Photos by Gary Knox
February 21, 2014
By Gary Knox
This is the time of year when we often see crapemyrtles unnecessarily topped: main stems that are several years old are cut back, usually leaving branch stubs 2 – 5 inches or more in diameter. Topping is sometimes called heading, stubbing, rounding and dehorning.
In the case of crapemyrtles, another name for this practice is “crape murder”. Topping a crapemyrtle is almost always unnecessary. Because people have seen this done in previous years, home owners often mimic this practice in their own yards, not realizing the unfortunate consequences.
Topping reduces flower power and plant health. Research at the University of Florida (http://edis.ifas.ufl.edu/ep399) found that topping crapemyrtle (“crape murder”) delays flowering up to one month. In other words, unpruned trees may begin flowering in June whereas topped trees don’t flower until July. This research also found topping reduced the number of flowers and shortened the flowering season. Finally, topping stimulated more summer sprouting from roots and stems. Sprouting results in greater maintenance since sprouts are usually removed to maintain an attractive plant appearance.
Crape murder (topping) is detrimental to plant health. Topping removes large amounts of food reserves stored within branches because large-diameter stems are removed. By dramatically reducing plant size, topping decreases the plant’s ability to produce food (starches) through photosynthesis. The large branch stubs caused by topping result in large areas of exposed wood that allow access by insects and wood-rotting organisms, weakening the plant’s structure. Finally, topping results in many dead stubs throughout the tree.
Don’t fight it, replace it. Unfortunately, landscape professionals and home owners often must maintain crapemyrtles that others planted, and so must deal with the consequences of poor cultivar selection and/or placement. If a crapemyrtle requires routine pruning to fit into its surroundings, it should be replaced with a smaller maturing cultivar. Dwarf crapemyrtles mature at a height of 5 feet; medium crapemyrtle cultivars grow up to about 15 feet in height, and tall or tree-size crapemyrtle cultivars exceed 15 feet and often grow to 20 – 30 feet tall in 10 years.
Some of the best tree-size crapemyrtle types include Red Rocket® (true red flowers), ‘Sioux’ (pink), ‘Osage’ (pink), ‘Apalachee’ (lavender) and the familiar ‘Natchez’ (white). Medium crapemyrtles (up to about 15 feet tall) are perfect as patio trees. Good cultivars of medium crapemyrtles include ‘Hopi’ (pink flowers), ‘Acoma’ (white) and ‘Catawba’ (purple). Some newer crapemyrtles have burgundy-colored leaves all summer long. Most of these will be medium size, but they are too new to know for sure. For burgundy-leaved selections, look for plants with names that include Black Diamond™, Delta Jazz®, Ebony and Magic™; they come in various flower colors. Finally, dwarf crapemyrtles are harder to find, but plants in the Dazzle® series are often available and come in various flower colors.
Right plant, right place. Best locations for crapemyrtle are areas in full sun with plenty of room for the cultivar size and away from walkways and roads. Proper selection of crapemyrtle cultivar and proper placement in the landscape can result in a low maintenance crapemyrtle without the need for significant pruning.
For more information, see ENH1138, Crapemyrtle Pruning, at http://edis.ifas.ufl.edu/ep399.
Dr. Gary Knox is an Extension Specialist and Professor of Environmental Horticulture with the University of Florida at the North Florida Research and Education Center in Quincy. For more information about gardening in our area, visit the UF/ IFAS Leon County Extension website at http://leon.ifas.ufl.edu. For gardening questions, email us at Ask-A-Mastergardener@leoncountyfl.gov
Watch on WFSU’s TV show Dimensions, Gary Knox and Stan Rosenthal UF/Leon County Extension Forester tell more about crapemyrtles.