Phoenix, AZ Frost Dates
Average frost dates, USDA hardiness zone, and growing season length for Phoenix, Arizona.
Gardening in Phoenix
Phoenix gardening is an act of joyful defiance against the desert. With irrigation, timing, and shade cloth, the Valley of the Sun grows spectacular food in conditions that seem impossible. Your winter garden is the envy of the nation — fresh tomatoes in December while the rest of the country eats grocery store pink things.
Think of Phoenix gardening as two seasons: the glorious cool season (October through April) when everything grows like a dream, and the brutal hot season (May through September) when only the toughest desert-adapted plants survive. The 110°F days aren't a metaphor — they're a daily reality that melts lesser plants. Desert gardeners learn to work with the heat, not against it.
Suns fans know about running hot — your garden does too. The Valley's citrus heritage goes back generations, and many Phoenix yards still have productive grapefruit and orange trees that predate the subdivisions around them. A backyard citrus tree is practically a Phoenix birthright.
What This Means for Phoenix Gardeners
The average last spring frost in Phoenix is around February 5, and the average first fall frost arrives around December 10. That gives you approximately 308 frost-free days to work with.
308 days is a long, productive season that supports two full rounds of warm-season crops plus continuous cool-season production through your mild winter. Most frost-sensitive crops can be transplanted by February 5, giving them months to produce before fall. Your winter garden is the real advantage — growing fresh vegetables in December and January while northern gardeners browse seed catalogs.
These dates are based on NOAA 30-year Climate Normal data for the Phoenix area. Your actual frost dates could shift 2-3 weeks in either direction in any given year. Learn more about our data sources.
What to Grow in Phoenix
With 308 frost-free days, Phoenix can grow nearly anything — including tropical and subtropical plants that most of the country can only dream about. Your prime vegetable season runs from fall through spring; summer is for heat-lovers like okra, sweet potatoes, and peppers. Recommended starting points: cherry tomatoes, jalapeños, okra, sweet potatoes, basil, collard greens, tomatillos, and lemongrass.
See the full Arizona planting guide for all 40 plants: Arizona Planting Calendar. Or enter your zip code for exact planting dates personalized to Phoenix.
More About Zone 9B
Phoenix is in USDA Hardiness Zone 9B, which means average annual extreme minimum temperatures between 25°F to 30°F. View the full Zone 9B planting guide.
See the complete planting calendar for Arizona: Arizona Planting Calendar.
Other Cities in Arizona
Frequently Asked Questions
These dates are based on NOAA's 30-year Climate Normal data for the Phoenix area. They represent historical averages, not predictions. In any given year, the actual last frost could be 2-3 weeks earlier or later. Microclimates within Phoenix (urban heat islands, hilltops, low-lying valleys) can also shift your local frost dates by a week or more.
You can plant cool-season crops (lettuce, kale, broccoli) from December 10 through February 5 — your cool season is your primary vegetable season. Warm-season crops like tomatoes and peppers go out in early spring. Tropical plants grow year-round. Enter your zip code for exact dates for every plant.