I’ve always been a big fan of Sweet Potatoes, especially baked in Maple Syrup with a Sunday roast, but this is our first year growing them properly.
A couple of years ago we bought a small potted Sweet Potato plant from BnQ in late Summer. We planted it out in the garden, but it didn’t stand a chance that late on in the season. It put on a small amount of foliar growth, but yielded no Sweet Potato tubers underground.
Last year we tried planting a whole tuber of our own. We bought a large Sweet Potato and planted that in a bucket of sandy soil. It rotted for 2 months and did little else…..
This year we decided it was time we actually did a bit of research and found out how to grow Sweet Potatoes properly.
Did you know that the Sweet Potato isn’t a Potato at all, it’s actually a member of the Morning Glory (Convolvulaceae) family rather than the Potato (Solanaceae) family. This is why Sweet Potatoes aren’t cultivated in the same manner that you would cultivate a typical Potato.
We found out that it isn’t the tuber that should be planted at all, but the ‘slips’. This is the name given to the shoots that will grow from the tuber in the right conditions.
What are the right conditions?
After some research we decided to use a method whereby you sit the tuber in a jar of water in a sunny position, with it’s most pointed end facing downwards. There seemed to be a lot of evidence of people having success propagating Sweet Potato slips like this, and having already failed at getting results by planting a tuber straight into the soil, we didn’t want to go down that road again!
We put our Sweet Potato in a jar of rain water in late April. It already had the slightest suggestions of shoots sprouting from it’s rounded end. It seemed to take an age for it to sprout any roots from the pointed end, but when they eventually started to sprout you could really see the effect their presence had on the rate of the foliar growth. By mid-June we had enough slips to start planting them.
I took cuttings of approximately 8”-10” inches in length. Stripped all of the leaves off, leaving only the final three sets of leaves closest to each cutting’s growing tip. Once buried, the roots grow from the nodes where the lower leaves have been stripped off. I planted six ‘slips’ in a container, burying each on up to it’s lowest set of remaining leaves.
The container I used was one of the large recycling boxes provided by the local council. I’m not too sure how but we seem to have acquired three or four spares over the years. Most of them are full of 12″ records, but at the time I was looking for a container there was one stood empty and all other more orthodox garden planters and such were full of chilli plants.
There are three main advantages to planting Sweet Potato slips into containers in the UK……
- The container’s sides can be warmed by the Sun, and so keep the roots much warmer than they would be if planted in the ground. Due to it’s sub tropical heritage the Sweet Potato needs as much warmth as we can give it on our cold little island.
- The container is portable. As above, because of it’s much warmer native environment the Sweet Potato really needs the warmest sunniest and longest season possible. Planting in a container means you can move the plant into the greenhouse as the weather gets colder, or even into the house eventually if needs be.
- Finally, any plants in containers, Sweet Potatoes or otherwise seem to have quite an advantage against slug attacks. Not invincible by a long shot, but I have noticed that all of my container plants have a much lower slug attack rate than their equivalent counterparts planted straight into the ground. This has been one of the rainiest Summer’s on record in the UK so our slug population has boomed, both in numbers and actual physical size, so any extra protection is worthwhile!
It took a good few weeks from when I first planted my slips before they started showing any signs of growth. In fact two or three of them actually shrivelled up at their growing tips. Around the beginning of August we started to see some fresh foliar growth sprouting from the lower nodes. Even the slips that shrivelled at the tips were starting to branch out at their lower nodes. I suspect the long pause before any visible growth was the period in which the slips were beginning to establish their new root systems, and so all energy was being conserved for that.
If the weather behaves as it should we can expect our first frost to be somewhere around the October mark. Given my slips’ rather slow foliar grwoth thus far I can’t imagine that I’ll have the fully established mass of vines that I’ve seen on other (non UK) grower’s Sweet Potato plants at the time of harvest by October, so I plan on bringing my container into the conservatory some time near the end of September and hopefully the Sweet Potatoes will be ready for harvest by Christmas.
As you can see from the photo at the top of this post, I still have the original tuber and it’s still throwing out fresh slips quite happily, so I think, rather than staring the whole process again afresh next year, I will plant a few slips into small pots in Autumn and see if they can be over wintered for an early start and a longer season next year.
Watch this space….
This is what my slips were looking like last week, when this photo was taken.