When to plant sweet potatoes in Oregon and Washington

In Portland: Plant sweet potato slips May 25 – Jun 15. In Bend: Jun 16 – Jul 7. Find your city below.

Difficulty: Tricky here
Sun: Full sun; the hottest spot you have
Spacing: 12 to 18 inches apart in a raised row
Planting depth: Bury slips up to the top few leaves
Frost: Killed by frost
First harvest: About 100 days after planting

Easy in hot eastern valleys, a gamble west of the Cascades. Wait for warm soil, use black plastic mulch and choose a short-season variety like Georgia Jet.

Sweet potatoes planting dates

City	Plant in the garden
Portland, OR	May 25 – Jun 15
Seattle and Tacoma, WA	May 25 – Jun 15
Eugene, OR	May 25 – Jun 15
Spokane, WA	May 30 – Jun 20
Bend and Redmond, OR	Jun 16 – Jul 7
Tri-Cities (Pasco, Kennewick, Richland), WA	May 10–31

Find your town

Portland area, OR 6 towns

City	Plant in the garden
Gresham, OR	May 25 – Jun 15
Hillsboro and Beaverton, OR	May 25 – Jun 15
Oregon City and West Linn, OR	May 25 – Jun 15
Portland, OR	May 25 – Jun 15
St. Helens and Scappoose, OR	May 25 – Jun 15
Wilsonville and Canby, OR	May 25 – Jun 15

Willamette Valley, OR 5 towns

City	Plant in the garden
Corvallis and Albany, OR	May 25 – Jun 15
Cottage Grove, OR	May 25 – Jun 15
Eugene, OR	May 25 – Jun 15
McMinnville and Newberg, OR	May 25 – Jun 15
Salem, OR	May 25 – Jun 15

Southern Oregon, OR 4 towns

City	Plant in the garden
Ashland and Talent, OR	May 25 – Jun 15
Grants Pass, OR	May 25 – Jun 15
Medford, OR	May 25 – Jun 15
Roseburg, OR	May 25 – Jun 15

Oregon Coast, OR 5 towns

City	Plant in the garden
Astoria, OR	Jun 1–22
Brookings and Gold Beach, OR	Jun 1–22
Coos Bay and North Bend, OR	Jun 1–22
Newport and Lincoln City, OR	Jun 1–22
Tillamook, OR	Jun 1–22

Central Oregon and the high desert, OR 6 towns

City	Plant in the garden
Bend and Redmond, OR	Jun 16 – Jul 7
Burns, OR	Jun 18 – Jul 9
Klamath Falls, OR	Jun 16 – Jul 7
Lakeview, OR	Jun 11 – Jul 2
Madras, OR	Jun 5–26
Prineville, OR	Jun 8–29

Columbia Gorge and eastern Oregon, OR 9 towns

City	Plant in the garden
Baker City, OR	Jun 5–26
Enterprise and Joseph, OR	Jun 5–26
Hermiston, OR	May 10–31
Hood River, OR	May 10–31
John Day, OR	Jun 5–26
La Grande, OR	May 30 – Jun 20
Ontario, OR	May 10–31
Pendleton, OR	May 10–31
The Dalles, OR	May 10–31

Seattle and Puget Sound, WA 6 towns

City	Plant in the garden
Bremerton and Port Orchard, WA	May 25 – Jun 15
Everett, WA	May 25 – Jun 15
Kent, Renton and Auburn, WA	May 25 – Jun 15
Olympia, WA	May 25 – Jun 15
Seattle and Tacoma, WA	May 25 – Jun 15
Shelton, WA	May 25 – Jun 15

North Sound and the islands, WA 5 towns

City	Plant in the garden
Anacortes, WA	May 25 – Jun 15
Bellingham, WA	May 25 – Jun 15
Friday Harbor and the San Juans, WA	May 25 – Jun 15
Mount Vernon and Burlington, WA	May 25 – Jun 15
Oak Harbor and Whidbey Island, WA	May 25 – Jun 15

Olympic Peninsula and coast, WA 6 towns

City	Plant in the garden
Aberdeen and Hoquiam, WA	Jun 1–22
Forks, WA	Jun 1–22
Long Beach and Ilwaco, WA	Jun 1–22
Port Angeles, WA	May 25 – Jun 15
Port Townsend, WA	May 25 – Jun 15
Sequim, WA	May 25 – Jun 15

Southwest Washington, WA 3 towns

City	Plant in the garden
Centralia and Chehalis, WA	May 25 – Jun 15
Longview and Kelso, WA	May 25 – Jun 15
Vancouver, WA	May 25 – Jun 15

Wenatchee and the Okanogan, WA 5 towns

City	Plant in the garden
Chelan, WA	May 10–31
Leavenworth, WA	May 30 – Jun 20
Omak and Okanogan, WA	May 30 – Jun 20
Wenatchee, WA	May 10–31
Winthrop and Twisp, WA	May 30 – Jun 20

Yakima Valley and Columbia Basin, WA 8 towns

City	Plant in the garden
Ellensburg, WA	May 30 – Jun 20
Ephrata and Quincy, WA	May 10–31
Goldendale, WA	May 30 – Jun 20
Moses Lake, WA	May 10–31
Sunnyside, Grandview and Prosser, WA	May 10–31
Tri-Cities (Pasco, Kennewick, Richland), WA	May 10–31
Walla Walla, WA	May 10–31
Yakima, WA	May 15 – Jun 5

Spokane and eastern Washington, WA 3 towns

City	Plant in the garden
Colville, WA	May 30 – Jun 20
Pullman, WA	May 30 – Jun 20
Spokane, WA	May 30 – Jun 20

How to grow sweet potatoes

Pick a sunny spot with soil that drains well, and mix in an inch or two of compost.
Plant sweet potato slips on your city's dates, 12 to 18 inches apart in a raised row. Bury slips up to the top few leaves.
Water well for the first two weeks, then only in dry spells: too much water and fertilizer grow vines instead of roots. Black plastic mulch keeps the soil warm all summer.
Harvest: Dig before soil temperatures drop below about 55°F in early fall, and before frost. Cure the roots somewhere warm and humid for a week or two, then store them at room temperature, never in the fridge.

Popular sweet potatoes varieties

Widely sold picks that do well somewhere in Oregon or Washington. The tag says which side of the mountains suits each one best.

Georgia Jet

Red skin, orange flesh · 90 days

One of the fastest sweet potatoes, producing big, moist orange roots in a short, cool season. The best bet for west-side gardens.

Both sides

Covington

Rose skin, orange flesh · 100 days

Smooth, uniform roots with sweet orange flesh that bakes beautifully. It yields well in hot summers and stores for months after curing.

East side

Beauregard

Red-purple skin, orange flesh · 100 days

The most widely grown sweet potato in the U.S., with heavy yields of sweet, moist roots. Best where summers are reliably hot.

East side

Murasaki

Purple skin, white flesh · 105 days

A Japanese-type sweet potato with purple skin and dry, nutty, chestnut-sweet white flesh. It needs a warm, long summer to size up.

East side

Key numbers

Above 65°FSoil to plant
90–120Days to harvest
1–2 weeks at 80–85°FCuring
Cool summersBiggest risk

Growing notes

What makes the difference in Northwest gardens, in plain language.

Can you grow them here?

Sweet potatoes are a tropical crop, and they grow roots only when soil and nights are warm. The hot valleys east of the Cascades grow good crops without much fuss. West of the Cascades and on the coast, harvests are smaller and less certain, but a short-season variety in the warmest spot you have, on black plastic, often gives a worthwhile crop in a warm summer.

Slips and planting

Sweet potatoes are grown from slips, rooted shoots sprouted from a stored root. Buy them from a nursery or mail-order supplier in spring, or sprout your own from a store-bought root about two months ahead. Plant them deep in loose, raised rows once the soil is truly warm, usually a week or two after tomato planting. Water well for the first two weeks, then water less; too much water and nitrogen give you lush vines and small roots.

Harvest, curing and storage

Dig carefully with a fork before the soil cools in early fall, since cold soil damages the roots. Freshly dug sweet potatoes are starchy and bland. Curing them somewhere warm and humid (around 80 to 85°F) for one to two weeks heals skin wounds and turns starch to sugar. Store them at about 55 to 60°F. The fridge gives them a hard core and an off taste.

Common questions about growing sweet potatoes

Can I grow sweet potatoes in Portland or Seattle?

Yes, in a warm summer with the right variety. Use a short-season type like Georgia Jet, black plastic mulch and your sunniest spot, and expect a smaller crop than east of the Cascades.

Can I plant a sweet potato from the store?

Not directly. Sprout it in water or damp soil to grow slips, then plant the rooted slips. Store roots are sometimes treated to stop sprouting, so organic ones work best.

Why are my sweet potatoes not sweet?

They need curing. Keep them warm and humid for a week or two, then wait a few more weeks in storage; the flavor keeps improving.

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