How do you prune crepe myrtles (without destroying them)? When do you prune these small trees for a second bloom? In our growing guide, learn more about how to care for the “lilac of the South” to maintain its long blooming period of showy flowers.
About Crepe Myrtles
Crepe myrtles are a group of about fifty species of flowering shrubs and small trees which thrive in USDA Hardiness Zones 6 to 9. They’re within the genus Lagerstroemia, native to China; those planted in the US are typically Lagerstroemia indica or hybrids thereof, and are deciduous.
When botanist to the French King Louis XVI André Michaux introduced this tree into Charleston around 1786, the crepe myrtle quickly became Southern favorite as it’s heat- and drought-resistant (as well as deer-resistant!).
As well as their long-lasting blooms in summer, crepe myrtles offer year-round interest with beautiful foliage in autumn and gorgeous, exfoliating bark in winter. As the tree matures, the bark at the base will begin to peel, leaving behind a unique, smooth trunk.
The showy flowers cover the shrubs in clouds of color from from July through September, adding color when many other flowering trees have finished. Colors range from true reds to vibrant pinks, shades of purple and whites. Blooms are formed in panicles 6 to over 15 inches long.
Coming in many sizes, crepe myrtles can range from sprawling 2 to 3 foot tall shrubs to multi-trunked and single-stemmed trees that reach 25 to 30 feet and 10 to 15 feet wide. It is VERY important that you understand the mature height of your crepe myrtle variety. This is the biggest problem and we all want to avoid what one Southern garden writer calls “crepe myrtle” murder. If you have a smaller space, choose a dwarf or semi-dwarf varieties.
Crepe myrtles also make excellent container plantings, so those of us in colder climates can still enjoy this flowering shrub–as long as you pull your container crepe myrtle indoors for the winter.
Crepe myrtles love full sunshine with a minimum of 6 hours a day. They will grow in partial sun or shade but will likely not flower as much. Planting these trees in a shady location is the most frequent cause of failures to bloom.
They are not picky about their soil as long as it drains well; they do not like a wet, soggy site. In contrast, crepe myrtles are drought-tolerant once established, which is one of the reasons they are low maintenance. Crepe myrtles prefer neutral to slightly acidic soil. If soil gets to alkaline (above 6.5), this may cause yellow leaves; add garden sulfur to lower the pH; coffee grounds can help,too.
Think about proximity to sidewalks, powerlines, and other obstructions. Picking a tree-sized crepe myrtle to plant under your first-floor window might result in a lot of annual pruning in the following years. A crepe myrtle that grows to 25 feet tall and wide might get you in trouble with your electric company if you plant it under the power lines.
Do future you a favor and plant the right shrub in the right location.
When to Plant Crepe Myrtles
In USDA zones 7 to 10, crepe myrtles are best planted in the fall or early spring. However, if you grabbed a crepe myrtle from the nursery or garden center in the summer because it caught your eye in full bloom, don’t worry. They can be planted in summer as well.
Regardless of planting time, keep an eye on it and water it regularly as it becomes established. It will be especially important to give a newly-planted crepe myrtle lots of water in the summer months to promote good root growth. Don’t stick it in that sunny spot in the backyard in August and then go on vacation for three weeks.
Start by giving the tree or shrub a thorough watering while it is still in the original container. Not only will it slip out of its pot more easily, but you’ll also minimize stress on the tree.
Remove the sod (if any) and place it aside to compost later.
Dig a hole as deep as the root ball but about three times as wide. Ideally, the hole should look like a shallow bowl, not a well.
Clip any circling roots, sometimes called girdling roots. If your new crepe myrtle is rootbound, score the outer edges of the rootball to stimulate new growth. Rough it up a little.
Place the plant in the hole. It should be sitting so the old soil level (from when it was potted) will be at the same height when the hole is filled in.
Backfill the hole with the soil you removed, and tamp it in firmly. You don’t want air pockets down by the roots. Pause when the hole is partially refilled and water, then continue backfilling.
Make a ring or wall of soil an inch or two high in a circle around the shrub or tree to help water infiltrate instead of running off, then water again.
Apply mulch 1 to 2 inches deep. Use an acid mulch such as pine bark or oak leaves for crepe myrtles.
Mulch tip: Don’t pile the mulch up around the trunk like a cone. Mulch should not contact the stem of the tree or shrub. Make a donut, not a pyramid.
Crepe myrtles are fairly low-maintenance additions to your garden or yard. Follow these simple tips.
During the first two years, crepe myrtles should be watered regularly and deeply once a week, or twice a week in extremely hot weather. Once established, take care not to over-water these drought-tolerant trees; water about once every other week.
During its first growing season, give the trees a slow-release liquid fertilizer every month from spring to summer; always water in well. After its first growing season, crepe myrtles should only need fertilizer once a year in early spring; do not fertilize in summer.
Remove suckers that grow at the base. They rob energy from the plant and look messy.
Snipping off spent flower clusters produces more blooms.
You’ll notice seedpods after bloom; it’s not necessary to remove seed pods but you may remove the seed pods with a sharp pair of clippers to remove the weight off branches and are also likely to get a second bloom in September.
Apply 1 to 2 inches of pine needle mulch to protect the roots during winter in colder climates.
Crepe myrtles will transplant easily if they are outgrowing their space; transplate when dormant in late fall or winter.
How to Prune a Crepe Myrtle
Crepe Myrtles do not need to be pruned, however, people often end up pruning because they bought a tree that’s too big for their space. Unfortunately, many people prune incorrectly and butcher their tree. Never cut this tree back to thick stubs. Always keep the natural shape of the tree. Here’s how to prune:
In late winter, when the tree is dormant and before leaf-out, prune this multi-trunked tree to 3 to 5 trunks (no more than 7) and remove low-hanging branches below the 4- to 5-foot height of your tree. Prune large branches back to a crotch.
Early each spring, remove dead and weak branches or interior branches that cross, rub, or grow inward.
You may have seen the name spelled crape myrtle, crepe myrtle, crepemyrtle, or crapemyrtle. All are acceptable.
There is no need to buzz off the tops every year like a flat-top haircut. Plant the appropriately-sized crepe myrtle and enjoy its beautiful, natural form.
Note that crepe myrtles may not bloom fully until their second season. Other reasons for lack of bloom include: not enough sun, over-pruning, too much fertilizer or watering.
The main disease problems with crape myrtles are fungal leaf spot and powdery mildew. Look for resistant varieties, especially if you live in a wet, humid location. Many of the issues below can be handled with soapy water sprays, horticultural oil, or neem oil.