Propagating from sports
I have a Harrison's Yellow that I have been transplanting sports/offshoots from for the last two years. Last spring I cut back the sports on advice received here. The transplants promptly sprouted making me wonder if I should have waited. This fall I planted another eight or so smaller plants and didn't cut them back. Most have only a few leaves at the base but two have leaves all along the cane. I'm coming to the conclusion it is best not to cut back and let the transplant decide how much growth it can support.
That gets us to this year. The parent plants have sports again. I'm thinking I should severe the roots going to these sports to encourage independent root growth. When is the best time to do this? The sports are currently about two feet high.