Phoenix, AZ Frost Dates & Growing Season

The two dates every Phoenix garden is planned around, plus ready-computed planting windows for the most popular crops.

Last spring frost
Jan 5
~50% chance of frost after
First fall frost
Jan 3
~50% chance of frost before
Growing season
363 days
frost-free stretch
USDA zone
9b
2023 hardiness map
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost Dec 19 Jan 5 Jan 22
First fall frost Jan 21 Jan 3 Dec 18

Computed from NOAA 1991–2020 climate normals at the Phoenix Sky Harbor International Airport station (7 km from central Phoenix). "Safe" means frost past that date happens only about one year in ten. Your exact garden can still run days either way with elevation and terrain — check your own ZIP with the frost date lookup.

Planting windows for Phoenix

Computed from Phoenix's own frost dates. Click any crop for the full zone-9 growing guide — varieties, spacing, fall plantings, and more.

CropStart seeds indoorsTransplantDirect sow
🍅 Tomatoes Nov 10 – Nov 24 Jan 12 – Jan 19
🫑 Peppers Oct 27 – Nov 10 Jan 19 – Jan 26
🥬 Lettuce Nov 24 – Dec 8 Dec 8 – Dec 22 Dec 8 – Jan 5
🫛 Peas Nov 24 – Dec 8
🥕 Carrots Dec 15 – Jan 5
🥦 Broccoli Nov 17 – Dec 1 Dec 15 – Dec 29
🥬 Kale Nov 24 – Dec 8 Dec 8 – Dec 22 Dec 8 – Dec 22
🥒 Cucumbers Dec 8 – Dec 15 Jan 12 – Jan 19 Jan 12 – Jan 19
🥒 Zucchini Dec 8 – Dec 15 Jan 12 – Jan 19 Jan 12 – Jan 19
🫘 Green Beans (Bush) Jan 12 – Jan 19
🌽 Sweet Corn Jan 12 – Jan 19
🌿 Basil Nov 24 – Dec 8 Jan 12 – Jan 19 Jan 19 – Jan 26
🧄 Garlic Fall: Nov 22 – Dec 20

Want this for all 50 crops, or as a printable seed-shelf schedule? Use the planting calendar and the seed starting scheduler — both can use Phoenix's dates automatically after a lookup.

Reading the season in Phoenix

With roughly 363 frost-free days, Phoenix gardens fit long-season crops — melons, winter squash, sweet potatoes — with room left for spring and fall rounds of greens and roots. The first frost around Jan 3 is late enough that fall planting is a full second season, not an afterthought.

Frequently asked questions

When is the last frost in Phoenix, AZ?

The average last spring frost in Phoenix is around Jan 5, based on 1991–2020 climate normals. That's a median — about half of years see a later frost, so tender crops are safest going out a week or two after this date.

When is the first frost in Phoenix, AZ?

The average first fall frost in Phoenix arrives around Jan 3. Crops still in the garden need to mature before then, and frost-tender plants need harvesting or protection as the date approaches.

How long is the growing season in Phoenix?

About 363 frost-free days on average, from Jan 5 to Jan 3. That comfortably fits long-season crops like melons and winter squash, plus spring and fall plantings of cool-season vegetables.

What USDA zone is Phoenix in?

USDA zone 9b on the 2023 Plant Hardiness Zone Map. Note that zones describe winter cold, not frost timing — these frost dates are the numbers to plan plantings around.