Do gardeners grow sweet potatoes in our region successfully?

Survey says: yes, with effort, sweet potatoes can be a successful crop.

May 08, 2024

Cliff notes: growers in the Willamette Valley/SW Wasghington have great success growing sweet potatoes, if their growing conditions are right.

I personally have no experience growing sweet potatoes, but I was curious to find out if other gardeners in our region are having success with this crop.

Wikipedia has an extensive article of sweet potatoes, which is interesting to read about their original habitat.

As for growing, here is an article by OSU of one grower in particular in Eugene.

In short, what sweet potatoes need:

-all-day sun
-possibly a heat sink (such as plastic) to keep the soil temperature quite warm to hot
-loose and deep soil for tuber formation
-freely draining soil to keep the tubers from rotting
-a steady supply of moisture
-not too high of nitrogen conditions, or they will produce skinny roots
-finally, they need curing in a warm humid spot for about a week 85-90 degrees with high humidity. Suggestions include putting them in a greenhouse or in a heated room with a bucket of water. See gardener #9 and #26 notes of how they rigged up an alternate curing stations for their sweet potatoes.

Grower anecdotes

For those of you that do have the correct conditions to grow and cure sweet potatoes, here are some anecdotes from other gardeners in our region. These are notes that I took after polling gardener groups on Facebook up and down the Willamette Valley and SW Washington.

FL says: “I add them to containers largely because they look nice. I usually end up with smaller sweet potatoes once the vines die back in the fall, which I am fine with. Growing in crowded containers likely reduces yield but container gardening also lowers the risk of problems with disease (easy to dump soil from one container if there is a problem) so I can relax and start them from grocery store sweet potatoes at a much lower cost than buying seed potatoes or slips. One year I accidentally bought non-edible, ornamental sweet potato slips from a nursery without realizing I had grabbed that kind, so it also removes the chance for that type of mistake. They aren’t at all hard to grow, but I think you’d need pretty optimal conditions to produce large tubers here, since it just isn’t hot for long enough most years.” When I asked if they start from grocery store potatoes, they said: “yep. Often in December without realizing it, if my spouse doesn’t cook all of them for Christmas dinner and doesn’t tell me there is a bag of sweet potatoes in the back of the pantry. When that hasn’t happened, once I get my containers started I just go buy a bunch of different colors at New Seasons. If they have any tiny ones I just plant those. If they just have big ones I start slips on the kitchen window sill and plant them as they are ready.”
MV says: “First time grower spring 2022. In raised beds with cow and horse manure/straw, and yard clippings, the greens were very happy and formed a large mat of healthy vines. Tuber formation was pitiful - each one was thinner than a ball point pen - and about as long.” Does not recall variety.
KH says: “I grew slips from a farm in Georgia, Beauregard was the variety. They took a while to take off, but then took over the whole 3X3 bed and buried themselves super deep, I practically had to empty the bed to get them out. I had quite a few good sized ones, but unfortunately something was munching on them. This year I'm planing in a different bed and in very large grow bags. I actually just ate the last of the potatoes this week. I have Georgia Jet slips coming in the mail soon.”
AR says: “I have grown them the last 4 years. I bought slips one year and have been growing my own ever since but don’t remember the variety. They are a warm weather crop so they need lots of sun and a long, warm growing season. My highest harvest in a garden bed was 50lbs from 17 slips.”
Sun Gold Farm says: “We have grown sweet potatoes here near Forest Grove for at least 15 years. Always a success. We only grow Beauregard and use black plastic mulch with drip. (A black garbage bag will work). They don’t need much water or any special fertilizer. The biggest drawbacks are rodents munching holes in them and curing. Cut the vines to harden skin and cure at room temp. They taste soooo much better than store bought.”
AH says: “I grew sweet potatoes a few years ago as a fun experiment. It was the “red garnet” kind from the grocery store. It started to sprout, so I twisted off the little slips, stuck them in water and they rooted. I potted them up and then kept them inside until summer. I had heard we don’t have a long enough growing season for them, but they flowered (very pretty!) and I harvested a good amount from six plants. I left them in the ground as long as I could, it looks like I harvested these in October (looking back through photos).”

Red Garnet yams started from grocery store potatoes in this Portland-area garden.

SDB says: “Yams (nightshade) grow wild in the parks in Keizer/Salem area. I was told yamhill is called that because yams grow all over (haven’t fact checked that but did see a bunch in the wild spaces of the park). I grew sweet potato (morning glory species) in the dirt floor of my green house to make sure they had enough warm days and they got huge! The greens are a delicious spinach substitute in the warmer season. Really easy to propagate. I haven’t tried to grow them outside proper and have had mixed results with container growing.”
SD says: “I experimented with sweet potatoes last year. Used a large organic Red Garnet from the grocery store to grow my slips. Cut them off the potato when they were 6 inches tall, transferred them into jars of water to grow some roots, and planted the rooted slips in a raised bed with a mix of compost, sand, and soil. The results were mixed. I had some reasonable large sweet potatoes that were great in recipes, but there were so many small ones. It was a fun experiment and I will try it again another year, since I need the bed for other starts. The plants are beautiful and the process is just fun! Next time I will choice a different variety, there are some species from Asian markets that I have read about that do well in the PNW. I also think my soil mix was too rich. So I would adjust that.”
NM says: “I made a curing chamber from a plastic tub, a 1/2 gallon jar of water and a seeding mat. Wrapped it in a blanket and had a hole in the top for venting that I covered with a towel to keep bugs and dirt out. Worked perfectly for my 15# harvest. I grew them in a raised bed, they did well! I tried both purple and orange, got both from Bakers Creek. Saved some of each for slips for the following year as well. Worked well!”
JC says: “We bought three starts from a catalog and they shipped them to us. We got them in March of that year and put them immediately into large 3-gallon pots and started the growing in the greenhouse. Then after the danger of frost in May sometime I transplanted them into the garden with several shovel fulls of compost mixed into the soil. We grew them like potatoes after that with plenty of water and harvested about a 3 gallon bucket of sweet potatoes from them in the fall.”
AK says: “I tried growing red Japanese sweet potatoes in a 4’ kiddie pool a few years back. It was a bit of an experiment as I knew I needed short day (<75 day) plants and these were over 100. It was placed in a full sun location but not a hotspot, per se. I got a few ripe smaller potatoes but most of them were green shoestrings. I have not attempted them again.”
EL says: “I would love to know if anyone has had luck growing them in containers. Mine came out like shoestring fries.”
DM says: “I started with 4 (1 had the white inside and the 3 had orange inside)like this; bought from the grocery store and grew them in a raised bed that was filled with 7 way dirt from Boring Bark. The 3x4 foot bed also had lettuce partnered up. The sun hit the box around 10am and had sun the rest of the day. Ended up with 3 white meat ones the size of 2 golf balls each but the orange meat ones gave me 10 very nice sized ones (baker potato size) and about 10 more of various sizes down to finger size. I saved most of the orange small-tiny for planting this year and only 2 of the white. I have no idea of the name of either kind; just got them from the grocery store. Hands down though; the orange meat seems to be the best choice for both being willing to sprout and grow tubers. There were also lots of long fingers/roots that probably would have given me lots more if I lived lower elevation and longer growing season (1300 ft elevation).”
KH says: “The best way to grow them are in 25 gal black pots... and you need to put them in the sunniest place on your property same with melon... I put down black plastic over the ground so that it gathers even more heat... they like their feet warm.. p.s. I start them in the heated green house”
MK says: “Omg 100% worth it!! Personally I adore them for their edible leaves. They do need a very warm place, so I grow mine in a grow bag where they also get reflective heat from our house, I honestly can't remember why a grow bag & not my garden bed next to it... but probably from the crappy soil lol. I've done a Japanese Purple, I think a Korean white (I can't remember the names, but they're drier), & just ones from the store. Of course just like any potato/garlic, I had the least success from ones from the store. You do have to wait to put your slips out till it gets consistently warm enough, which is a tad difficult because they sell out so quickly. Even then, so worth it. I haven't had any problems w/ pests or disease, but I have killed my fair share of slips by putting them out too early.”
SLH says: I grew them last year...had to start on my kitchen table with the sprouts...getting them to root. Daily rinsing so I set them on our breakfast table so I would remember. Once they were showing good roots and good green growth, removed from the potatoe and placed in their own water....again daily fresh water until good roots. Transferred to soil and placed under lights in the greenhouse until risk of frost. Then potted up on grow bags and again placed in our "tomato house" for the summer. Good harvest of beautiful potatoes by Thanksgiving.”
BCM says: “I use a 25 gallon half barrel. I protect with shade cloth on hot or cold days. I train the vines up poles so they don't set root in ground. At harvest time I dump the barrel onto a tarp and pull out the sweet potatoes. I got 36 last year. Then I put soil back into barrel and take tubers inside a warm dark room with humidity to cure. Then they last all winter. I think they are standard Boregards. Next year I wanna try purple skin white flesh type. Didn't start slips in Feb/March so same ones this year.”
LM says: “We successfully grew them for 3 years. We started with a variety, Beauregard, O’Henry and purple (I think). Our favorite was Beauregard which we grew the next two seasons. We are here in OC (Oregon City) and grow in raised beds (except for recent blueberry bushes added after we lost some trees in the back yard). They did good, at least I think so as it was the first time growing so nothing to compare too. The Beauregard were the largest of the three. The purple (really more red than purple) were very thin, so maybe they didn’t do as good as the others, or maybe that’s just the variety. The raised beds get full sun all day. I don’t feel it was difficult, just was worried about how mild the season would be as they like it hot. Didn’t have any issues with pests that I recall. We had them in the same bed as the Yukon gold taters. We need to get more as I love them and so do the pups! Hope this helps. “
MEW says: “Its fun and easy! Do not treat them like potatoes though! Put them in water half submerged in a cup till you get "Slips" (Sprouts off the top of the potato) then take them slips off when they are a few inches long and put them in water like you are propagating them. Once they have Roots that have roots (Branches off the main roots) you can plant them in the ground of dirt or whatever!
If you just throw them in the ground with out doing the slip method you will get a rotten mess and very few if any potatoes!”
ED says: “We had moderate success growing them in bags. They were small, but tasty. I would say it’s possible in grow bags and raised beds.”
KL says: “we tested them last year at the Organic Fields at Heritage Farm and they did great! I can't off the top of my head tell you which kinds, but most flourished in the raised rows albeit heavy-clay soil covered with wood chips....”
LF says: “I grew them a few years ago in northeast Portland and had a good harvest. I put black plastic bags over the soil to warm it before I planted them and left it in place over the summer to help retain heat. I don't know what variety they were I think I ordered slips from territorial seed”
DW says: “they are tropical relatives of morning glory, so mine were outside summer, inside winter, and outside second summer before harvesting after over a year. helped them get bigger. they are more like a houseplant and don't ever stop growing.”
KE says: “I have grown them last year has a great harvest of purple sweet potatoes.”
Diane Awalt says: “Tried a pot one year; just got skinny little things. In a raised bed last year and did quite well. I used out-of-the- produce-department organic. You do have to start from slips, so not like regular potatoes. Photo of slips to plant this year.”
BG says: “grocery store sweet potatoes will work to make your own slips, but I prefer getting a known variety for one year and make your own slips there after. This way you know the variety matures with in the season for our climate not something that does well in California or Carolina. Sweet Potatoes can be grown easily. I have grown them successfully year after year. Summary: Get short season variety slips (90 days), pick a spot which gets hot in the afternoon, wait to plant them until first week of June, don't let them dry out the first 2-3 weeks after planting (important), harvest them in October before freeze, cure them inside the oven with lights on, and store them in the garage wrapped in a news paper.”
SG says: “I have grown sweet potatoes with some success for about 7 or 8 years. Mother Earth News had a great article about growing them and it worked for me. I started with a few organic ones purchased from the grocery store and made my own slips. I tried buying slips, but they were expensive and many of them died. This is the one crop that I use plastic for. My soil is pretty good and I have a sunny location, but sweet potatoes need heat. I use clear plastic sheeting to cover the bed and make sure it is pulled tight. Then cut out spots to put in your slips. Slips, are easy to grow and root. Don't be impatient to plant. You can even wait into June. Once things heat up they will take off. The thing to know about sweet potatoes is that they have to be cured at a pretty high heat for several days. If not cured well, they will rot pretty quickly.”

Considerations in my garden

After reading the above articles and feedback, I think it will be difficult to find the correct conditions that sweet potatoes require in order to grow well on my site.

In particular: my property goes into shade by around 3pm at the height of summer, 5pm in some areas that I have yet to rescue from invasive weeds. In our climate, this is the hottest part of the day, which would be needed to get the soil temperatures high.

The area that does get sun until 5pm would be difficult to water.

Lastly, I don’t have a good set up for the curing process. If I was able to get the correct conditions otherwise, I would be looking to gardener #26 and #9’s rigs for curing.

I’m a little jealous of all of you that do have correct conditions!

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