Crape Myrtles will always have some leaf scorch the first summer, despite adequate watering, and we should inform customers of that. Also, that watering needs to be frequent – apply enough water to replace what is lost from the rootball every day, twice a day the first two weeks if planted March thru September, then once a day for the next two weeks, then every other day for two weeks, then twice a week through October. Water to soak the surrounding area once a week, but just a few gallons per plant the additional watering days each week.
Do not let grass grow over the rootball and around the trunks of the crape myrtle. Do now stack soil onto 
the trunks of the crape myrtle. Mulch a 3ft. or larger circle. Remove spent bloom heads for faster growth and more blooms while you can still reach them safely.Do not prune off branches larger than your thumb unless you have good reason (hitting the roof, blocking the walk, or rubbing against another branch).
Leigh says
Hi..I have a 2 yr old crepe myrtle in front yard..lots of sun ..I live in florida..the tips of alot of the leaves are brown and dry..I dont know why..we get afternoon rain everyday..there is a weed barrier and mulch surrounding the tree..what should I do