The keys to success with crape myrtle trees include adequate sunlight, proper soil pH, good drainage, proper pruning, adequate fertilization, proper mulching and insect control, according to William Tyson, Cooperative Extension coordinator for Effingham County.
Crape myrtles need full sun—eight hours or more of direct sun daily—to thrive and bloom. Gardeners should check the sun patterns in their yards before planting crape myrtles.
Crape myrtles thrive in slightly acidic soils with a pH of about 6 to 6.5. If the pH level is off, the plant will not use fertilizer properly, and the gardener will be left with substandard crape myrtles.
Late winter is the time to prune crape myrtles but gardeners don’t need to prune all of their crape myrtles every year. Some trees may not need to be pruned.
Gardeners should prune the trees so that they maintain a natural shape and to thin out branches and allow light into the canopy. To maximize spring growth and summer bloom, gardeners should fertilize their crape myrtles in early spring just prior to new growth.
Fertilizers like 8-8-8, 10-10-10, 12-4-8 or 16-4-8 will work fine and are ideal for crape myrtles but you shouldn’t go over board. Fertilizers can be applied directly over the mulch. And over fertilizing the trees causes excess growth and reduce the number of blooms on each tree.