Question
I live in Vacaville, California between San Francisco and Sacramento and have a Crepe Myrtle of unknown age, but over 20 years old.  It used to be a normal tree but lately two things have been occurring that make me write to you.  It now blooms only every other year and not much when it does.  It also drops its bark.  Other than that it looks very nice and is a lovely tree.  Pieces of bark peel away and fall to the ground.  What do these two symptoms tell you and what should I be doing to maintain the health of the tree?

Answer
The peeling of the bark of Crept Myrtle is normal and nothing to worry about. Too things that slow crept myrtle from blooming--not enough sunlight and the need for fertilizer, Not much you can do about the sunlight beyond moving the tree and this may cause more damage than it is worth. You can prune any dead branches this will allow light to get in the foliage. After the tree blooms prune off the old flower heads this encourages more flowers.I would fertilize the tree with 10-10-10 fertilizer at the rate of 1 lb of fertilizer per inch of trunk diameter scattered around the tree and watered in good. Fertilize just before a rain storm and you will not need to water.