Lagerstroemia, known as crepe myrtle or crape myrtle is a tree that thrives in US Hardiness zones 7 through 10, making it a perfect choice for your Alpharetta or Roswell yard. The genus came to the US over 200 years ago and got its name from the Swedish merchant Magnus von Lagerstrom.
The most popular species is L. indica. It is a native of southern China and Thailand. For centuries, crepe myrtles have been grown in Asia as ornamentals.
Of all the southern trees and plants, crepe myrtles are among the most desired for their outstanding summer display of blooms and their brilliant fall colors. 72 Tree, Seed & Land Co. prepared an extensive article covering the characteristics, environment, and care these trees need to flourish and light up your landscape.
The Lagerstroemia genus contains approximately 50 species of trees and shrubs both deciduous and evergreen. So, this species can indeed grow as a tree or shrub, making it ideal for hedges, container planting, or even in groupings along your landscape.
Height – The L. indica species possesses cultivars and hybrids that remain under 5ft in height, some that reach 11 to 15ft in height, and those that tower over the others, reaching heights of 20 to 30ft.
Canopy – At maturity, the canopy can reach from 6ft to well beyond 15ft depending on the species.
Trunk – Crape Myrtles are known to have multiple trunks with beautiful bark which exfoliates in the winter months. Be cautious when pruning or working around these trees, their wood is somewhat brittle, and the trunks may easily crack when put under pressure.
Lifespan – When planted in full sun and fertile soil, Crepe Myrtles can live well beyond 50 years. In fact, dotted along the southeastern landscape, it is common to come across specimens over 100 years old.
Uses – Depending on the species, these trees work as shrubs, hedges, container plants, landscape groupings, and in some cities as street trees.
If you decided you prefer to plant an evergreen instead, visit 72tree.com/3-evergreen-species-alpharetta-roswell-yard/ for some great candidates.
About two years after planting, these species become very tolerant to drought, heat, humidity, and will do well in nearly any well-drained soil. They become robust enough to resprout even after being completely frozen.
Crepe myrtles are low maintenance. However, you still need to do some planning before planting and a bit of upkeep as they grow.
Planting – Location is critical when planting crepe myrtles. Select a spot that has well-drained soil and gets full sun. Planting in partial or full shade will significantly reduce its ability to flower and may reduce its lifespan as well.
Crepe myrtles have a shallow and very fibrous root system which can extend 3 to 4 times the diameter of the canopy. As with all trees, the planting location should be at least 5 to 10 feet away from cement pathways, foundations, and sidewalks.
Pruning – Very little pruning is required. Improper pruning disrupts the development of a robust branching system and will leave your specimen deformed and vulnerable to weather, pests, and fungi.
If there is a need to prune, it should occur in late winter or early spring to correct the following:
• Removing crossed or rubbing branches.
• Removing suckers from the base.
• Branches growing inward (toward the center).
• Canopy thinning for better air circulation.
• Gradually remove side branches up to 4 or 5 feet as the tree grows.
• Reducing multi-trunk trees to a single trunk (not recommended).
Summer pruning can include:
• Removing old seed pods and spent flowers (removing them after the first bloom encourages further blooming).
• Removing small twig-like growth.
All crepe myrtle species bloom on new wood. The proper and minimal pruning of your tree will encourage this growth and promote a beautiful summer blooming season.
If you are pruning your tree because it has gotten too large for its location, you’ve planted the wrong species.
Watering – Provide newly planted crepe myrtles with a deep and thorough watering. Then, water your tree up to 4 or 5 times per week during hot weather or when planted in sandy soil. When the tree is dormant or during cold weather, your tree will need watering once per week.
Blooms – As previously mentioned, all crepe myrtles bloom on new wood. After the first bloom, removing the spent flowers will encourage further blooming in the season.
These trees like all others on your landscape are susceptible to infestations, disease, and animal damage. The best defense against these threats is to keep your tree(s) healthy, plant, prune, and water them properly and they will be less likely to suffer damage from the following:
Pests that infest crepe myrtles:
Japanese Beetle – This insect is approximately 1/2 inch in length, its body is oval and metallic green, and its wings are copper in color.
Larvae remain underground where they consume grass and young tree roots. Adult beetles feed on the tissues of the leaves and are most active on trees in full sun during the warmest part of the day.
A Japanese beetle infestation can cause severe damage to all of the trees on your landscape. Traps, pyrethrins, and neem oil can help curtail a beetle outbreak. However, this is an urgent situation which needs to be evaluated by a certified arborist.
Crape Myrtle Aphid – These insects are yellowish-green and have black spots on their abdomen. They measure from a sixteenth to an eighth of an inch in length.
Both nymphs and adults feed on the underside of the foliage causing it to droop and yellow leaf spots to appear. Buds, flowers, and branch tips can all be damaged as well from their feeding.
Sooty mold will appear on the leaves when there is an aphid infestation. This mold is a byproduct of the aphid’s excrement and will disappear once the outbreak ends.
Watch this video to learn how to eliminate aphids and “black” sooty mold on your crape myrtle.
When a crape myrtle aphid infestation occurs, apply a 2oz. to 1 gallon solution of molasses and water to the affected areas and release ladybugs around the tree. Neem oil is also very useful in controlling aphids.
Fungi that attack crepe myrtles:
Powdery Mildew – This fungus appears as a white powdery substance and can spread very quickly if not handled properly.
It is worth noting that trees planted in full sun are not typically bothered by this fungus.
To control powdery mildew, spray a fungicide on the affected area and its surroundings.
Sooty Mold – This mold has a tar-like appearance and is a result an aphid infestation (see above).
Bark Shedding – Don’t be alarmed. While it may seem that something has infected your tree, there is nothing wrong with it. Crepe myrtles, once reaching adulthood will naturally exfoliate their bark in winter months, revealing the magnificent color variations of its trunk.
If you are looking for an incredible addition to your Alpharetta yard or landscape, crepe myrtles are a must have. Besides being low maintenance, they will put on a colorful show every summer.
An added plus in the summer is when the blooms attract birds seeking refuge and nesting and offer their nectar and pollen to the bees.