Superior, AZ Frost Dates & Growing Season

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

Last spring frost
Jan 18
~50% chance of frost after
First fall frost
Dec 28
~50% chance of frost before
Growing season
344 days
frost-free stretch
USDA zone
≈ 9b
estimated from nearby reference
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost Dec 19 Jan 18 Mar 1
First fall frost Feb 1 Dec 28 Dec 1
Hard freeze (28°F), median last Jan 9 · first Jan 7

Computed from NOAA 1991–2020 climate normals at the SUPERIOR station. "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 Superior

Computed from Superior'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 23 – Dec 7 Jan 25 – Feb 1
🫑 Peppers Nov 9 – Nov 23 Feb 1 – Feb 8
🥬 Lettuce Dec 7 – Dec 21 Dec 21 – Jan 4 Dec 21 – Jan 18
🫛 Peas Dec 7 – Dec 21
🥕 Carrots Dec 28 – Jan 18
🥦 Broccoli Nov 30 – Dec 14 Dec 28 – Jan 11
🥬 Kale Dec 7 – Dec 21 Dec 21 – Jan 4 Dec 21 – Jan 4
🥒 Cucumbers Dec 21 – Dec 28 Jan 25 – Feb 1 Jan 25 – Feb 1
🥒 Zucchini Dec 21 – Dec 28 Jan 25 – Feb 1 Jan 25 – Feb 1
🫘 Green Beans (Bush) Jan 25 – Feb 1
🌽 Sweet Corn Jan 25 – Feb 1
🌿 Basil Dec 7 – Dec 21 Jan 25 – Feb 1 Feb 1 – Feb 8
🧄 Garlic Fall: Nov 16 – Dec 14

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 Superior's dates automatically after a lookup.

Reading the season in Superior

With roughly 344 frost-free days, Superior 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 Dec 28 is late enough that fall planting is a full second season, not an afterthought.

Frequently asked questions

When is the last frost in Superior, AZ?

The average last spring frost in Superior is around Jan 18, 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 Superior, AZ?

The average first fall frost in Superior arrives around Dec 28. 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 Superior?

About 344 frost-free days on average, from Jan 18 to Dec 28. That comfortably fits long-season crops like melons and winter squash, plus spring and fall plantings of cool-season vegetables.

What USDA zone is Superior 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.