Year's supply of sweet potatoes

[ameno]

Today I used up the last of last year's sweet potato crop. I dug them up at the end of October last year, so that means they lasted me 10 months. I was really surprised by how long they kept - this last one was still just as good as the early ones, still tasty and still firm and good, with no signs of shrivelling, rotting or going woody and tough.

The plants seem to be doing even better this year, and I think I'm probably in for a bigger crop, so I wonder if I'll manage a full year's supply of sweet potatoes?

[Nicos]

Well done! That’s very impressive - what weight did you dig up last year?
- do keep us updated.

I’ve never tried to grow them. Well - not quite true…I did grow some slips once and then watched them rot
Any tips ?

[Snoop Puss]

Congratulations, Ameno.

I had no success with sweet potatoes the year I tried to grow them. Lots of vines and not a single potato.

Did you do anything special prior to storing them? I remember reading somewhere about how they need very high temperatures and humidity before being stored and this, plus my total lack of success at growing them, put me off.

[ameno]

Well done! That’s very impressive - what weight did you dig up last year?
- do keep us updated.

I’ve never tried to grow them. Well - not quite true…I did grow some slips once and then watched them rot
Any tips ?

I had a total of 39kg last year - 34kg of variety T65 (11 plants total, my eight best plants gave an average of 4kg per plant), and 5kg of Erato Violet (5 plants total).

I've found the plants themselves are pretty much foolproof as long as you don't let them get cold. Sweet potato slips and cuttings will root in a glass of water in a matter of days, with nearly 100% success rate, after which they should be potted into 9cm pots before planting in their final position 2-3 weeks later. And the plants are very tolerant of a lot of conditions.
The potential difficult part is actually getting a decent crop from them, rather than just nice looking plants with nothing underneath.
Warmth is naturally important, but soil temperature is more important than air temperature. I grow mine outdoors, but through black plastic. Although admittedly T65 is renowned as both high-yielding and more tolerant than most of cool temperatures.
To get a good yield, though, I think space is most important. I now grow mine with a generous spacing of around 18 inches each way (9 plants in a 6ft x 6ft square), and yields per plants are about three times what they were when I grew them in a row with 9 inch spacing, or when I grew them in pots (even in a large, well-watered pot grown in my conservatory, my very best yield was 1.5kg). There are far more medium and large tubers, and far fewer unusable rat tails this way, too. The vines themselves will trail to over six feet in all directions by the end of summer, so are liable to smother nearby plants. Assuming you haven't overdosed with nitrogen fertiliser, I've found top growth to be fairly proportionate to tuber yield.
Other than that, I just keep them well watered in dry periods and feed them with tomato feed every 10 days or so starting in late July.

Did you do anything special prior to storing them? I remember reading somewhere about how they need very high temperatures and humidity before being stored and this, plus my total lack of success at growing them, put me off.

They need a spell of warm temperatures and high humidity first to "cure" them ready for storage. Stuff you read says 27c, but they don't actually need to be that warm. Anything over 20c is warm enough, it's just at the lower end they take longer to cure.
I rub off excess soil (never wash them), lay them out on trays in a single level, and put them on top of my kitchen shelves for 2-3 weeks (warmest and most humid room in the house).
After they have cured, I transfer the trays wherever I have room for them around the house. Ideal post-curing storage temperature is apparently around 15-18c, but I find they keep just fine at room temperature. I keep some in the kitchen, some in the bathroom, and some in the understairs cupboard. The important thing is never store them cold (never put them in the fridge, or a shed or outhouse).
Smaller ones, especially thin ones, need using up early as they will shrivel quickly. But anything of a half-decent size will keep ages. Even half-used tubers, from which you have already cut a piece, are best just kept at room temperature. The cut edge will dry over and they will not rot (although they may start to dry out after a week or two).
They are liable to start sprouting after a while, but the sprouts can just be rubbed off periodically. Unlike potatoes, sprouting does not render them toxic or anything like that (in fact, sweet potato leaves are edible, too).
And indeed you can sprout a tuber come spring to produce that year's slips, rather than buying them. It's much cheaper, and you can start them a bit earlier this way (slips bought online always seem to arrive really late). I bought my T65 slips in 2018 and have just been propagating them myself ever since.

[Snoop Puss]

Fantastic info, ameno. I will try again. I grew them at quite a distance from each other - space is something I'm not short of - but maybe I didn't water them enough. As for storage, I probably won't grow anything like as many as you, as I have very little storage space of the kind of temperatures you're talking about. But enough to make a few plants well worth while.

I will be able to buy slips at a local nursery to start me off. Brilliant.

Thanks.

[Nicos]

Very interesting…thanks for sharing ameno.
I may well give them a go then next year . Thanks.

[ameno]

Fantastic info, ameno. I will try again. I grew them at quite a distance from each other - space is something I'm not short of - but maybe I didn't water them enough. As for storage, I probably won't grow anything like as many as you, as I have very little storage space of the kind of temperatures you're talking about. But enough to make a few plants well worth while.

I will be able to buy slips at a local nursery to start me off. Brilliant.

Thanks.

Good soil helps a lot, too. Fertile, that is.
They say that sweet potatoes prefer loose soil, but I my soil is a clay-loam on top of a sticky yellow clay subsoil, and they seem to grow with no problems in that. Year before last I even had 10 inch or more long tubers extending straight down into the yellow clay like carrots.

One other thing I should mention is that sweet potato tubers are quite brittle, so care must be taken when harvesting. Especially so if you grow them on heavier soils, where they seem more inclined to grow longer and thinner (like a carrot) rather than short and fat, as they are liable to snap in half as you try to get them out.
I've found the best way to dig them out is to loosen the soil around the plant with a spade or fork and then dig them out with just your hands. It takes a bit longer, but you'll have far less damage that way.

As for storage temperatures, normal room temperature is fine, really. It's slightly warmer than ideal but they still seem to keep just fine (they just sprout slightly more, that's all).

[Snoop Puss]

We'll be toasting you next year with any luck, ameno. Thanks. I'm bookmarking this thread for future reference.

[ameno]

Well, I've finished digging up all of my sweet potato plants, and the total this year is 42.5kg, from the same numbers of plants as last year.
Might just about be enough to last the whole year. We'll see.

[Nicos]

Very , very impressive ameno . That really is quite an achievement!

Could you possibly keep us updated next year in real time as you prepare them ?
I’d need to grow mine from shop bought, so I’d have no choice in variety, although I sometimes notice that we have more yellow fleshed ones, but that’s rare.

[Snoop Puss]

Wow! That is a really impressive harvest, Ameno. Congratulations. And thanks for all the info you've provided on this thread. Really helpful.

[Nicos]

^^^^ seconded!

[ameno]

An update on this.
I still have a couple of kilos of last year's sweet potatoes left, and I am now starting to dig up the new ones (since a light frost caught about a third of the leaves).
So they've lasted me the year, and probably a little more besides. And they have all kept fine, with no rotting and no significant dehydrating. They still taste good, aren't too dry, and aren't at all tough or anything like that.

I've only started digging out the purple ones so far, and the yield from those is so far comparable to last year.
All of the sweet potato plants have certainly produced a lot of leaves this year, though. I planted 12 plants (9 white, 3 purple) through a 6ft x 9ft sheet of black plastic in the largest bed at my allotment. The vines have completely now covered some 90% of the 13ftx16ft bed, as well as spilling over onto the paths on both sides, and climbing up into the adjoining bed on one side.

[Snoop Puss]

Congratulations, ameno. A whole year's worth of sweet potatoes in good condition... that's really impressive.

Hope you get a similar crop this year.

[ameno]

Just finished digging all of the plants up.
This year's total as 29.5kg of white sweet potatoes, and 8.8kg of purple, for 38.3kg total.
The purples actually did slightly better than usual, but the whites were disappointing. I put it down to the gloomy, damp summer, although I also suspect I didn't feed or water them quite enough. Because of the damp weather I didn't water them as often, which also meant I didn't liquid feed them as much, however when I peeled back the black plastic to dig them up, I found it to be pretty dry underneath, despite all the rain we've had in the last month or so. Clearly it sheds more than I thought, so I'll have to water them more in future, even in damp weather.