How prune crape myrtles into small trees?

Thanks to David Slevin for his pictures and this great question about pruning crape myrtles.

David planted eight ‘Tonto’ crape myrtles from 2-gallon containers four years ago, and they’ve filled in quite nicely, but now he’d like to shape them.

David asked if he should do this himself or if he should hire a professional landscaper, and we of course, encouraged him to DIY it.

The key is to start the process when the branches are small enough to be cut with hand pruners, or loppers, at most. A good, sharp pair of bypass pruning shears is essential, so invest in a good quality pair and keep them in shape.

To train shrubs into trees, you’ll need to do a type of pruning called thinning out, which basically means that you’ll need to remove branches all the way back to their source. The general recommendation is to never remove more than 1/3 of a plant at a time, before allowing it to regrow and recover (normally in a year’s time), and more conservative folks would say no more than 1/4.

If you’d like your crape myrtles to be a single-trunked tree, you’ll need to begin the selection process of which of the current trunks you’d like to keep and which you’ll remove. You’ll want to choose the trunk with the largest diameter, as long as it has no damage that would otherwise inhibit its growth.

When learning to prune, it really helps to see illustrations, and the various cooperative extension systems across the nation have produced some wonderful research-based information that you can download for free. Here’s one good resource for you.