Oregon · zones 6a–9a
When to plant potatoes in Oregon.
Sow between Mar 8 to Apr 10 in a typical year, keyed to Oregon's median last frost around Apr 15. A second, fall sowing fits Jul 7 to Jul 20. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Potatoes dates for a typical Oregon season.
Direct sow
Mar 8 to Apr 10
Keyed to the ~Apr 15 last frost. Sow 4" deep, 12" apart.
Fall round
Jul 7 to Jul 20
Counted back from the ~Oct 25 first frost.
Harvest
~90 days later
~3 lb per plant over ~1 weeks.
Oregon spans more than one climate: Zone 8 is the most common zone, but the state runs 6a to 9a. 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.
Oregon growing notes
Potatoes and tomatoes here can pass the exact same blight back and forth, and a seed potato's real defense starts with hilling and drainage rather than with which side of the Cascades it's planted on.
A seed piece, not a seed, and its two windows
A chunk of potato with at least one eye, a seed piece, starts this crop here, set 4 inches deep and 12 inches apart in the row, deeper than any other direct-planted crop. That depth matters all season: hilling, mounding extra soil against the stem as the plant grows, keeps developing tubers covered, and a tuber that pushes into sunlight turns green and starts producing solanine, which makes that part bitter and unsafe to eat. A green shoulder is a hilling problem, not a disease, and cutting the green part away before cooking fixes the odd one that slips through.
Both a spring and a fall planting fit into this crop's calendar here, short enough at 90 days to leave room for a second attempt. Spring is standard, seed pieces going into soil that has warmed enough to work rather than sit wet and cold. A fall crop uses small potatoes held back from that spring harvest as seed, replanted in mid to late summer to dig before real cold returns; it asks more of the remaining frost-free days, a better bet on the mild, marine side of the state than east of the mountains.
The water mold that blights a tomato does not care which nightshade it lands on
Potato and tomato share late blight here, the same water mold moving between whichever host is nearest once cool, overcast weather leaves foliage damp for hours. Watch for leaf edges and stem tips going dark and collapsing rather than yellowing slowly; it spreads through a stand fast enough to ruin a planting within a week of bad weather. Left unchecked, it moves past the foliage: spores wash down through the soil in rain and infect the tubers, leaving a firm, reddish-brown discoloration under the skin that only shows once cut open.
Hilling matters, though differently than for keeping tubers from greening: a thicker cap of soil gives rain-washed spores farther to travel before reaching a tuber underneath. Destroy rather than compost a blighted plant; that alone won't stop next year's blight, since this water mold can't survive in soil or dead debris, but it does cut the spore pressure hitting healthy plants nearby. The real carryover is living tissue: tubers left in the ground over winter, or held back as seed. The 12-inch spacing this crop gets earns its keep, giving the row air movement that dries foliage faster after rain or dew, and this disease needs standing moisture on a leaf to start.
A beetle that announces itself, and a skin-set test worth trusting over the calendar
Colorado potato beetle is hard to miss, a rounded beetle with bold black and yellow stripes that feeds openly on the leaves along with its dull orange, humpbacked larvae, and a heavy population can strip a plant fast enough to cut the season short. Eggs are the easiest place to get ahead of it, bright orange-yellow clusters on a leaf's underside, and checking there every few days keeps a small population from becoming a stripped plant. Aphids cluster on leaf undersides too, lower stakes than the beetle but worth a look on the same pass.
Skin set, not the calendar, is the real test for when to dig. Ninety days gets a potato to full size, but the skin needs extra time to toughen, since a tuber pulled before the skin toughens bruises and rots faster in storage. Rub a thumb across a test tuber dug from the row's edge: skin that rubs off means wait another week, skin that stays put means the row is ready. A well-grown hill here typically gives back around 3 pounds, spring or fall, though a fall crop on the mild side has better odds of reaching it before the ground turns cold again.
In Oregon: watch for
The pests that find potatoes here.
A middle-length season, about 193 frost-free days, means potato overlaps colorado potato beetle for a stretch each summer. Check plants every week or two and treat early.
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: Oregon gives potatoes about 193 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 Oregon: questions
When should I plant potatoes in Oregon?+
In a typical Oregon year, sow potatoes between Mar 8 to Apr 10, keyed to the state's median last frost around Apr 15. There's also a fall window: Jul 7 to Jul 20. Your exact dates shift with your ZIP code and microclimate.
What USDA zone is Oregon?+
Oregon spans zones 6a–9a, mostly zone 8. 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.