Taxonomy and origin
Crape myrtle is a deciduous shrub or small tree in the genus Lagerstroemia, a group of 49 species in the loosestrife family whose members flower from summer into fall. The species behind the common name is Lagerstroemia indica. It is not a myrtle in any botanical sense: the common name points at the crepe-papery flower clusters and at foliage and bark that resemble true myrtle, and it says nothing about kinship. Crepe myrtle, spelled with an e, is the same plant, and both spellings run side by side on plant tags, in nursery catalogs and in gardening books. The genus honors Magnus von Lagerstroem, an 18th-century Swedish botanist and a friend of Linnaeus. Older references and some tags still carry the name Lagerstroemia chinensis for the common species, a synonym it has since shed.
Two native ranges are published for the species: Asia and northern Australia in one, the Himalayas through southern China, southeast Asia and Japan in the other. What happened after it reached America is better documented. Crape myrtle was introduced into the United States in the early 19th century and gained its popularity in the southern states on the strength of its tolerance for a warm climate, and it has been in cultivation here for more than 175 years. It collected a second common name along the way, Lilac of the South. The size range is the part buyers underestimate. Cultivars run from 3-foot shrubs to 30-foot trees, so the same two words on a nursery tag can describe a plant for the front of a bed or a tree that will reach the second-story gutters, and a large share of the trouble people have with crape myrtle begins with that choice.
A large share of the cultivars sold today came out of one breeding program. Crosses between Lagerstroemia indica and L. fauriei made at the U.S. National Arboretum in Washington, D.C. produced a line of hybrids resistant to powdery mildew, selected at the same time for greater cold hardiness. Every one of them was given the name of a Native American tribe, and 'Natchez' itself was officially named in 1978. The convention is useful at a garden center. Powdery mildew is the disease that spoils flower buds on older varieties, and a tribal name on the tag is a fast first filter for a plant bred to resist it.
Bloom time
Crape myrtle flowers in summer, and across most of its range the show runs from July into September. In the Deep South the first panicles can open as early as May, and at the northern limits of the range flowering carries into fall. The window is written two ways, late spring to summer in zones 9 and 10 and summer elsewhere, or a flat July to September. The flowers arrive in cone-shaped clusters 6 to 12 inches long at the tips of the branches, each one built from small crinkled petals that look like crepe paper. What sits inside a cluster is easy to underestimate: a single 'Natchez' panicle carries 100 to 800 flowers.
The timing runs off new growth. Flower buds form on the current season's shoots, so once spring growth starts, the buds for that summer begin forming on it. That is the reason pruning waits for the end of winter. Whether cutting off faded flowers buys a second round is genuinely unsettled. Removing spent blossoms after they fade stimulates new growth and another flush of bloom in late summer on some cultivars, though a second bloom is hard to force on any cultivar that blooms after mid-July. Pruning research points the other way: tip pruning to take off dormant seed capsules does not induce sprouting and does not reduce flowering, and capsules left on through winter have no effect on the following season's bloom. Left alone, the seedheads are an attractive feature, and they drop on their own as new growth pushes in spring. What holds the seed is a brown six-valved capsule about half an inch wide that splits open at maturity and releases disc-shaped winged seeds three-eighths of an inch across.
Pruning, and what crape murder costs
Prune a crape myrtle in the dormant season, from late winter into early spring, before growth resumes for the year, and keep the job small. Start with the three D's, dead, dying and diseased wood, then take out crossing branches even where they are not yet touching, since rubbing opens wounds that let in disease and insects. On a plant being grown as a tree, a workable order is suckers at the base first, then the lower branches on the bottom third to expose the character of the trunks, then crowded or crossing branches inside the canopy. The lightest version of the job has a name: tipping, also called rounding over or pencil pruning, makes cuts through outer-canopy stems about one year old and roughly the diameter of a pencil. Much of the time even that is optional. A crape myrtle planted in full sun, away from walkways and roads, with room to grow, may need little or no pruning at all.
Topping is the other end of the scale. It is the drastic removal of large-diameter wood, typically several years old, that shortens every stem and branch, and it travels under the names heading, stubbing, rounding and dehorning. Done as a routine, leaving large branch and stem stubs behind, it is the practice known as crape murder. The classic pattern is a cut at one position the first year, a higher position the second, higher again the third, then a fourth-year cut below the original position, and the sequence starts over. Research at the University of Florida measured what that does to the flowers: topping and pollarding delay bloom by up to a month compared with unpruned plants and shorten the bloom season on some cultivars, while tip pruning changes neither the timing nor the duration. The structural cost is worse. Long sprouts break out just below the big cuts and grow into upright unbranched stems that bend under their own weight, and are not strong enough to hold summer flowers, so the branches sag under the blooms. Topping also strips out large amounts of stored starch and leaves wide wounds open to insects and wood-rotting organisms, along with a crown full of dead stubs, and hard cutting drives suckering, which can carry powdery mildew up from the suckers into the canopy and draws aphids to the soft new growth.
A tree that has already been topped can be rebuilt, and the plant supplies the material: hard pruning stimulates sprouting from the roots, the upper stems and the base of the main stems. The rebuild is a selection job. Choose three to five radially spaced shoots that lean slightly outward and let those become the main trunks, then over the following seasons clear the side branches partway up so the canopy starts 3 to 4 feet above the ground. Where a plant truly has to be held below its natural size, pollarding is the controlled version of the same cut: the first cuts go through branches up to about three years old, and every year after that the sprouts are removed back to that original cut. It produces fewer dead branch stubs and less internal wood decay than topping, which is why size reduction is best done that way. A crape myrtle that needs routine pruning to fit its surroundings should be considered for replacement with a smaller-maturing cultivar, and a dwarf or semi-dwarf sized to the spot ends the annual fight with a vigorous cultivar in too small a space.
When to cut, month by month
The pruning year sorts into five windows, and only two of them hold a saw.
Why a crape myrtle will not bloom
Lack of sunlight and lack of moisture are the common causes of poor growth and flowering in crape myrtle. Feeding is the second cause, and it is the one gardeners create themselves. Overly fertile soil produces lush foliage at the expense of flowering, along with somewhat greater susceptibility to winter injury, and heavy nitrogen makes the plant flower less while pushing shoot and leaf growth that winter can damage.
Pruning, pests and cold account for most of the rest. The number of flowers falls as pruning severity rises, measured by the diameter of the cut, so a plant cut back hard carries fewer panicles even in a good year. Bark scale reaches the same result by another route: a heavily infested tree turns black with sooty mold and produces fewer and smaller blooms. Powdery mildew works on the buds directly, and heavily infected flowers may fail to open at all, while infected parts of the plant become distorted and stunted. Cold is the cause people misread most often. Where winter kills the top growth, the roots send up new stems, and those stems flower, because the flowers appear on the new wood, so a plant that looked finished in April can still carry a full crop of panicles the same summer.
Finding the reason it stopped blooming
A crape myrtle that has quit flowering almost always shows the reason from the ground, and the cheapest checks come first.
Black bark, sooty mold, and bark scale
The black crust on a crape myrtle trunk is sooty mold, and underneath it, most of the time, is crape myrtle bark scale. The insect is a felt scale, Eriococcus lagerstroemiae; the adult female builds a white felt sac around herself and lays roughly 100 to 300 pink eggs inside it. She is about one-tenth of an inch long under that soft off-white felt, so an infestation reads from a few feet away as white specks and gray crusting along the twigs and trunk. The nymphs pour out honeydew, and the mold that grows on it accumulates on leaves, twigs and trunks and spreads onto low plants, grass and mulch under the tree. The mold itself is a fungus living on honeydew from sap-sucking insects such as aphids, scales, mealybugs and whiteflies, and it is relatively harmless, since it does not attack the plant directly. The scale is the damaging half: with few natural enemies in this country it builds to numbers that leave branches and twigs completely encrusted, and no crape myrtle variety yet carries a high level of resistance to it.
The pest is new to the country and still moving. It was first detected in the United States in Texas in 2004 and first found in Mississippi in spring 2015. Early reports came from the Dallas and Fort Worth area, and by 2013 it had been reported in Arkansas, Louisiana and the Memphis area of Tennessee. Discovery dates in circulation differ by state: 2004 for the first detection in the country, 2019 for the discovery in South Carolina. It is now well established in more than 20 Mississippi counties and is expected to keep spreading. It does not fly, since only the males have wings; long-range movement happens when people move infested plants, and once it is in an area it travels tree to tree even where the trees stand hundreds of feet apart. In the Southeast it completes two to four generations a year and can overwinter in any life stage, most often as nymphs. Crape myrtle is its main host here, though infestations have also been detected on American beautyberry.
Treatment is a matter of timing. Soil-applied systemic insecticides are the most effective treatments available and the easiest to apply, with active ingredients including imidacloprid, imidacloprid plus clothianidin, dinotefuran and thiamethoxam, and the window that matters is the early part of the growing season, late March through May, which targets the first generation of nymphs. One soil application per year is the limit, and a tree that had scale should be treated again the following year even if spring shows no sign of it. Soil applications carry lower risk to pollinators than foliar sprays of the same neonicotinoids, and a tree treated through the soil should not then get a foliar spray containing one of those products. Dormant horticultural oil after leaf drop in fall, or before bud break in spring, takes out exposed crawlers and nymphs, though oil alone will not control an infestation. Scrubbing trunks and lower limbs with a soft-bristle brush, water and a little dish washing liquid lifts heavy accumulations of scale and mold and restores the look of the bark, but it is not a method of control. Lady beetles do eat the scale, among them the multicolored Asian lady beetle, the twice-stabbed lady beetle and Hyperaspis species, though their numbers lag behind the pest's. Controlling the insects is what controls the mold.
Black on the bark: which one is it
Four different things darken or patch crape myrtle bark, and they take four different responses. One tell separates each of them.
What actually goes wrong, ranked
Thirty-four homeowner threads sampled across garden forums, lawn-care boards, and extension question pages produced the counts here. Two entries carry no count: they come from the extension pest sheets, which put them near the top of what goes wrong.
Nine of the thirty-four threads. Symptoms: knuckled stubs, then a mop of whippy shoots, weak and poorly attached where they meet the old cut. Management: rebuild from the sprouts the stubs throw, one dormant season at a time, and stop cutting at that height.
Seven threads. Symptoms: black film on the bark and leaves. Management: a first insecticide application around May 1 heads off the mold, and a root-zone drench of imidacloprid can take a month to move from the roots into the leaves, so it goes on early.
Five threads. Symptoms: a healthy canopy carrying few or no panicles, often on a plant that flowered for years. Management: sun, competition, and feeding come first, pruning history next, and the twigs get checked for scale last.
Symptoms: white coating on flower buds and young shoots, worst in shady, damp, crowded spots with poor air circulation, where the fungus Erysiphe lagerstroemiae runs. Management: skip the susceptible old cultivars, among them 'Carolina Beauty', 'Wonderful White', 'Raspberry Sundae', and 'Potomac'. A severe case takes a fungicide with myclobutanil, propiconazole, thiophanate-methyl, or copper, often applied more than once.
Symptoms: yellow spots 1/8 to 1/4 inch across on the upper leaf surface in warm, moist weather. Management: cosmetic in most years, though susceptible cultivars can defoliate almost completely in late summer and fall, while 'Fantasy', 'Tonto', 'Tuscarora', 'Tuskegee', and 'Velma's Royal Delight' show field resistance.
Two threads. Symptoms: pale yellowish-green aphids with black spots, 1/16 to 1/8 inch long, on leaves and twigs. The eggs overwinter and hatch in spring, and maturity takes about 10 days, so several generations run each season. Management: ladybird beetles, green lacewings, hover fly maggots, and parasitic wasps work them over, and a wash of 4 ounces of dish soap per gallon of water, left three to four minutes and rinsed off hard, takes the film off the leaves.
Varieties by mature size
The cards run from ankle height to shade tree, in white, lavender, red, and every shade of pink, with the resistance rating each source gives.
Size classes and the room they need
Four classes cover everything on a nursery lot. Width decides the spacing, and it is the figure most tags leave off.
Hardiness zones, and how far north it grows
Crape myrtle is dependable through the middle South and the Mid-Atlantic, and the published range splits: zones 7a through 9a on one rating, 6a through 9b on another. That spread traces to a plant carrying two hardinesses in one body. Above-ground branches are considered winter hardy to zone 7, while the roots are usually, though not always, hardy to zone 5. Cold thresholds are reported two ways: top growth often dies to the ground below minus 5 degrees Fahrenheit, while root hardiness is put at minus 10. Temperature is only half of the story. Where a crape myrtle fails outright, the cause is usually a shortage of summer heat to drive vigorous growth and harden the wood.
Growing one in zone 6 works, with a change in expectations: with protection, top growth survives some winters in zones 5 and 6, though it may still take significant injury or die to the ground in a harsh one. Where the plant is only marginally hardy, the practical method is to plan for the dieback, cut the killed stems back hard in early spring every year, and let the roots rebuild the shrub over the summer. What that produces is a flowering shrub on an annual cycle, a fair trade for a gardener who wants the panicles and can do without the trunks and the bark.
Cultivar choice narrows the gamble. 'Natchez' is listed hardy in zones 6 to 9. 'Glendora White', an open plant of medium height with snowy white flowers, is rated hardy to zone 6, as is 'Velma's Royal Delight', a compact dwarf 4 feet tall and 3.75 feet wide with purple, mildew-resistant flowers, while 'Monow' is rated only to zone 7. Nursery marketing runs ahead of those ratings, and the difference is worth knowing before an order goes in. One series is advertised as reliably stem-hardy to zone 6 and root-hardy through bitter zone 5b winters, with container growing and a garage suggested for zone 4, on plants that mature at 24 to 30 inches in both height and spread.
The cold edge, zone by zone
At the cold edge the plant changes character, from tree to shrub to a woody perennial cut back every spring. The winter low decides which one you get.
Downsides, and where not to plant one
The trouble people have with a crape myrtle is nearly always a placement problem. Flowers can stain walkways and car paint, which is reason enough to keep the plant back from a front path or a driveway, and on some selections the falling petals mark paint while aphid honeydew leaves a sticky film on cars and patio furniture under the canopy. Roots come up constantly on homeowner boards, usually attached to a foundation or a sidewalk, and the landscape ratings for the species are mild on that point: roots are rated not a problem, and the fruit and leaves are rated not a litter problem. Size is where the complaints hold up. A tree-class cultivar set a few feet off a wall grows into the gutters and the window light, and at that stage the choice narrows to cutting it back every winter or taking it out.
Whether the plant belongs in a Southern yard at all is an open argument. It has naturalized in this country from Virginia to Arkansas south to Texas and Florida, and it appears on listings of species considered invasive in certain natural areas. The formal assessments split: Florida's assessment of non-native plants documents it as naturalized there and rates it not a problem species, while NC State's plant database tags the genus with a weedy descriptor. Where that question carries weight locally, or where a native planting is the goal, another summer-flowering shrub such as hibiscus is worth comparing before the hole is dug.
Planting
Plant a crape myrtle from late fall into early spring, and lean toward late fall, which gives the roots months to grow before the plant has to spend anything on leaves and flowers. Dig the hole at least two times wider than the root ball and set the plant no deeper than it grew in its container. Backfill with the same native soil that came out of the hole rather than a bag of amendment: research has shown organic matter is not necessary in an individual planting hole, and amendments inside it encourage roots to stay in the hole and skip the surrounding ground. Cover the hole with 3 to 5 inches of pine straw, pine bark, shredded hardwood mulch, or shredded leaves. Water thoroughly at planting, then once a week in the absence of rain for the first two months. Spacing follows the cultivar's mature width, which is what decides how close to a wall or a walk the plant can go.
Light
Crape myrtle does best in full sun, which is 6 or more hours of direct sunlight a day. Heavy shade costs twice over: growth and flowering drop, sooty mold builds on the foliage, and powdery mildew moves onto the flower buds and the young growth. A plant that flowered for a decade can stop without anything about the plant itself changing, because the shade around it grew in.
Water and soil
Average, medium-moisture, well-drained soil suits crape myrtle, and it takes loamy clay as long as the drainage is good. The pH range is wide, running from slightly alkaline down to acidic ground around 5.0 to 6.5, so most yards need nothing done to them. Once the plant is established it tolerates drought, which is why it holds up in parking strips and hot driveway edges where little else flowers in August. Water deeply and less often while it is young, let the surface dry between soakings, and watch the drainage more closely than the watering can.
Feeding
Feed a crape myrtle lightly or not at all, since over-fertilization brings excess growth and reduced flowering. Where a young plant does get fed, a complete general-purpose garden fertilizer such as 8-8-8, 10-10-10, 12-4-8, or 16-4-8 suits it, and a newly planted 1-gallon size takes 1 teaspoon monthly from March through August. The overdose that reaches most crape myrtles is never aimed at them: a lawn program run right to the trunk feeds the tree every time it feeds the grass, and the tree answers with leaves.
Height, spread, and growth rate
Species figures for crape myrtle are close to useless without a cultivar name attached. Published heights run 10 to 30 feet with widths of 15 to 25 feet, and mature specimens reach 40 feet. Growth rate is rated moderate, rapid, and moderate to fast, depending on the sheet. The height and width figures put a dwarf and a shade tree on the same line.
Bark and fall color
The bark is thin, smooth, and pale brown to gray, peeling and exfoliating in papery sheets as the plant matures, and on a multi-trunk plant the effect carries right through winter. It is the second reason to grow the tree and the first casualty of topping, since trunks need years of being left alone to thicken. Fall color comes in before the leaves drop, in yellow, orange, and red.
Propagation from cuttings
Crape myrtle roots easily from semi-hardwood cuttings taken during the growing season, and June, July, and August are the months for it: rooting hormone is generally unnecessary, and cuttings root in three to four weeks. The legal side matters more here than with most garden plants, because so many crape myrtles are patented. Propagating a patented variety is not lawful, and a patent expires 20 years after the original filing, so cultivars that reached the market in the early 1990s can now be propagated freely.
Toxicity, deer, and pollinators
Crape myrtle is listed as non-toxic to dogs, cats, and horses, so a tree over a dog run or a paddock fence raises no plant-safety question. Deer leave it alone as well, since the plant resists deer damage. The flowers do work for insects, serving as both nectar and pollen sources for pollinators. Researchers at the University of Georgia counted bee visits across 40 crape myrtle cultivars through July and August of two summers, and the visits landed unevenly: bees went most often to dark pink, dark purple, and white flowers, with honey bees favoring pink cultivars and bumble bees favoring lavender and dark purple ones.
Meaning and Southern history
Crape myrtle has come to stand for the American South alongside the southern magnolia, on the strength of how widely it is planted and how well it takes hot, humid summers with regular rain. Texas counts it among the state's symbols. The association is a matter of sheer quantity: street strips, parking lots, courthouse squares, and driveway pairs across the Sun Belt, all of them flowering through the weeks when the rest of the yard has given up.
Myths worth dropping
Four beliefs about crape myrtle survive every summer, and each one costs somebody a tree or a season of flowers.
The myth: You have to cut it back hard every winter or it will not bloom.
The reality: The idea that crape myrtles require pruning in order to flower is a misconception, and it is the reason millions of plants have been pruned very aggressively.
The myth: Crape myrtle is a Southern native.
The reality: The species is native to the Philippines, Japan, and the central Himalayas through southern China and Indochina. It came here as a garden plant and stayed.
The myth: It cannot survive a northern winter.
The reality: Winter injury in zones 5 and 6 lands on the top growth first, which is why gardeners there grow it as a shrub that rebuilds itself each season.
The myth: The mildew-resistant hybrids are just better selections of the same old plant.
The reality: 'Natchez' is a cross between Lagerstroemia indica 'Pink Lace' and Lagerstroemia subcostata var. fauriei, so a whole second species stands behind the resistance.
What to expect, year by year
A crape myrtle asks for the most attention in its first two summers and almost none after that.
Years one and two go into roots, and the plant is not established until roughly the end of the second year. Water it through every dry spell, keep the mulch topped up, and cut nothing off but dead wood.
The multi-trunk shape gets chosen next, the lower branches come off, and the bark starts to earn its keep: on 'Natchez' it mottles to dark cinnamon brown and exfoliates as the tree ages. Height comes fast in warm summers, and the trunks thicken enough to hold a full flower load without bending.
A mature plant runs on one dormant pass for dead and crossing wood, a spring look along the twigs for white felt, and water in a long drought.
Flower photos
FAQ
What month should I cut back a crape myrtle?
Late February into early March across most of the range, and the deadline is firm: the cuts go on before new growth begins in spring.
Is it too late to prune once the leaves are out?
For anything structural, yes. The buds for that summer are already forming on those new shoots, so cuts made now take the flowers with them.
Can a crape myrtle recover from crape murder?
It can, because hard pruning makes it sprout from the roots, the upper stems, and the base of the main stems. Keep three to five of the strongest outward-leaning shoots as the new trunks and clear everything else.
Do I have to prune it every year?
No. Given full sun, room to grow, and some distance from walkways and roads, it may need little or no pruning at all.
How do I get rid of the black on the trunk?
Scrub it off the trunk and lower limbs with a soft-bristle brush, water, and a bit of dish washing liquid. That is cosmetic, so the insect feeding underneath still has to be treated.
Will bark scale kill my crape myrtle?
The reported damage stops short of death: a heavily infested tree turns black and produces fewer and smaller blooms. Treatment goes on early in the growing season, late March through May, while the first generation of nymphs is out.
What is the most cold-hardy crape myrtle?
'Natchez' is rated for zones 6 to 9, and 'Glendora White' and the compact 'Velma's Royal Delight' are rated to zone 6 as well.
How big does a dwarf crape myrtle get?
The dwarf class runs 3 to 5 feet, and 'Pocomoke' and 'Chicasaw' sit in it. Individual ratings vary more than the tags admit: 'Pocomoke' is listed as 2 to 5 feet tall and wide on one page and as a true miniature at 1.6 feet tall by 3 feet wide on another.
Where should I not plant a crape myrtle?
Back from walkways and driveways, since the flowers can stain paving and car paint, and clear of any wall, eave, or wire the cultivar will grow into.
Are crape myrtles poisonous to dogs?
No. Crape myrtle is listed as non-toxic to dogs, non-toxic to cats, and non-toxic to horses.
Is it crape myrtle or crepe myrtle?
Both spellings name the same plant, after petals that look like crepe paper and leaves and bark that resemble true myrtle, with no kinship behind the name.
Interesting tips
- If aphids come back every summer, the cultivar list matters: 'Muskogee', 'Natchez', 'Tuscarora', 'Acoma', 'Tuskegee', 'Hopi', 'Pecos', 'Zuni', 'Biloxi', and 'Miami' all carry moderate resistance to them.
- Japanese beetles on a crape myrtle are rarely a crape myrtle problem. The adults are about 1/2 inch long, coppery brown with metallic green heads, and they feed on nearly three hundred plant species, so the population arriving on the flowers was raised on everything else in the neighborhood.
- A trunk treatment put on at the start of the season does not carry to frost: acephate painted around the trunk as a paste is systemic, moves into the leaves and twigs, and lasts through July, so a second application is what takes the tree to the end of the growing season.
Related Guides & Flowers
Hydrangea
The other summer shrub Southern gardens lean on, with its own color and pruning rules.
Dogwood
A small flowering tree that covers the spring weeks before crape myrtle wakes up.
Redbud
Color on bare branches in early spring, at the other end of the year from crape myrtle.
Types of flowers
The full index of flowers on the site, sorted by type, season, and color.