Trimming the canopies is the last step you need to take when it comes to trimming crape myrtles. There are two things you need to do with your crape myrtle canopies: First, remove all twigs and limbs that are smaller than the diameter of a pencil. Do this throughout the entire tree. This is probably the most time consuming part of trimming your crape myrtle, but do not skip it. These small twigs and limbs are considered weak growth, and provide little value.Secondly, you want to thin the canopy of your crape myrtle. The goal here is to have a symmetrical canopy with limbs growing evenly in all directions around the tree. To start, thin out clumps of limbs growing in the same direction, limbs that criss cross through the canopy, or limbs that are rubbing up against one another. Lastly, don't be scared to do this! If you make a mistake, or are unhappy with how your tree looks, there is good news...it will grow back! And next year you can try again and make your corrections. So don't worry about perfection, just get it done!