pruning Crepe Myrtle
I'm NOT one of those crazy Crepe Myrtle "beheaders" but need to know how and when to prune our small one near our front door. It has 3 trunks and stands about 4 1/2 to 5 ft. tall but is very much encroaching upon our sidewalk and front door area! I really want it to grow UP for a little while and then OUT. How and when do I prune it?? Thanks!