Is it possible to grow sweet potatoes in the UK? Or, more specifically, is it possible to grow sweet potatoes in Northern England?
That’s where I live, and if I can grow them here then you should be fine in the majority of the UK barring maybe the highlands.
So, with that question in mind, I headed out onto a horticultural adventure. I had never seen a sweet potato growing before, only ever gazing upon the end result of the plant’s labours.
What does the plant look like? How does it grow? I had no idea, but like most of you I guessed it would be similar to a regular potato, I mean, they share the same name so they must be similar right?
No, not really. They are both root vegetables but that is as similar as they get.
Potatoes are part of the nightshade family whereas sweet potatoes are actually from the morning glory family. Their growing habits are also completely different, something we will get onto later.
Growing Sweet Potatoes
Now we know a little more about sweet potatoes let’s have a look at the process of actually growing them in the UK.
Sweet potatoes are commonly grown from slips, which is a cutting taken from a tuber and then rooted on.
You can do this yourself to shoots growing on a sweet potato you picked up in a shop, the problem is that the variety of sweet potato will be unknown and probably isn’t hardy enough to grow in the UK.
So, for your first year at least, you will need to buy these plug plants. That is exactly what I did, picking a few up from Suttons. This is what they looked like when they arrived.
Where To Plant Sweet Potatoes
For most of us, we will have to plant sweet potatoes under cover, you might be able to get away with them outside if you live somewhere with a unique climate like Cornwall but for most of us, it’s a greenhouse or polytunnel.
And that is exactly what I did, planting my sweet potatoes out into a bed in my polytunnel.
This is one of the reasons I really like having proper beds in my polytunnel and greenhouse rather than relying on growbags, it really opens up the number of plants you can grow.
The bed has a mixture of homemade and shop-bought compost and is nothing special, so should be a good barometer of how these plants will do in good, but not outstanding soil.
Calling what I called a slip is probably not quite true, the plants that arrived to me were an already rooted plug plants. I believe a slip in the true sense of the word will not have a root and will be a cutting direct from the tuber.
If this is what you buy to grow your sweet potatoes then you need to get it to root before planting out. Pot the cutting into a small pot filled with good multi-purpose compost.
If you have a propagator put the pot in there or alternatively you can make your own by taping a clear plastic bag over the pot.
After the cutting has rooted and turned into something more resembling my photo above then it is ready to be planted out.
There are more and more purpose-bred varieties that are becoming available to grow in the UK, these have been bred for hardiness and are much more suited to our climate than a general sweet potato.
The ones I grew are Beauregard and as I said earlier I got them from Suttons and they arrived as pug plants in the post. If you are interested in growing these then I will leave a link here.
There are a couple of other varieties that also work well in the UK apparently like Murasaki and Evangeline. I haven’t grown these so I can’t tell you what they are like, the only ones I have experience with are Beauregard.
I planted my sweet potatoes fairly close to each other as I have limited room in the polytunnel and had 6 plants to get in.
They are sprawling plants that spread out all over the place but planting them so close to each other doesn’t seem to have been much of a problem.
I have ended up with a blanket of foliage all over my polytunnel bed though which is a perfect hiding spot for pests like slugs.
How Do Sweet Potatoes Grow?
They really do resemble bindweed in the way they look and grow, it is easy to tell that they are related. You can take advantage of this and grow the foliage vertically but I decided to grow them along the bed.
The reason for this is that I am also growing watermelons at the back of this, exotic bed. This will be grown vertically up supports so won’t be competing for light or space with the sweet potatoes.
I have always found that growing like this is a great way to squeeze the most produce out of your polytunnels and greenhouses.
Have something growing on the floor and something growing vertically to maximise your use of space.
It took a long time for my sweet potatoes to get going, they just sat there at first and barely grew, I wondered if I had done something wrong.
Maybe the weather was still a little cold for them, even in the polytunnel or perhaps they were just establishing a strong root system.
As soon as summer kicked in they started to fly, growing rapidly and soon covering the entire bed with foliage.
I seem to have forgotten to take a photo of them at this stage, probably because not much happened, so here they are sneaking into the background of a shot of my pak choi.
You can see that they have grown a little, this photo was taken on the 9th of June, a whole month after planting.
And now look at them! They have completely taken over the bed and there isn’t one spot that’s not covered with the foliage from my sweet potatoes.
They took a really long time to show any signs of growth, but once they did start growing they grew at a really rapid pace.
I left these sweet potato plants a really long time, with the incredibly mild autumn we have had this year than plants haven’t started to die back until now, mid-November.
So it’s finally time to dig up those tubers and see what tasty treats I have waiting in store for me!
Hmm, so yeah, not exactly a feast.
So why did this experiment fail? Well, I have some ideas, the main one being that I didn’t get them in the ground early enough.
I was still constructing my polytunnel at the start of the year so these sweet potato slips didn’t actually get into the ground until early June.
The next thing I think may have worked against me is the beds themselves.
I don’t think I made the beds in my polytunnel big enough, and these sweet potatoes are not the only crop that suffered, so that’s another thing I will be addressing over the winter.
Trying Again Next Year
So next year, I will plant them earlier and into larger beds. I will be also adding a good thick layer of my homemade compost to get the nutrition levels in the polytunnel up.
This experiment has so far shown that the plants will grow and produce tubers, but it’s not going to be as easy as I thought it might be.
As for what to do with these tubers, I am hopeful I can keep them and use them to grow fresh slips off next spring, that way I don’t need to buy new plants.
Does anyone have any experience with this? let me know in the comments below if you do!