What Happens if You Don't Trim Crape Myrtles?

Natural Growth

• When allowed to grow naturally, crape myrtles are multi-trunked flowering trees with rounded canopies. Unnatural and improper pruning reduces crape myrtles to stubby shrubs with disfiguring knobs at stem ends. New growth results in weak, spindly stems and produces branches that cross. Crossing branches rub together and remove bark, facilitating insect and disease penetration. If you don’t trim crape myrtles, trees develop strong branches and open canopies without displaying disfiguring terminal knobs. Their natural growth form maintains aesthetic and structural integrity.

Flowers

• Prized as a flowering tree, crape myrtles have blooming periods of up to 120 days, according to Floridata.com. Topping, or heading, is a pruning technique that removes all crape myrtle trunks and stems to a uniform height. Topped crape myrtles bloom up to one month later than trees that are left unpruned, according to the University of Florida IFAS Extension. If you do not prune your crape myrtle, your tree will bear more flowers than unpruned trees. Individual blooms may be larger after pruning, but not as prolific.

Tree Health

• Topping crape myrtles compromises plant health by promoting stem decay, depleting food reserves and inhibiting photosynthesis. Exposing multiple trunk and stem areas provides easy access for insects and disease. Virginia Cooperative Extension reports that stem decay is significantly increased in crape myrtles that have been severely pruned or topped. Food reserves stored in branches are severed from trees after severe pruning. Photosynthesis, essential for tree survival, is severely inhibited after removing a plant’s canopy. Without sufficient photosynthetic activity, plants are unable to produce food. Leaving your crape myrtle unpruned promotes plant vigor.

Selective Pruning

• If you choose not to trim your crape myrtle, you may need to make occasional pruning cuts to maintain tree health. Always remove dead or diseased branches by cutting beyond affected areas. Any branches that cross each other should be cut back so that all limbs do not abrade each other. Basal sprouts, or suckers, are more prolific in pruned trees but are also present in untrimmed trees. Pull these while still tender before suckers develop woody stems. With minimal pruning intervention, your crape myrtles will grow stronger and healthier.