Crepe myrtles should be transplanted when they are dormant, not when they are in bloom. The best time to transplant a crepe myrtle is early spring or fall. In early spring, the tree can be pruned before moving.
Crepe myrtles flower on the new growth of the current year. If a tree is transplanted before blooming begins in early spring, flowering is not affected. Transplanting after flowering is complete does not affect flowering for the upcoming year. When digging up the tree, be careful to keep the root ball intact, especially the major roots. Plant in a sunny location and water well.