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How To Grow And Care For Crepe Myrtle

4 de desember de 2022

We Southerners share certain memories—the smell of a freshly mowed lawn, the high-pitched cry of cicadas on sweltering days, the juicy taste of sweet watermelon, and the vision of huge crepe myrtles bent low by the weight of their blooms.

Although native to China, crepe myrtles have set deep roots in our Southern soil, becoming a part of both our landscape and our traditions. The vaunted crepe myrtle (Lagerstroemia indica) arrived in England from its native China in 1759. It impressed very few people, though, because it refused to bloom. England just wasn’t hot enough. 

However, the American South was. So when plant explorer and botanist to King Louis XVI André Michaux introduced this tree into Charleston around 1786, it celebrated like an innocent prisoner released from jail and has thrived in the South ever since, quickly becoming a Southern favorite.

And why not? These easy-to-grow trees possess many outstanding features. Sinewy and strong, crepe myrtles have gray, tan, or cinnamon-hued branches that bear glorious clouds of colorful, long-lasting blooms starting in June. In the fall, they dependably produce radiant foliage in reds, oranges, and yellows. Long, cool autumns yield the best leaf display; sudden frosts following warm, humid fall weather often freeze leaves while they’re still green, ruining the show. Winter reveals their exfoliating bark, which makes their naturally sculpted trunks look like living works of art.

Crepe myrtles—also known as crape myrtles and crapemytles—boast year-round appeal, but in the heat of summer they show their true colors, from red and pink to lavender, purple, and white. Widely available, they can be found at most any nursery or garden center, and this is a great time to purchase them because you can see exactly what color you’re getting. Just remember that if you plant them in summer months, you’ll need to give them lots of water to help them adjust to the garden and promote new root growth.

Plant Attributes

  • Common Name: Crepe Myrtle
  • Botanical Name: Lagerstroemia indica
  • Family: Lythraceae
  • Plant Type: Shrub, Trees
  • Mature Size: Sizes range from 3’ to 30’ depending on the variety.
  • Sun Exposure: Full sun
  • Soil Type: Loamy, clay, well drained soil. Crepe myrtles can tolerate most soil conditions with good drainage.
  • Soil pH: Acidic to Slightly Alkaline Soil (5.0-7.0)
  • Bloom Time: Summer, Fall
  • Flower Color: Red, Pink, White
  • Hardiness Zones: USDA 6-9
  • Native Area: Asia

Crepe Myrtle Care

Crepe myrtles are low-maintenance trees that thrive with very little fuss if given the basics: sun, water and a light trim now and again. 

Light

Crepe myrtles thrive in full sunlight, so your planting location should receive sunlight the majority of the day but also have enough room for the tree to grow to its intended height properly. Shaded areas will likely result in crepe myrtles not blooming, and partial sunlight will yield poor results. Leave enough horizontal space for the crepe myrtle’s roots to expand, but be aware of the varieties» maximum height because porch ceilings or other overhanging elements could prevent its proper growth. It’s best to have an unobstructed space, such as a driveway or fence line, to plant these trees because it receives sunlight while not competing for space.

Soil

Crepe myrtles grow best partly acidic soil. Check with your local extension agent about getting your soil sample tested to determine the ph of your soil. Home testing kits and soil testing tools are also available but may not offer the followup steps needed to amend soil that the extension services provide. If soil ph is over 6.5, garden sulfur is the best option for lowering the ph. Be sure to read the application instructions because too much garden sulfur can be detrimental. Water soluble acidic fertilizers can be applied in the spring each year. If you are a coffee drinker, regularly sprinkle coffee grinds around the base of your crepe myrtle trees to slowly lower the ph of the soil. This soil should be well-draining.

Water

The best recipe for crepe myrtle success is to start with wet soil and water consistently throughout the first year of the growing season to prevent air pockets or to dry out the roots. After initial growth, you don’t want to over-water these plants, which can be reasonably drought-resistant, as long as it sees water about once every other week.

Temperature and Humidity

Crepe myrtles may suffer from cold damage in cooler climates, so if you live in the Upper South, be sure to plant cold-hardy selections such as «Acoma,» «Centennial Spirit,» or «Hopi.» If you live in areas that are consistently wet and humid from midsummer to fall, plant varieties that are found to be more resistant to the leaf spot damage caused by the fungus Cercospora lythracearum such as ‘Tonto’, ‘Catawba’, ‘Sioux’, or ‘Tuskegee’.

Fertilizer

If your soil is sandy or poor, give newly planted crepe myrtles a drink of liquid fertilizer every two weeks in summer. After its first growing season, crepe myrtles should only need fertilizer once a year—usually in spring before new growth begins.

Mulching

Use an acid mulch such as pine bark or oak leaves for support. 

Pruning

Crepe myrtles bloom on new growth and should be pruned in late winter or early spring. Dwarf and short types need only minor, cosmetic pruning. On medium and tall types, prune to a tree form. Remove suckers at the base, twiggy growth, crossing branches, and branches growing toward the center of the plant. Also gradually remove side branches on main trunks up to a height of 45 feet The tree should be open enough that a bird could fly through unimpeded. This exposes the handsome bark and also improves air circulation, making leaf diseases such as mildew and leaf spot less likely.

When pruning a crepe myrtle, don’t chop your large crepe myrtles down to ugly stubs each spring just because your neighbors do. This practice—often called “crepe murder”—ruins the natural form and encourages the growth of spindly, whiplike branches too weak to hold up the flowers. To reduce a crepe myrtle’s height, use hand pruners or loppers to shorten the topmost branches by 2-3 feet in late winter, always cutting back to a side branch or bud. For branches more than 2 inches thick, always cut back to the crotch or trunk. Don’t leave big, ugly stubs.

During the growing season, clip off spent flowers to promote a second, lighter bloom. Also, prune dwarf forms periodically throughout the growing season, removing spent blossoms and thinning out small, twiggy growth.

Transplanting

If you’ve already planted a crepe myrtle that’s overgrowing its boundary, you might want to move it. These trees may be easily transplanted, and only a small root ball is needed for success. It’s best to move them in late fall or winter, when they’re leafless and dormant. See our guide to planting crepe myrtles for step-by-step planting directions.

Overwintering

Crepe myrtles need little overwintering care. A light 1-2 inches mulch layer of pine fines or pine straw can help to hold moisture around the roots during drier winter months. Make sure the mulch is not mounded around the base of the tree and that a gap is left around the trunk for air circulation.

How to Get Crepe Myrtles to Bloom

One of the crepe myrtles best attributes are its blooms. Audacious spikes of pink, purple, white, and red flowers crown its sculptural branches for months in summer. Unlike spring’s cherry trees, with delicate flowers that may last only a week or two, crepe myrtles can bloom all summer. Light tip pruning or snipping off old blooms will encourage more flowers.

Once crepe myrtles have bloomed and shed their first flowers, they will set seed. The small round seed pods or capsules usually weigh the limbs down, making them sag. Removing the seeds takes off the weight and the branches rise up. Plus, if you remove the seed pods early enough in the year—say late July—you’ll probably get a second flush of blooms in September. 

Using a sharp pair of clippers, cut off the seedpods. New shoots with buds will quickly appear, and you will get a second bloom. If the temperatures stay warm into the fall and you continue to remove spent flowers, you may get a third or fourth.

Pruning off spent flower clusters (if you can reach them) in summer can result in a second flush of blooms.

Popular Types of Crepe Myrtles

Most crepe myrtle trees planted today are selections of Lagerstroemia indica or hybrids between this species and Lagerstroemia faurei. New selections pop up all the time. One thing we’ve learned over the past two decades is that the mature size of many selections, particularly those named for tribes of Native Americans, such as «Natchez,» grow bigger than first advertised. When planted in small yards or near the house, they may quickly outgrow their welcome, resulting in a winter-spring pruning ritual known as crepe murder, in which innocent trees are chopped back into ugly, knuckled trunks.

Crepe myrtle (L. indica)

This is the premier summer-flowering tree of the South. It tolerates heat and drought and does well in most soils as long as they are well-drained. They may freeze to the ground during severe winters in the Upper South, but will re-sprout. Gardeners there should plant cold-hardy selections such as «Acoma,» «Centennial Spirit,» and «Hopi.» 

This variety is variable in size (some forms are dwarf shrubs, others large shrubs or small trees) and habit (spreading or upright). Dark green leaves are 1 to 3 inches long and turn yellow, orange, or red in fall. Crinkled, crepe-papery, 1- to 1 1/2-inch wide flowers in white or shades of pink, red, or purple are carried in dense clusters. The tree has an attractive trunk pattern: Smooth gray or light brown bark peels off to reveal reddish brown inner bark.

Japanese Crepe Myrtle (L. fauriei)

Native to Japan, these trees grow 20 to 30 feet tall and wide, with upright trunks and outward-arching branches. The leaves are green and grow to have blades as long as 4 inches. These trees also have especially handsome bark: The smooth gray outer bark flakes away to reveal glossy cinnamon-brown bark beneath. Small white flowers bloom in the summer. 

Japanese crepe myrtles are also resistant to mildew and best known as a parent of hardy, mildew-resistant hybrids with L. indica. Meanwhile, the plant variety «Fantasy» has even showier white flowers, and «Kiowa» has outstanding cinnamon-colored bark.

Queen’s Crepe Myrtle (L. speciosa)

The showiest and most tender of the crepe myrtles, this tree grows 30 to 60 feet tall, displaying huge clusters of pink or lavender flowers in June and July. Individual blossoms reach 2 inches long. Leaves reach 4 to 12 inches long and turn red in fall. The tree has smooth and mottled bark. It is a fast grower and annual pruning in winter is especially important to control size and form.

Propagating Crepe Myrtle

Crepe myrtle can be grown from both clippings of a mature tree as well as by seed assuming you aren’t starting with a patented plant. Because growers spend significant time and money breeding specific plant cultivars they often patent these plants, and replicating those plants is technically a violation of that patent, even if you’re propagating for personal use. You can determine if your crepe myrtle is protected by checking the label. Tags on patented plants will typically have PP for “plant patent” or PPAF for “plant patent applied for” followed by a series of numbers. 

If you know your crepe myrtle isn’t patented, go ahead and create more beautiful blooming babies! See our guide to growing crepe myrtles from clippings and seeds.

Common Pests & Plant Diseases 

​​Occasionally aphids, a sap-sucking insect, attack plants but can be controlled through insecticides or a soap and water solution for a less harsh preventative. For more on aphid control as well as how to handle the associated issue of sooty mold, see our guide to common crepe myrtle problems.

Another complication occurs to trees planted in a shady area with damp or humid growing conditions. Powdery mildew is a fungus that grows on leaves, preventing new growth and damaging leaves.

Fortunately, crepe myrtles tend to be deer resistant so you won’t have to worry about them munching on tree leaves.

Guidance from Grumpy

If your crepe myrtle is dropping leaves, chances are your trees are infested with a fungus called Cercospora leaf spot. Mine have had the same problem in the past. Unfortunately, while breeders have produced many crepe selections resistant to powdery mildew, they haven’t given us many that resist this leaf spot. And because the fungus spores are easily transmitted from tree to tree with the wind and more crepe myrtles are being planted every day, the problem will probably get worse. The good news is that this leaf spot doesn’t seem to really hurt an infected tree, even if it drops all of its leaves prematurely. It still blooms the same. Keep leaf spot from showing up next year by raking up all the fallen crepe myrtle leaves and throwing them out with the trash. Then next summer, spray the tree with a fungicide called Immunox, which can be found at most garden centers. —Steve Bender

— Guidance from Grumpy