I’ve decided this year (2024) I’ll have a crack at growing sweet potatoes. From what I’ve read it should be possible to get a crop as long as they are started early enough and we have a reasonable summer. They are a tropical plant so they are a bit marginal in the UK.
I’ve decided to try growing them this year because I have recently got access to a fairly large plot of land. The issue is the land is about 90 minutes drive away so I’ll need to grow things that don’t requite much tending. The ground has also been untouched for about a decade so it’s covered in weeds, particularly brambles. We’ve been working hard to get it cleared but it’s an uphill battle.
At end of January we bought a sheet of damp proof membrane and laid it over part of the lawn. That gives us 60 sqm of ground that is protected from the light and warmed by the black plastic. The idea is to get all the weeds to sprout and die under the plastic. I’m not sure how successful this plan will be, I think ideally we’d have the ground covered for much longer.
Anyway, on to growing sweet potatoes. The variety we have is Covington which is an orange-fleshed, smooth-skinned, rose-colored, table-stock sweet potato developed by North Carolina State University (NCSU). There’s a whole website dedicated to sweet potatoes from the North Carolina Sweetpotato Commission. Looking at the climate in North Carolina it’s not that far from what our garden experiences. Summer highs are around 30degC and winter lows around freezing, where I am is maybe 5degC cooler typically – we always get at least one decent frost in winter.
The sweet potatoes I’ll be using were bought a the supermarket (Tesco). My understanding is that some supermarket potatoes are sprayed to stop them sprouting so fingers crossed that’s not the case here. I’m going to start by cutting the sweet potatoes in half to give two pointy ends. This is because the slips, new sweet potato plants, only really sprout from the pointy ends. Take the potato halves and place them in a dish with about a centimetre of water and put them on a warm windowsill. Keep this water fresh and in about a month you should have new slips forming. I’ll be cutting my potatoes on the 19th Feb.
Once you have a decent sized slip (anything over 5cm should do it) snap it off the potato, trim back any low leaves and then stand it in a glass of fresh water. Any part of the stem in water will grow roots. I plan on leaving my slips until they get to about 20cm tall, by that point they will probably have started to form a few roots of their own, especially ones that forms low down on the potato. You’ll probably find the potato itself starts to grow roots too.
Once the slips have a decent number of roots they can be potted up. Leave them to become established in the pot. They can be planted out at the start of May or maybe a little earlier if the weather is looking good. Plant 30cm between plants and 70cm between rows. They might need to be covered in fleece at the start to help them adjust to the outside. They will be ready for harvest late in the year, second half of October to the first half of November.
Progress
The initial sweet potato halves went into water on the 19th of Feb, as of the 5th Mar there is no sign of them sprouting slips or of the potatoes growing roots. I suspect I might have potatoes that have been sprayed with an anti-sprouting agent. I’ve given then a good scrub (as recommended here) to try and remove any anti-sprouting agents and changed the water they are sitting in.