Arizona · zones 5b–10a
When to plant spinach in Arizona.
Sow between Dec 15 to Jan 26 in a typical year, keyed to Arizona's median last frost around Feb 5. A second, fall sowing fits Sep 1 to Oct 20. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Spinach dates for a typical Arizona season.
Direct sow
Dec 15 to Jan 26
Keyed to the ~Feb 5 last frost. Sow 0.5" deep, 3" apart.
Fall round
Sep 1 to Oct 20
Counted back from the ~Nov 15 first frost.
Harvest
~42 days later
~0.25 lb per plant over ~1 weeks.
Arizona spans more than one climate: Zone 9 is the most common zone, but the state runs 5b to 10a. That's why the planner works from your ZIP code's frost dates, not your zone: mountain and coastal gardens in the same state can be three weeks apart.
In Arizona: watch for
The pests that find spinach here.
With about 283 frost-free days, spinach spends longer in the ground here than in most of the country, which widens the window in which leaf miners can find it. Scout weekly from midseason and act on the first signs.
Winding pale tunnels or blotches inside the leaves.
Organic fix: Pick and destroy mined leaves; cover the row.
Cercospora leaf spot
Round spots with gray centers and a red-purple rim, oldest leaves worst.
Organic fix: Space wider so leaves dry fast, clear old debris, and pull pigweed and lambsquarters nearby.
Your season math: Arizona gives spinach about 283 frost-free days, and it needs roughly 42 days to a first harvest. That fits about 35 re-sown rounds across the season, so you can keep it coming instead of picking once.
Planting spinach in Arizona: questions
When should I plant spinach in Arizona?+
In a typical Arizona year, sow spinach between Dec 15 to Jan 26, keyed to the state's median last frost around Feb 5. There's also a fall window: Sep 1 to Oct 20. Your exact dates shift with your ZIP code and microclimate.
What USDA zone is Arizona?+
Arizona spans zones 5b–10a, mostly zone 9. But frost dates, not zones, set planting time. The free planner uses your ZIP code's actual frost dates.
How many spinach plants do I need?+
Depends who you're feeding. The crop page has exact counts per household size, or the free planner does the math for your family in about 60 seconds.