Sweet Potatoes

Growing Sweet Potatoes

My Background

As with the taro, I'm pretty much a new comer to growing sweet potatoes. I started growing them about a year ago. As with the taro, I got my start with a potato given to me by Andy and Joy (they are my gardening heroes!). Andy gave me an Okinawan sweet potato, the kind that are purple on the inside. And so it began...

Note: a sweet potato is not really a potato, but I'm going to call it that anyway.

I started with a single sweet potato. I'm pretty sure that anybody can do this. I took the potato, put it in container of dirt, added water every now and then, but mostly left it alone. Eventually vines started growing out of the potato, so I transplanted it into a small section of a raised bed. The vine grew very, VERY quickly, and before long, it was just pretty darn big, and starting to take over.

Lacking anything resembling patience, within a couple of months I was digging around, checking to see if any little potatoes had been started. Not knowing what I was looking for, at, or how to look for it, I didn't find anything, and was discouraged. But I left it alone for a few months, then me and the Shin-meister (my oldest boy) went out and started digging. And were pretty happy. Within the few square feet dedicated to the sweet potatoes, we probably got about five pounds worth. Nice.

After that I built up a raised bed dedicated to sweet potatoes, and grew out another batch, giving them a bit longer, and in that raised bed, which I started from slips and plant leftovers, we got a pretty good take of purple goodness ;o)

The Problem With Sweet Potatoes In Hawai'i

Nah, just kidding. There's no real problem. The closest thing I had to a problem was finding out accurate information about growing them, information that was applicable to Hawai'i. Most of the information I found, both in print and on the web, was oriented towards the mainland. But sweet potatoes are tropical! Go figure.

Starting Out

You can start with a single sweet potato. Just get one, put it in some dirt, water it, and eventually vines will start to grow out of it. Not a real challenge.

Propagating

Sweet potato can be propagated in a few different ways. One is to just take small sweet potatoes and bury them (just like when starting out). Another way is to grow slips. Take a length of sweet potato vine, and cut it into sections, with a shoot (leaf)/vine combo making up each section. Put the sections in a glass of water, and within a couple of days roots will start coming out of the piece of vine.

I have this theory that if you were having a problem related to leaves, disease, bug infestation, something like that, you could take potatoes to a new place and start over and maybe escape from that problem. If you were having a problem related to the potatoes, you could start slips and plant those in a new place, and escape that problem. That might work. Or maybe you'd just be spreading the problem all over your yard, it ain't rocket science, and I'm no rocket scientist.

Now, let me talk about re-use. After harvesting my first batch of sweet potatoes, I was all set to cut up the old vines and make slips and start all over again in the new raised bed. Then my wife asked me why. Her theory was that the plant had already gone to all that work to make this huge vine/leaf mass, why not just replant it. I didn't have an answer against replanting it, so that's what I did. And as far as I can tell, I haven't had any problems at all, nada, zilch. All I did was take that mass of leaves and vine, throw it on the ground, toss a couple shovel fulls of dirt on top, then walk away.

When To Harvest

This was a confusing part for me. Most of what I read indicated that you'd grow the plants all Summer, and when they died, it was time to harvest. This are apparently mainland U.S. info, because if I understand correctly, the plants there die when Winter comes. So basically you grow them out as long as you can, and once they quit growing (because winter comes...), you dig up the potatoes.

I think in Hawai'i it's reasonable to let them go for about six months. I think much more than that and the potatoes start splitting. I had several that were the size of my forearm and hand combined, and they had experienced some splittage. This is mostly not a big deal, but it does make the potatoes uglier.

Pests

I don't really understand it. The root is edible. The leaves/shoots are supposedly edible. And everything I've read has indicated that the plant is non-toxic (no solanine, no oxalic acid, nothing). And yet, slugs don't seem to eat it. Other bugs pretty much leave it alone. I can't figure it out.

The only bug I've seen mess with the sweet potatoes in my yard were some kind of vine borer. I've had problems with vine borers destroying my cucumbers, melons, and squash, so I was pretty worried when I started finding them, they can destroy a plant and the crop pretty thoroughly. But with the sweet potato vines, it was a different story. They'd burrow in, dig out some of the inside, and that was about it. A section of the vine would get fat, and the surface would become kind of "barky", but the plant would just keep on trucking.

Soil Or Something Like It

I'd read that you need to plant sweet potatoes in "medium" ground. Too sandy and the potatoes get all long and spindly. Too rich, and they have other weird problems.

I didn't have a lot of dirt for my sweet potato bed, so I threw what I did have, added some compost, added some shredded up cardboard, and called it good. And that seemed fine. Another interesting factoid, I'm pretty lazy, so at one point I'd planted all my stuff in half of the raised bed (the raised bed being eight feet by four feet), ran out of stuff to plant, and decided I was done with it. I tossed a couple of chunks of really heavy duty cardboard, whole sheets, on top of the unplanted area (basically the other half of the raised bed), and quit right there.

Well, forgot about the cardboard, then the vines overgrew it and covered it completely. Later when I remembered, I saw the huge plant mass and just assumed that the cardboard had broken down. I was wrong. When I went to harvest, I found the sheets of cardboard still there, still whole. And under the sheets of cardboard were about nine or ten REALLY BIG potatoes. Right under the cardboard, on top of the dirt. How weird is that?

I would say that it doesn't take much to grow sweet potatoes. My next batch I'm going to try using about 25% dirt, 25% compost, 50% shredded newspaper and shredded cardboard, and just see what happens.

Eating the Leaves

I have read that the shoots/leaves are edible, similar to vine spinach. I've only ever found one recipe that actually said use sweet potato leaves, it was a Chinese recipe that had you steam the leaves/shoots, then pour a mix of a little shoyu, rice wine vinegar, and sesame seed oil over the top. I would love to find out ways to eat the leaves, so if you know of any, please email me at zachary@zone11.org.