Idaho · zones 5b–7b
When to plant potatoes in Idaho.
Sow between Apr 3 to May 6 in a typical year, keyed to Idaho's median last frost around May 11. A second, fall sowing fits Jun 10 to Jun 23. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Potatoes dates for a typical Idaho season.
Direct sow
Apr 3 to May 6
Keyed to the ~May 11 last frost. Sow 4" deep, 12" apart.
Fall round
Jun 10 to Jun 23
Counted back from the ~Sep 28 first frost.
Harvest
~90 days later
~3 lb per plant over ~1 weeks.
Idaho spans more than one climate: Zone 6 is the most common zone, but the state runs 5b to 7b. 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.
Idaho growing notes
Potato is the crop that built Idaho's reputation, resting on cool nights and loose valley ground, conditions a backyard grower can put to direct use once the seed piece is cured and the hilling keeps pace with the vine.
Starting from a cut piece, not a whole potato
A home potato crop almost never starts from a whole potato dropped in the ground. It starts from a seed potato cut into smaller pieces, each needing at least one solid eye. A piece planted the same afternoon it was cut, while the cut face is still wet, sits in cool spring soil as an open wound and rots before it gets a real chance to sprout. Cutting the pieces two or three days ahead and leaving them somewhere cool and shaded to dry and callus over solves this outright. A callused piece goes into the ground sealed instead of raw, often the difference between a piece that sprouts and one that just softens and disappears.
From there the numbers are straightforward: pieces go in about 4 inches deep and roughly 12 inches apart, direct into the ground with no transplant stage. A planting reaches harvest in around 90 days, leaving roughly seven weeks of slack inside the state's 140-day frost-free stretch. The Treasure Valley's earlier-warming soil hands a grower there the widest window to work inside; a high-country garden with a shorter effective season does best treating the earliest safe planting as the one worth taking, rather than counting on that slack to cover a late start.
Hilling twice, and what loose valley ground does for tuber shape
Hilling is the job that never quite finishes once it starts. As the vine grows, soil gets pulled up around the stem in more than one pass over the season, burying it a little deeper each time. That buried stem is where the tubers actually form, and one that pushes up out of the hill and into daylight turns green and bitter. There is no fixing a green potato after the fact; the only real move is tossing it and hilling a little higher on the next pass so the rest of the crop stays covered.
The valley's deep, loose volcanic loam is the other reason Idaho potatoes have the reputation they do: a tuber that expands into soil that gives way easily grows smooth and evenly shaped, while the same tuber pushing against rocky or compacted ground comes up knobby or cracked instead. A quick squeeze test on a handful of bed soil shows which kind is in a bed: soil that crumbles apart easily is loose enough, soil that holds together in a dense clump needs work before the next planting, a full spade deep with stones picked out.
The beetle worth checking by hand, and the blight that moves fast in wet air
Colorado potato beetle is the pest most likely to do real damage in a home-size planting, and usually it is the larvae doing it, not the adult. The adult is easy to spot, yellow and black striped, but the brick-red, humpbacked larvae feeding on leaf undersides are what actually strip a plant to bare stems. This beetle overwinters in the soil itself, so a bed planted in potatoes two years running gives it a head start a rotated bed never provides. Checking leaf undersides every few days from the time plants emerge, and picking off adults and larvae by hand, keeps a small planting ahead of it without spraying anything.
Late blight is the one that moves fastest and matters most once it shows up: dark, water-soaked blotches spreading across leaves within days during a wet, humid stretch, a bigger risk in the northern panhandle's damper air than on the dry valley floor. A plant showing blotches like this needs to come out and go in the trash, not the compost pile, since the disease keeps spreading from infected debris left in the garden. Aphids show up too, usually light enough that a strong spray of water off the leaves handles them without further trouble.
In Idaho: watch for
The pests that find potatoes here.
The short season here, about 140 frost-free days, keeps potato in front of colorado potato beetle only briefly. One early row cover usually carries a planting through the worst of it.
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: Idaho gives potatoes about 140 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 Idaho: questions
When should I plant potatoes in Idaho?+
In a typical Idaho year, sow potatoes between Apr 3 to May 6, keyed to the state's median last frost around May 11. There's also a fall window: Jun 10 to Jun 23. Your exact dates shift with your ZIP code and microclimate.
What USDA zone is Idaho?+
Idaho spans zones 5b–7b, mostly zone 6. 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.