Diamond M Ranch, AZ Frost Dates & Growing Season

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

Last spring frost
May 17
~50% chance of frost after
First fall frost
Oct 10
~50% chance of frost before
Growing season
146 days
frost-free stretch
USDA zone
≈ 6a
estimated from nearby reference
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost May 1 May 17 Jun 4
First fall frost Oct 26 Oct 10 Sep 28
Hard freeze (28°F), median last Apr 30 · first Oct 23

Computed from NOAA 1991–2020 climate normals at the DIAMOND M RCH 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 Diamond M Ranch

Computed from Diamond M Ranch's own frost dates. Click any crop for the full zone-6 growing guide — varieties, spacing, fall plantings, and more.

CropStart seeds indoorsTransplantDirect sow
🍅 Tomatoes Mar 22 – Apr 5 May 24 – May 31
🫑 Peppers Mar 8 – Mar 22 May 31 – Jun 7
🥬 Lettuce Apr 5 – Apr 19 Apr 19 – May 3 Apr 19 – May 17
🫛 Peas Apr 5 – Apr 19
🥕 Carrots Apr 26 – May 17
🥦 Broccoli Mar 29 – Apr 12 Apr 26 – May 10
🥬 Kale Apr 5 – Apr 19 Apr 19 – May 3 Apr 19 – May 3
🥒 Cucumbers Apr 19 – Apr 26 May 24 – May 31 May 24 – May 31
🥒 Zucchini Apr 19 – Apr 26 May 24 – May 31 May 24 – May 31
🫘 Green Beans (Bush) May 24 – May 31
🌽 Sweet Corn May 24 – May 31
🌿 Basil Apr 5 – Apr 19 May 24 – May 31 May 31 – Jun 7
🧄 Garlic Fall: Aug 29 – Sep 26

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 Diamond M Ranch's dates automatically after a lookup.

Reading the season in Diamond M Ranch

At about 146 frost-free days, Diamond M Ranch rewards efficiency: start warm-season crops indoors, favor short-season varieties, and lean on cold-tolerant crops — peas, kale, roots — that shrug off the shoulder-season frosts on either end.

Frequently asked questions

When is the last frost in Diamond M Ranch, AZ?

The average last spring frost in Diamond M Ranch is around May 17, 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 Diamond M Ranch, AZ?

The average first fall frost in Diamond M Ranch arrives around Oct 10. 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 Diamond M Ranch?

About 146 frost-free days on average, from May 17 to Oct 10. That favors short-season varieties and transplants for warm-season crops, with cool-season vegetables doing the heavy lifting in spring and fall.

What USDA zone is Diamond M Ranch in?

USDA zone 6a 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.