Pruning a crepe myrtle
I have a Muskogee Crepe Myrtle that is 2 years old. It is now probably 12 feet and has some very long branches. From what a I read about pruning, branches should only be cut where they attach to another branch, and not in the middle of a branch. These long branches are fairly thin. How and when should I prune this crepe myrtle? What type of fertilizer should I use?
'Muskogee' Crapemyrtle is a U.S. National Arboretum introduction that wants to grow into a tree or shrub that is 30 feet tall. In some areas of central Maryland (I am in western Howard) they get killed back to the ground each year in the last several winters.
That is o.k. in that they re-grow and bloom on new wood, but it makes it difficult to say how to best prune and train them.
Either way, now is not a good time to do it.
Since they are one of the last plants to leaf out in the spring, we'd recommend waiting until then to see what is still alive. Prune out any dead branches, and then, depending on whether you are hoping for a tree shape or a shrub/bush (which is easier) remove some of the branches, either all the way to the ground or to the place where they attach to the next main limb.
Here is a page from Missouri about them : http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=265240 You can aim to have about 3-6 well-spaced limbs left growing if the plants don't winter kill to the ground each year.
These trees are often 'limbed up' with age, meaning that lower limbs are made visible by cutting off any lower growth so that the attractive bark is allowed to show, increasing their seasons of interest.
Here is our pruning information: https://www.extension.umd.edu/hgic/topics/pruning