please share ideas for growing BIG sweet potatoes, several pounds per plant

We've grown them for years on three different pieces of land.
I've never done soil tests nor really added any amendments aimed at growing a great crop.
The oldest orange potatoes I clone are going on 30 years now and the purples at least five.
https://permies.com/t/17569/perennial-vegetables/sweet-potato-propagation-harvest
I've read where they can play out eventually but I was able to grow a twenty pound cluster (and also an 8#  and a 10#)from the oldest strain just a few years ago....and a few huge purples last year but not all of them and have not been able to duplicate that success.....some years are okay to good but not outstanding.
pictures below are of the twenty pound plant!



Here's what I've read recently that I see lacking in my methods ...

...choosing the potatoes for slips from plants producing at least four nice potatoes.

...feeding the soil, especially potassium.

...watering often enough they don't wilt.

...not letting the vines root along their length

...mulching, (we only do sometimes)

This years crop of purples were average size and only around a pound per plant except for three plants that produced the cluster of at least four good ones...they were still just around two pounds total.  I have an occasional single 3# potato from them though so I know they are capable.

This years orange, old variety, cut leaf produced a couple plants with one or two nice size but mostly small clusters of roots.

Some in tubs, some in holes I added sand to and some in clay that dried to a brick but still had similar size potatoes.

I suspect lack of nutrients rather than soil tilth.
The 20# plant was a left over slip, planted late in unworked ground in the front yard .. it also had a pile of pine logs near by from a recent tree removed from that yard...no amendments and we almost forgot about it until the rest of the garden crop was dug.

I hadn't thought about discouraging rooting along the vines' travel along the ground. Might have to give that a go this season...always looking for the cool ways to tweak the system. I didn't cover the surface with biochar last year before planting because I couldn't bear to have that much exposed soil. The plants established quickly in spite of the lack of extra heating so I will just plant directly into mulch this time as well.

I think allowing rooting along the vines in a longer season works and they will make more potatoes  along there also.  Here, I think it just takes energy away from the main plant.

Here's some photos of information from a book put out by our local extension service for this state...usually good info if we ignore the chemical solutions promoted and they do acknowledge organic growers now😊

As a long time grower of sweet potatoes in several regions, I can vouch for not letting the vines root along their length, unless perhaps you are in so tropical a climate as to have them basically become a perennial groundcover, and even there, finding the largest roots to harvest would still be a challenge.  Raised beds and mulching help with this, but in wet weather roots will grow down through mulch, and then going along the rows and lifting the vines and setting them back down helps, and/or stuffing coarse mulch, bundles of sticks, etc. up under there as well.  
   Not letting the leaves droop from drought is also important.  In fact this is good for just about every kind of vegetable.  When I was growing for high-value organic markets I was taught that if you see foliage droop on anything, even if it recovers overnight, you are losing yield and quality.  Although yes, in a homestead situation resilience is also important, and you will still get a yield in spite of this.  A long drought followed by heavy rain can also make roots split.
    Most important of all, though, is to work toward what I call a "fluffy" soil....this goes for carrots as well.  Neither likes a heavy clay and it will lead to small twisty roots on both.  Sandy soil is ideal, good loam is good too.  If you have clay the answer is finely divided organic matter incorporated in.  I used to make this by running a mower over dry leaves, grass, etc. in the pathways between those beds allocated to these crops, and then dig and/or till this into the beds themselves...up to an inch or two depth of "powder" per year.  A bit of urine helps counteract the nitrogen uptake issue with this kind of organic matter use, but fortunately neither sweets nor carrots like a lot of N anyway.
   

I haven't worried much about maximizing production as I've mostly been focused on breeding them for growing as seeded annuals. I do think that allowing them to root along the vines, especially if they have a trailing habit takes away from a nice harvest of larger roots and instead makes lots of little ones. Worse they are all spread out and hard to find and harvest but you might get by with it if you have a longer season and don't mind digging a crater to find them. I grow them mostly in pots and have selected for bushy, non-trailing vines and a clump of nice roots directly under the primary stem: I think those traits would also be nice to have even if growing in the ground.

I also haven't worried much about specific soil nutrients or anything else that would require me to test for or purchase anything, I just grow them in what I can scrounge up around the place. I do think though that a nice loose soil helps encourage larger roots and keeping them well-watered helps too. One year I saved a bunch of yard clippings and leaves and kept them dry in bags in the shed. In spring I mixed that up with some pretty decent compost and a little plain garden soil. That was the best ever as far as production, I got two to four pounds per 3.5-gallon pot. *If you grow in pots, especially small ones it is important that the drain holes be buried in the ground, so they don't dry out so fast and so feeder roots can exit into the soil below and never move the pots once those roots have established.

I saw a fellow on YouTube that grew them in large Rubbermaid tubs with a very specific soil recipe of purchased potting mixes. He had a fantastic harvest, many pounds per tub. It looked like most of the space in the tub was filled with just sweet potatoes. It was interesting but not something I would do because it violates my buy nothing policy, plus I don't need hundreds of pounds of sweet potatoes as there are only two of us here to eat them.  

Next year though, I am going to revisit the issue of maximizing production and have already stockpiled several large bags of leaves, weeds and grass to fill my pots. As I move to this new phase of my breeding project, I'm setting a goal of averaging three pounds per 3.5-gallon pot.

I know nothing, and I'm a terrible gardener (yield wise, anyway), but if I could only grow one plant for food, it'd be the sweet potato.  They love it here in the desert southwest.  I've had plenty of failures with them (watch the video for proof), but all in all I generally do well growing them.  I went crazy this year and planted about 70'ish slips mostly in containers, and about 20 or so in the ground.  I planted two to three slips per 15 gallon nursery pot (closer to a 5 gallon bucket in size).  I haven't harvested yet since there's still some time left until my first frost.  

The first plant I pulled was from a plastic 10 gallon nursery container?  It's about the same diameter as a 5 gallon bucket, but several inches shorter in height.  I used a mix of old potting mix I save every year, and I mixed in a bunch of my chicken litter/wood chip compost.  I fertilized with some Alaska fish fertilizer a half a dozen times up until about July, and then they just got plain water (very hard, mineralized, chlorinated, city water).   I'm dreaming of 200lbs, but I will be thrilled if I get over 50lbs, lol.  The first plant I pulled got me all excited because it had 8lbs exactly, then I pulled three other GIANT plastic containers, and only 8oz total from all three!!!  I was bummed.  

Every plant in the yard came from three organic Stokes purple sweet potatoes I got at Smith's grocery store in February.  I started propagating them in February, and to my surprise they started forming shoots within days (first time that's happened).  I was up to my ears in slips/shoots and from those three potatoes I got probably over 150 usable shoots.  I gave some to the veterans at the veterans home I work at (super cool to see them growing at work!!!), and a bunch of others to my neighbors.  I started putting them in grow bags and plastic containers in the beginning of March in my greenhouse, then I ran out of room in the greenhouse, and started rooting them is large plastic red cups so I could transplant them to larger containers outside around May.  

I'll upload some pics of what I actually got in a few weeks or so (first frost here).   I can't upload the iphone images from the phone I was using.

Here's a cheesy video of my rambling about it.  I'm not too good at videos.  I did use ai for the thumbnail, and it did a great job!  

edit, let's see if my other pictures will work.

edit again.  I figured out how to convert them.

How do you keep them for next years planting?    Will the tuber survive all winter in the fridge or root cellar?  

This year I got starts from Baker Creek.   https://www.rareseeds.com/.  I would like to keep these genetics and protect them.  

I live in the north and I am thankful to get any sweet potatoes.   I got the hardiest, short season, cool summer tolerant variety I could find and put them in my best soil, in the sunniest, most protected location.   I put them in after the soil had warmed and the harsh winds of winter had passed.
I did not add any nutrient as they were growing but the soil they started in was quite rich from well rotted manures.  

The plants were very healthy looking when they were growing and even tolerated a couple light autumn frosts!
I have not dug them all up yet but I am getting about 10 pounds per plant.  

Hi Samantha,
I don't cure mine, I tried it once and they started to mold.  I just throw them in my room temperature pantry (well I try not to use a heater, so it's probably 60f-70f most of the time during the winter) and they last until spring.  I ate all of last year's so I had to buy new ones this season.   I can start so early (Feb-Mar), and harvest so late (Nov-Dec) mine don't need to stay in storage but a few months or so.  Rarely do they rot, but some will every year.  I just toss them out to the chickens/compost.

Ten pounds per plant is awesome!  If I can get half of that per plant I'll be one happy guy!

Good luck!

Joshua Bertram wrote:Hi Samantha,
I don't cure mine, I tried it once and they started to mold.  I just throw them in my room temperature pantry (well I try not to use a heater, so it's probably 60f-70f most of the time during the winter) and they last until spring.  I ate all of last year's so I had to buy new ones this season.   I can start so early (Feb-Mar), and harvest so late (Nov-Dec) mine don't need to stay in storage but a few months or so.  Rarely do they rot, but some will every year.  I just toss them out to the chickens/compost.

Ten pounds per plant is awesome!  If I can get half of that per plant I'll be one happy guy!

Good luck!

Excellent!

Thank you Joshua!

I guess I am used to the store bought ones that seem to go bad in a few weeks.   Hopefully these garden beauties will have the health and vitality to hold on until spring.     I am so excited to be able to make my own sweet potato slips for next year!

I'm just catching up here...thanks everyone for sharing experiences and information.

Samantha, 10 pounds per plant is excellent!
Can you share your 'how to'?

As far as curing them, I dig them up and lay them out on paper for awhile in the shade...wipe more soil off of them and bring in the house to lay out on paper some more....at least a week or so but longer doesn't hurt.
I've never understood the use of humidity for curing them...it myst be a commercial way for the stores but as you say they don't keep well.
I like to get the skin as dry and tough as possible, then sort by size into cardboard boxes or paper bags.  We have always stored them in our living room where the heat is. Warm, above 55F is good...cold will cause them to rot.

I've had them keep well for a year but we usually eat them earlier.

I had grand(iose?) plans to grow lots of sweet potatoes this year. I started early in a pot on a sunny windowsill...

planted slips out to the garden area protected by a fence...

The deer LOVED this idea, the early leaves are very nutritious and tasty - perfect to help out the local deer population explosion. The fence was no barrier at all to motivated deer.

In the end, the plant in the pot survived, produced about 470 grams of tubers in a pot of about 5 liters.