Though I had heard of this many years ago, I didn't give it a try until this summer.
Put simply, it's removing the top few inches of stem, complete with leaves, and rooting it. Gradually it will form a tuber identical to the parent plant. I took three cuttings of the ones I had selected and my success rate was 66% so I'm bound to do better next year.
I'll unpot one tomorrow to show the tuber.
These two even have buds!
