I keep all my plumeria about like Patty does, at a manageable 6' or less height. I have to move mine inside for the fall/winter months, so size is important to me. I try to wait until the branches/tips are at least 24", are a nice and plump 1 - 1/2" thick, and the base where the cut is made not too green. To get these parameters, I usually take cuttings mid to late summer. I am no expert here, far from it, but this works for me when I am rooting cuttings. The base/trunk of some of my plumeria are 4-5" thick. I have never taken a cutting in that thick wood. Thus, I don't know how a cutting that thick would root or what sort of branching/tips would form from a cut trunk. I feel sure there are those, particularly in FL and S. CA that have done this and can tell you their results.
