Crape Myrtle, or Lagerstroemia indica, to use its botanical name, is in many ways one of the most special landscape trees suitable for a small garden. It has lovely, fresh-green foliage in the spring, in cold climates it sports dramatic fall color, and when out of leaf in the winter, creates an interesting silhouette with its reddish, peeling bark.
Primarily though, the Crape Myrtle is famous for its spectacular blooms that adorn the tree in the summer. If placed strategically, it can be unmatched as a focal point in the garden. It is this emphasis on the flowering properties of Crape Myrtle that leads many landscape professionals to prune it differently from virtually all other landscape trees.
With landscape trees, pruning amounts to the judicious and careful removal of whole limbs, when and where necessary. In principle, it is mistaken to shorten a tree’s branches, as this spoils the natural shape and “flow” of a tree, induces too many new branches to sprout from one point, (the pruning cut), and is liable to adversely affect the long-term health of a tree.
Shortening branches, or pollarding, is the chosen method for pruning flowering shrubs such as roses or lilacs. It is also the suggested way concerning the Crape Myrtle, for the expressed purpose of increasing and improving flower production. The reason for this is that more and superior blooms develop from the juvenile, spring growth that sprouts from a pruning cut.
As a deciduous plant, Crape Myrtle is best pruned in the winter – its dormant season. In Mediterranean and other mild winter climates, it is best to wait until the latter part of the season, while pruning in spring, while the sap is rising in a deciduous plant, can be a serious mistake.
The question arises however, as to whether it is necessarily wise to prune a Crape Myrtle as though it were a rose bush. For regular, persistent pruning, year after year, is likely to weaken the tree, slow-down its vitality, and make it more vulnerable to pests and disease. Therefore, to grow and prune a Crape Myrtle just for its flowers amounts to condemning it to an early demise.
In fact, as previously mentioned, the species has immense aesthetic value as a small-scale ornamental tree, irrespective of its floral display. A reasonable compromise is to alternate between pruning some branches in one year, and others in the years that follow. In addition, it’s a good idea to allow some of the stems that sucker from the base of the plant, to develop into trunks, which can later replace older, worn-out stems. In any case, the Crape Myrtle looks better as a multi-stemmed tree, than as a single-stemmed one.