Found this - hope it helps.... Wait for the Crape Myrtle to sprout. In the late spring you should be able to see the new growth. Look for the smaller, weaker stalks at the bottom of your plant. These are commonly called waterspouts or suckers. Pick out the strongest stems at the bottom of your Crape Myrtle. Depending on the type of Crape Myrtle and the amount of pruning that has already been done, you should find between two and four strong stems to be your base. Remove the weaker, less sturdy branches at the base of your tree. This includes any new growth at the base. Work your way up the Crape Myrtle and clip of any limbs or new growth until you only see the strong stems. Step back as work so you leave an even top set of limbs. Stop before you reach the top. Make sure you leave enough new growth at the top to have a full blooming tree. Form the top of your tree and remove any dead limbs. Prune your Crape Myrtle tree every spring. After you prune, but before your tree blooms, it should look similar to a large bonsai tree. Do not cut all the new growth of the top of your tree.