At the very least, remove the head of the bloom stalk as soon as you recognize it. Some semps will set some offsets on the (remaining) bloom stalk and some will not. Seems to be related more to the variety which will do that. I think surgery is the most reliable way to go, since it seems to take the cells that are triggering the flowering away from some of the divisions, allowing them to develop back into normal rosettes that regenerate with offsets.
Another technique, called "coring", is to remove the central growing portion of the rosette which causes the semp to develop offsets. One of these days, I want to try coring on blooming semps to see if that is a better and safer way trigger offsets on a blooming rosette.
