Some cuttings are slow to root and I have had some take as long as five weeks. If they are still green and you have left a leaf node on the stem of the cutting, it will eventually root. But if you did not leave a leaf node on the stem that is under the soil, it will never root.
Nodes are also on the stem very close to where the cutting was attached to the tuber. It is best to take a cutting by cutting it off the tuber the width of nickel above the tuber.

Ted,

In every case I believed I was cutting as close as you suggested. There were two very small triangular shaped leaves (cotyledon leaves?) near the base of the cut stem. In most cases, they fell off themselves, but if they didn't I took them off.

I did not, however, take any additional leaves off unless leaves were very close to the end of the cutting. For the vast majority, I didn't have to take any additional leaves.

So I suppose I'm unsure whether or not I have left a node, as you say is needed. I thought that as long as my cut was very close to the tuber, that was sufficient. In some cases, the sprout grew from an under side of a crown and ended up rather "J" shaped. When this happened I cut off the curved part at the bottom but left the rest. Maybe this is where I'm running into trouble??

Of the nearly 300 cuttings I have now, I know that 73 of them have definitely rooted because they have added considerable growth. I have another 42 which have not added growth but should have because they are of the same varieties and taken roughly the same time as the 73 which have added growth. Then there's another 190 that haven't been growing long enough to know for sure.

I am worried that there may be more that are just staying green and not rooting. So I thought to transfer each from where they are to new cells. The soil is loose enough that it will fall off the plant, unless there are roots. So any that have not yet developed roots, I plan to put into rooting hormone (Roots.)

If there are no roots I plan to cut the lowest set of leaves off the cutting and, after dipping in the rooting hormone, replant.

My theory is that if I do not have a node already at the bottom of the stem then the node where I've removed the leaves should form roots instead.

Hopefully this is a plan.

Cheers,
Russ

Seems to me that where there is life there is hope.