds indoors around February 19–March 5, then transplant seedlings outdoors around April 23 once the danger of frost has passed.
Never miss a window in Rio Rico
An email when it’s time to start seeds, transplant, and sow — timed to Rio Rico’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Nogales · 16 km
- Green Valley · 38 km
- Sahuarita · 48 km
- Sierra Vista · 64 km
- Vail · 65 km
- Valencia West · 72 km
- Drexel Heights · 72 km
- Sierra Vista Southeast · 73 km
Frost dates recorded at NOGALES 6 N, 5 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 Rio Rico, AZ — Frost Dates & Zone 8b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00025924. Retrieved from https://blissgarden.com/arizona/rio-rico.