No need to cut them back in Florida, Valery. Mine bloomed right through the winter last year, and I have one in bloom right now, despite the cold nights we had this week!
They do get sort of 'tired' after a few years, so it's not a bad practice to start new plants every few years from cuttings. My biggest one is 9ft tall at the moment, but it's really not as robust as it used to be so I'm ready to re-start it next spring, or get a few new ones.
