Cool-Season Vegetable

When to Plant Spinach in Arizona

Fast from seed to salad. Spinach bolts in heat, so plant early in spring and again in fall.

The Short Answer

Spinach are cold-tolerant and do well in Arizona's varied climate. You can direct sow 6 weeks before your last frost — that's as early as May 15 - Jun 5 in Northern Arizona (Flagstaff). Arizona gardeners can also plant a fall crop. Alkaline, mineral-rich desert soils. Low organic matter. Heavy amendment with compost essential....

Arizona Frost Dates

Your planting dates depend on which part of Arizona you're in. Here are the frost date ranges by region:

Region Zones Last Frost (Spring) First Frost (Fall)
Northern Arizona (Flagstaff) 4b, 5a, 5b, 6a May 15 - Jun 5 Sep 15 - Oct 10
Central Arizona (Phoenix) 9a, 9b, 10a Jan 15 - Feb 10 Dec 1 - Dec 20
Southern Arizona (Tucson) 8b, 9a, 9b Feb 1 - Feb 25 Nov 20 - Dec 15

Spinach Planting Schedule for Arizona

Northern Arizona (Flagstaff) (Zones 4b, 5a, 5b, 6a)

Average last frost: May 15 - Jun 5 · Average first frost: Sep 15 - Oct 10

Direct Sow
6 wks before frost
Fall Planting
6 wks before first frost

Central Arizona (Phoenix) (Zones 9a, 9b, 10a)

Average last frost: Jan 15 - Feb 10 · Average first frost: Dec 1 - Dec 20

Direct Sow
6 wks before frost
Fall Planting
6 wks before first frost

Southern Arizona (Tucson) (Zones 8b, 9a, 9b)

Average last frost: Feb 1 - Feb 25 · Average first frost: Nov 20 - Dec 15

Direct Sow
6 wks before frost
Fall Planting
6 wks before first frost

Growing Spinach in Arizona

Spinach in Arizona's Climate

Spinach requires the narrowest window of any green in subtropical zones. Sow from November through January only. Once temperatures exceed 70°F consistently, spinach bolts within days. Vietnamese cilantro and Malabar spinach are warm-weather alternatives that fill the same role in the kitchen.

Soil Considerations for Arizona

Alkaline, mineral-rich desert soils. Low organic matter. Heavy amendment with compost essential. Caliche layers may need to be broken.

Arizona Climate & Growing Season

Extreme heat in summer lowlands. Two planting seasons in Phoenix — spring and fall (summer is too hot). High elevation has traditional cold-climate seasons. Spinach can handle frost well, which is an advantage in Arizona's climate. You can push planting dates earlier in spring and extend into fall.

Growing season length varies across Arizona: Northern Arizona (Flagstaff) (4b, 5a, 5b, 6a) has a last frost around May 15 - Jun 5, while Southern Arizona (Tucson) (8b, 9a, 9b) sees frost end around Feb 1 - Feb 25. This difference matters for spinach — adjust your planting dates to match your specific region.

Growing Tips

Direct sow as soon as soil can be worked in spring. For fall, plant 6-8 weeks before first frost.

Companion Planting

Plant spinach alongside these companions for better growth:

Strawberries Peas Radishes

The Bottom Line

Spinach can be grown successfully across Arizona, but your exact planting dates depend on which region you're in. Northern Arizona (Flagstaff) gardeners should plan around a May 15 - Jun 5 last frost, while those in Southern Arizona (Tucson) can typically plant earlier. For exact dates based on your zip code, use our free planting date finder.

Related Guides

Spinach Growing Guide National planting guide with all states Arizona Planting Calendar All plants for Arizona Spinach in Alabama Alabama planting dates Spinach in Alaska Alaska planting dates Spinach in Arkansas Arkansas planting dates
Note: All dates are based on NOAA 30-year Climate Normals and represent historical averages, not predictions for any specific year. Always check your local weather forecast before planting frost-sensitive crops. Learn about our data sources.

Last reviewed: March 29, 2026

Ready to Start Planting?

Enter your zip code and pick your plant. We'll tell you exactly when to plant, start seeds, and harvest — based on where you live.

Find Your Planting Dates