Arizona · zones 5b–10a
When to plant potatoes in Arizona.
Sow between Dec 29 to Jan 31 in a typical year, keyed to Arizona's median last frost around Feb 5. A second, fall sowing fits Jul 28 to Aug 10. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Potatoes dates for a typical Arizona season.
Direct sow
Dec 29 to Jan 31
Keyed to the ~Feb 5 last frost. Sow 4" deep, 12" apart.
Fall round
Jul 28 to Aug 10
Counted back from the ~Nov 15 first frost.
Harvest
~90 days later
~3 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.
Arizona growing notes
Potatoes in the low desert grow through winter.
Winter is the growing season, not spring
In most of the country potatoes are a spring-into-summer crop. In Arizona's low desert, that calendar flips: summer soil temperatures climb well past what a seed potato can tolerate, so the crop goes in as the worst heat breaks and grows through the mild winter months instead, finishing and coming out of the ground before summer heat returns and shuts tuber formation down. Treat the desert's winter, not its summer, as prime potato weather.
Kennebec is the standard low-desert choice because it tolerates heat stress at either end of that window better than thinner-skinned varieties, and it bulks up reliably even with the shorter growing window the desert calendar allows compared with a cooler-summer state. Red La Soda is a solid second choice where a waxier potato is wanted for the table. Cut seed potatoes into pieces with at least 1 or 2 eyes each and set them somewhere warm and airy until the cut face dries to a leathery seal before planting, since a fresh cut going straight into warm desert soil rots more often than one given time to seal over first.
Hilling through caliche
Low desert soil often carries a caliche layer, a hardpan of calcium carbonate that can sit just over a foot down, and potatoes forming tubers against that hard barrier come out flattened and misshapen instead of round. Break up the planting trench to at least 14 inches deep before seed potatoes go in, deeper than the crop needs almost anywhere else, so the developing tubers have room to expand downward instead of pushing sideways against hardpan.
Hill soil up around the stems every 2 to 3 weeks as they grow, covering to within a few inches of the top leaves each time. Desert sun is intense enough that any tuber left exposed near the surface turns green and bitter within a day or two, faster than in a milder climate, so hilling generously matters more here than the amount of soil moved would suggest.
Racing the heat and reading the monsoon risk
Colorado potato beetle is the real threat to a low-desert potato patch as the season turns toward its spring finish: as days warm past the mid-80s, beetle populations build fast, and vines already stressed by rising temperatures and drying soil have less left to fight them off. Late blight needs weather the desert almost never delivers, cool days paired with sustained heavy humidity, and the fungus stops spreading once afternoons top the mid-90s, so foliage collapsing in desert heat points to early blight or plain water stress instead. Scout weekly once daytime highs pass 80 and hand-pick orange egg clusters from leaf undersides before they hatch; a few minutes a week beats a beetle population that has already established.
Harvest as soon as the vines yellow and die back, rather than waiting, because tubers left in warming soil once foliage is gone continue to lose quality fast in desert heat. If harvest timing runs into the first monsoon storms in July, dig on a dry day if at all possible; tubers pulled from waterlogged, storm-soaked soil bruise and rot in storage far faster than ones lifted from dry ground.
In Arizona: watch for
The pests that find potatoes here.
With about 283 frost-free days, potato spends longer in the ground here than in most of the country, which widens the window in which colorado potato beetle can find it. Scout weekly from midseason and act on the first signs.
Striped beetles and orange grubs eating the leaves.
Organic fix: Handpick adults, crush the orange egg clusters, dust with diatomaceous earth.
Dark greasy blotches after cool, wet spells.
Organic fix: Pull infected plants fast, keep leaves dry, use neem as a preventive.
Common scab
Rough, corky patches on the skin, raised on some tubers and sunk into pits on others.
Organic fix: Keep the bed evenly moist through the weeks right after tubers set, rotate away from potatoes, and pick a scab-resistant variety next time.
Your season math: Arizona gives potatoes about 283 frost-free days, and it needs roughly 90 days to a first harvest. It's a one-planting crop, so time that single sowing well.
Planting potatoes in Arizona: questions
When should I plant potatoes in Arizona?+
In a typical Arizona year, sow potatoes between Dec 29 to Jan 31, keyed to the state's median last frost around Feb 5. There's also a fall window: Jul 28 to Aug 10. 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 potatoes 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.