Stewart Mtn Dam, AZ Frost Dates & Growing Season

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

Last spring frost
Feb 13
~50% chance of frost after
First fall frost
Dec 5
~50% chance of frost before
Growing season
295 days
frost-free stretch
USDA zone
≈ 9b
estimated from nearby reference
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost Jan 10 Feb 13 Mar 8
First fall frost Dec 26 Dec 5 Nov 18
Hard freeze (28°F), median last Jan 18 · first Dec 19

Computed from NOAA 1991–2020 climate normals at the STEWART MTN DAM 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 Stewart Mtn Dam

Computed from Stewart Mtn Dam'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 Dec 19 – Jan 2 Feb 20 – Feb 27
🫑 Peppers Dec 5 – Dec 19 Feb 27 – Mar 6
🥬 Lettuce Jan 2 – Jan 16 Jan 16 – Jan 30 Jan 16 – Feb 13
🫛 Peas Jan 2 – Jan 16
🥕 Carrots Jan 23 – Feb 13
🥦 Broccoli Dec 26 – Jan 9 Jan 23 – Feb 6
🥬 Kale Jan 2 – Jan 16 Jan 16 – Jan 30 Jan 16 – Jan 30
🥒 Cucumbers Jan 16 – Jan 23 Feb 20 – Feb 27 Feb 20 – Feb 27
🥒 Zucchini Jan 16 – Jan 23 Feb 20 – Feb 27 Feb 20 – Feb 27
🫘 Green Beans (Bush) Feb 20 – Feb 27
🌽 Sweet Corn Feb 20 – Feb 27
🌿 Basil Jan 2 – Jan 16 Feb 20 – Feb 27 Feb 27 – Mar 6
🧄 Garlic Fall: Oct 24 – Nov 21

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 Stewart Mtn Dam's dates automatically after a lookup.

Reading the season in Stewart Mtn Dam

With roughly 295 frost-free days, Stewart Mtn Dam 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 5 is late enough that fall planting is a full second season, not an afterthought.

Frequently asked questions

When is the last frost in Stewart Mtn Dam, AZ?

The average last spring frost in Stewart Mtn Dam is around Feb 13, 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 Stewart Mtn Dam, AZ?

The average first fall frost in Stewart Mtn Dam arrives around Dec 5. 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 Stewart Mtn Dam?

About 295 frost-free days on average, from Feb 13 to Dec 5. That comfortably fits long-season crops like melons and winter squash, plus spring and fall plantings of cool-season vegetables.

What USDA zone is Stewart Mtn Dam 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.