Growing Sweet Potatoes in the Pacific Northwest

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Last year I took on a challenge: growing sweet potatoes in the Pacific Northwest, known for being cool and rainy. I’m actually located right near Portland, OR, but across the river in wetter Washington State.

People hinted to me that it wouldn’t work.

Might as well find out, right? I started with organic sweet potatoes form Costco. Nothing special. Thinking back on it now, I probably should have picked a short-season variety for better success. Territorial Seed has a few varieties that work better in cooler, shorter climates.

sweet-potato

Starting Sweet Potato Slips

Somewhere I had read that you should start your sweet potato slips around April 18th. However, if I were to do it again, I would probably start growing my slips much earlier – maybe even January.

I began by cutting three sweet potatoes in half, and placing them cut side down into bread pans. I then filled the pans with water 1/2 inch deep, and set them in the warmest place in the house – the kitchen window. Then I began to wait. And wait. And wait. See the video below for details on starting your own slips.

It took a very long time, about 4 weeks to be precise, but finally the potatoes began to sprout. Once they started, they took off! When a slip was about 8 inches tall, I would break it off and place it in a glass of water where it would grow roots. Meanwhile, the sweet potato would grow more slips!

About a week after placing the slips in the glass of water, they would have some well established roots. At this point, I planted each slip into a 4″ pot of soil. This step really depends on the weather – if it is June and already quite warm, you can actually plant the rooted slips straight into the garden.

I planted my potted sweet potatoes (and some new slips with roots) into the garden on June 7th. I made sure my garden bed was in full sun, and tried to slant the bed slightly south for more direct sun-exposure. I didn’t quite have enough slips to fill my 4′ x 8′ garden bed, so I continued to grow more slips and plant them as they were ready.

When to Harvest Sweet Potatoes

The sweet potatoes grew all summer long, with minimal maintenance required. I did weed a few times, and watered regularly. I had read online that sweet potatoes may be left in the ground until the first frost, but I couldn’t quite wait that long. I harvested mine on October 26th. I was happy to find quite a few medium-large sweet potatoes, and quite a few smaller ones! However, some sort of critter (maybe rats) had harvested more than half of my plants before I did. This was disappointing, but overall it was a successful year growing sweet potatoes! Now I know that it IS possible to grow sweet potatoes in the Pacific Northwest.

Watch the video below to see our harvest and other tips on growing your own sweet potatoes.

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5 thoughts on “Growing Sweet Potatoes in the Pacific Northwest

  1. I am surprised to see that maybe I can grow sweet potatoes because I love them in just about everything. I live in Aberdeen on the Wash. coast. I think I will give this a try. Where did you find your seed potatoes?

  2. Hello Matthew
    I was all set to try this last year when the supplies for my slips did not come through…Southern Seed Supply…though I contacted them three times about the issue and they kept telling that we were on a later ship date for Washington. I already know that I have an issue in my beds with R_A_T_S, but also have the crows (wait on the fence to pull up new brassica starts), possums and raccoons to contend with. I think that the black mulch that I already put in place would not only help with the critters but would make your beds warmer perhaps. I really appreciated your article and will absorb all your helpful advice. Merci’. Have you tried watermelon yet?

    • Susan, I did try watermelon a couple times. Had good success with “Moon and Stars” variety one year. The hardest part is knowing when they are ripe, and also keeping the slugs away from them. Good to hear from you!

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