Last year, I did an experiment where I took a phyllostachys dulcis shoot that hasn't formed its anchor roots yet, and forced it through the drainage hole of a nursery pot, filling it up with soil. As expected, it turned out to be a viable division as 4 rhizomes grew out of the based of that shoot after it was severed from the mother plant.
The biggest problem was that the shoot that emerged was too big, and had too many anchor roots that dried up it's little 2 gallon put very quickly. Last year I grew a rhizome close to the surface on purpose in order to promote the formation of smaller shoots which are easier to work with, and I can get plenty of which will be less of a burden for the mother plant since they are so small. As expected, the mini-shoots formed. This propagation method can be used for running bamboos that have a hard time running, or juvenile bamboos where you want to turn small shoots into divisions without draining the energy of the mother plant too much. These are clearly true shoots because you don't always have whip shoots available in the spring.
I'll guess I can name this shoot bud activation, air layering propagation.
Here's the shoots that were downsized while the shoots on both ends of the same rhizome are full size.
