Winter is almost here and time to dormant prune ornamentals, roses and fruit trees. I am disturbed to see how some people despoil crepe myrtles (Lagerstroemia indica) when they prune them. The pruning technique used is called pollarding and it is defined as a tree cut back nearly to the trunk, so as to produce a dense mass of branches. Perhaps Wikipedia says it best about pollarding crepe myrtles “This is not a practice to use if one wants an attractive, healthy natural tree as the natural growth is stunted. Many times this is done in southern states of the USA to crepe myrtles, and is called “crepe murder” by some.” I can testify that I have seen crepe murder in our county.
Actually, crepe myrtles are better left unpruned than murdered. They will produce fewer blooms as there is less new growth which encourages blooms, but they are much more attractive with the natural look. Part of the charm of crepe myrtles is the bark, so leaving lots of the tree structure to display its colorful, peeling bark is so much better than pollarding it. Leaves are a gorgeous crimson each fall providing another esthetic feature.
Because crepe myrtles bloom on new wood, pruning does encourage new growth and that is why they are often pollarded to provide new growth. However, there are more esthetic and healthier ways to assure this. I came up with my own method years ago and two years ago while visiting the UC Davis campus, I saw that others too had used the same approach to pruning crepe myrtles.
I train crepe myrtles like a fruit tree with an open center as seen in the photograph. This openness allows sunlight and air into the center, reducing diseases such as powdery mildew and promotes new growth for blooms. A heading cut on a young tree at about 3 to 4 feet will create branches to be trained to an open vase. There is a tendency for the crepe myrtle to have multiple trunks, but I prefer to select one main trunk and work with it. However, you can create an open vase tree with multiple trunks from the ground, especially if you start to work with a tree established in this manner: see http://www.finegardening.com/pruning-crape-myrtles. Select no more than 3 to 5 well-spaced trunks and prune out the rest. Crepe myrtles often send up suckers near the base which should also be removed.
After selecting a single trunk, it is a matter of making choices of which of the new shoots will be selected to create the vase shape of the tree. Select no more than 3-5 main scaffold branches. I usually head these at 2-4 feet or so to encourage branching. These branches in turn can be headed at 2-3 feet the following year to produce secondary scaffolds. At some point when the tree is shaped and at a sufficient height, I truncate the new shoots to a two bud spur. The choice is often for spurs which will keep the tree opening up. Pay attention always to which way the buds are facing on your two-bud spur selection as well as scaffold selections. Buds are usually located opposite each other in alternating sets, i.e., the next set is 90 degrees from first, so in some cases leaving 4 buds will provide the best directions for the shoots because the top buds will usually dominate. Last year’s two-bud spur may produce two or three shoots, so you will need to reduce this to one to select the next two-bud spur.
You can keep the tree at whatever height you want. By selecting two bud spurs on each branch each year, you will only add about a foot to the tree in 6-8 years. If you want to shorten the tree you can cut back into old wood and the tree will push some vestigial buds and continue to bloom. Thus this method allows you to keep the tree at a reasonable height. I need a ladder to prune my trees, but you could keep the tree shorter if desired and staying off ladders is always safer.
Prune weak side growth to strengthen it and induce more vigor. This will help provide blooms in places other than at the top. More evenly distributed blooms are more appealing. Crepe myrtles come in a range of sizes and colors to suit your landscape needs. They do well in California and are drought tolerant as well as beautiful. Cheers to better pruning and enjoyment of crepe myrtles.