How to prune crapemyrtle to tree form
Q: We planted a crapemyrtle that has blazing red flowers and black leaves three ears ago and I want to trim it into a tree. This variety grows ten feet tall. I need details about trimming it in fall.
A: I would remove all branches from the lower third of the crapemyrtle. Then remove any branches that cross through the middle of the top.
Leave it alone until late spring, then remove the weakest of the interior sprouts that appear.
I like this description too: