sweet potato slips...how long should they be?

Mine have always been fairly long...8-10" maybe.
Then I remove most of the leaves and plant them deep, up to the top few leaves left.

This year I started them later and was able to set the flat and jars of potatoes for starts out in the sun thinking there would be less shock when I eventually plant them.

I think they are shorter slips since they have had that nice sunshine and aren't leggy like when I grow them in the house with much less light.

So now I wonder how short a slip will produce potatoes?
Does it matter?

Sweet potatoes are very hardy and most any slip will grow. That being said, the roots primarily grow out of the leaf axil (where the leaf grows out of the stem). So best practice is to have two leaf axils under the ground and at least one above ground. This gives optimal amount of root growth near the soil surface for tuber production and leaves one above ground for fastest leaf growth. Leaving two above ground is fine as well, but much longer than that and you're just stressing the plant to try to sustain that much more vegetable life before it has roots.

thank you Nathanael!

That's exactly what I needed to know.

number of leaf nodes matter more than length....now to go count them!

I try to plant my slips so there is one more node underground than aboveground. By having the balance skewed slightly more towards roots, it’s less stressful for the plant to establish itself. Therefore, I try to cut slips such that they have an odd number of nodes, usually three or five, depending on internodal distance (which varies by variety). If your nodes are further apart from one another, slips with three nodes will be easier to work with than five, which may make for excessively long slips. If your nodes are more tightly spaced, five will make more sense. Experiment with it and see what works for you.

Another tip: don’t plant your slips upright like a tree sapling. Instead, lay them down horizontally so that when the nodes develop into storage roots, it gives them more space from one another and prevents them from crowding each other out. This makes planting easier overall because you don’t need to dig holes for each slip. Just make a trench with a hoe and lay them down. The only caveat is that you may need to stay on top of watering more frequently, especially early on, due to planting more shallowly.

thank you jonathon!

I can't watch videos but your explanation was great.
For some reason I never considered planting the slips horizontally although I do that for tomato plants sometimes.

and over decades of growing sweet potatoes I rarely paid attention to the number of nodes until this year when my slips seemed so short.
This could explain why I sometimes have a few plants with nice vines and no roots.

Judith, I rarely watch a posted video, but I did glance through that one. It was from a university in Louisiana; I think they developed the variety Evangline and some others as well. The segment about vertical verses horizontal planting was interesting, showing in their example an increase in "market sized" roots by planting horizontally. I'm sure that is completely true in their example of a giant field planted and harvested by machines, but it is also totally wrong from my perspective. Just another case of "it depends" that would take a hundred pages to fully examine. The genetic makeup of the species is extremely complicated and does not follow simple Mendelian inheritance rules, that they don't breed true is an understatement.

The varieties they tested were Bayou Bell, Beauregard and Orleans. I've grown all of the them and they are descent sweet potatoes, but none of them met my criteria for continuing with. He also said that, in their tests, the biggest difference in yield was between irrigated and non-irrigated fields rather than between planting orientation. I grow mine in pots as small as 3.5 gallons and get an average of around four pounds of uniform roots per pot, more or less depending largely on how diligent I am in keeping them watered.  Last year thirty pots yielded about 135 pounds.

As far as the size of slips, they don't have to be large. Ideally for me a single healthy node below ground is actually best but I normally plant two below ground unless the single one is developed in an optimal way, and I plant vertically. I also like a slip to have few if any actual roots when I plant it. Just a nice healthy stem with a node or two below and at least one healthy growing tip and keeping it well watered for a few days, seems to be all that's needed and in fact I think better for production. The overall length of the slip might depend a lot on the internode length of the variety. A slip for a large vine with long internodes might be six or seven inches, or maybe even more. A plant with shorter internodes might be fine at just three or four inches, I have planted them even smaller than that.  

thanks Mark!
Next year....I'll pay more attention to number of nodes and distance between.

I did plant most of my slips this year unrooted and then kept them watered along with good rains.   The plants looked way less stressed than when I plant well rooted slips.

The most productive plants we have grown were long slips stuck in the front yard around old pine branches...8-20# each plant!.  I had planted them as an afterthought with some leftover slips...then forgot to harvest until late and the voles had not found them.....surprise

I've tried and have not been able to reproduce those conditions successfully.

My orange potatoes have dwindled in production (although they are the ones that did so well in the front yard just a few years ago) and even the purples produce only 3-4# sometimes all from one sweet potato.

I am watching the purple vines for seed this year since they like to flower... getting tempted to try some from seed after reading your thread.