Many people ‘top’ their crepe myrtles, believing that by doing so they can increase their flowering. This is not a good practice. It will weaken and make for a less than attractive plant, whether one decides to train it into a tree form, or a free form.
Each spring I remove any cross branchings that have occured from the prior seasons growth. I feed my crepes a twice yearly handful of bone meal, never spray them or give them regular waterings. Their beauty only increases. We live in the north Texas area, prone to dry spells and excessive heat. These plants are my absolute favorite. Two of them flank my west exposure, one the south, and two others to the east. They never cease to amaze me! I am blessed. I hope you are too. There isn’t a more resilent plant for this area. I’m preparing to move three additional plants into my yard this fall.