Cooperative Extension Service
The University of Georgia College of Agricultural and Environmental Sciences
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Crape Myrtle Culture
Gary L. Wade, Extension Horticulturist
Jean Williams-Woodward, Extension Plant Pathologist
Extension Horticulture, 224 Hoke
Smith Bldg., University of Georgia, Athens, GA 30602
Planting
Watering
Light Requirement
Pruning
Fertilizing
Propagating
Diseases
Crape myrtle (Lagerstroemia indica) is one of the most useful flowering
shrubs/trees grown in Georgia. It provides abundant summer color with a minimum
of maintenance. Because of these features, crape myrtle should be used more
often in the home landscape and as street trees in community developments. Crape
myrtle is ideally suited for community plantings since it is long-lived, withstands
droughts after becoming established, and is relatively free of disease and insect
difficulties. Colors range from red and pink to lavender and white. It is usually
best to use only one color in each cluster. Crape myrtle can be used effectively
with other summer flowering shrubs, such as althea, if you exercise care in
harmonizing colors.
During recent years considerable breeding work has resulted in a number of new crape myrtle cultivars (See Table 1).
Plant height ranges from less than 3
feet to more than 20 feet, making it one of the most versatile plants.
Some cultivars can be used as small foundation shrubs while others as
specimen trees.
Many of the newer cultivars also have improved flower color, better
fall leaf color, handsome bark and better cold and disease resistance
than the old
seedling types.
Crape myrtle will grow under adverse soil conditions. It grows and
flowers much better in well-prepared soil, however, so good soil
preparation is well
worth the effort involved. Preparation includes digging a large hole --
at least two times wider than the root ball. Set the plant in the hole
no deeper than it
originally grew in the container or field. Then backfill with the same
soil removed from the hole after breaking apart clods and removing
rocks or other
debris. Research has shown that organic matter amendments are not
necessary when planting in individual holes. Amendments in the hole
encourage roots
to stay within the hole and not grow outward into the surrounding
native soil. Amendments are most beneficial, therefore, when they are
incorporated
uniformly throughout the soil surrounding the planting hole.
After planting, water thoroughly to settle the soil around the
roots, and mulch to conserve moisture, reduce weeds and insulate the
roots against extreme
cold and heat. Three to five inches of pine straw, pine bark, shredded
hardwood mulch or shredded leaves placed over the planting hole is
ideal. Mulching
a larger area beyond the planting hole is even better.
Water crape myrtle plants thoroughly at planting time and once a
week, in the absence of rainfall, for the first two months after
planting.
Established crape myrtle plants will tolerate drought. Flowering is
enhanced, however, if plants are watered during dry periods that occur
during the
flowering season.
For strong growth and abundant flowering, plant crape myrtle in full
sun. Heavy shade will reduce growth and flowering and will increase
disease
problems such as sooty mold on the foliage and powdery mildew on the
flower buds and young growth. Large shade trees will also compete with
the crape
myrtle for moisture, causing poor growth and flowering. Lack of
sunlight and moisture are the common causes of poor growth and
flowering.
Crape myrtle flowers on new growth of the season, so you can prune plants any
time during the late winter or early spring before growth begins without loss
of flower buds. Avoid pruning in early fall before the first frost, because
pruning forces new growth and keeps the plant from going dormant. Severe freezes
can kill the plant if it is not fully dormant.
 |
| If you want a tree,
cut out all except one to five branches at ground level. Remove all side
branches up to the level where you want the limbs to start. |
Pruning results in an abundance of new shoots that form flowers. It also reduces
the amount of vegetative growth and funnels the energy of the plant into new
growth and flowers. Pruning, however, is not essential for flowering. Some of
the most spectacular floral displays can be seen on old, unpruned crape myrtles
along roadsides. Flower clusters are usually smaller on unpruned crape myrtles,
but the number of flower clusters is greater. Therefore, the overall floral
impact of the plant is not reduced.
On some cultivars, pruning to remove spent flower blossoms after
they fade will stimulate new growth and another blossom flush in late
summer. A
second bloom is sometimes difficult to force on cultivars that bloom
after mid-July.
The type and amount of pruning that should be done each year depends
entirely on desired shape and size. On large old crape myrtles, heavy
pruning may
not be advisable, since the tree form is the desirable feature. Crape
myrtles in tree form make wonderful accent plants or specimen trees.
Many cultivars
develop attractive trunks with exfoliating bark that add interest to
the winter garden (see Table 1).
To develop a tree shape, select three to five nicely spaced shoots growing
from ground level as the main trunks. Then remove side branches from these shoots
about halfway up their height. As the plant grows taller, more lower branches
can be removed each year so the canopy begins 3 to 4 feet above ground level.
You may also need to remove suckers (new young succulent spouts that grow from
the base) periodically in order to maintain the desired tree shape. Some landscapers
apply a synthetic plant growth regulator, called NAA (naphthalene acetic acid),
to suckers after pruning to prevent them from resprouting.
Some gardeners prefer growing crape myrtle as a compact shrub
instead of a tree. To get these results, prune the stems back to
approximately 6 inches
above ground level each year. Severe pruning will not kill or injure a
healthy plant. Prune before growth begins in the spring. The result
will be an
abundance of new flowering shoots.
If an intermediate size of shrub is desired, prune moderately by removing the
twiggy growth smaller
than pencil size. This annual pruning will stimulate more vigorous growth in
the spring.
 |
 |
| If you
want intermediate size shrubs, cut out only small branches less than pencil
size. |
Prune
back to within 6 inches of the ground each year if you want very low plants. |
When pruning, remember that new growth will emerge 3 to 4 inches
below where the limb is cut. Avoid cutting back large limbs and leaving
stubs,
because an abundance of new growth will emerge near the cut, looking
like pom-poms on stalks. Not only is this unnatural in appearance, but
this thick,
dense growth will be more susceptible to aphids. In the landscape
industry, this type of pruning is jokingly referred to as "crape
murder."
A complete general-purpose garden fertilizer -- such as 8-8-8,
10-10-10, 12-4-8 or 16-4-8 -- is ideal for crape myrtle. To newly
planted small plants (1-gallon size), apply 1 teaspoon of fertilizer
monthly from March to August along the perimeter of the planting hole.
Larger, established plants will benefit
from one broadcast application of fertilizer in spring. Apply 8-8-8 or
10-10-10 at a rate of 1 lb. per 100 sq. ft. or 12-4-8 or 16-4-8 at a
rate of ½ lb. per 100
sq. ft. Avoid over-fertilization because it causes excess growth and
reduced flowering. The best time to fertilize is just before a rain.
Otherwise, water in
the fertilizer after application with irrigation. It is not necessary
to remove mulch when fertilizing.
Crape myrtle is easily propagated from semi-hardwood cuttings taken
during the growing season. June, July and August are excellent times to
root cut-tings. Take cuttings from new growth of the season, leaving
three to four nodes per cutting and several leaves. Rooting hormone is
generally not
necessary, and cuttings should root in three to four weeks. Place
cuttings in a well-drained rooting medium in a shaded area and keep
them moist by
enclosing them in a clear plastic bag.
Cuttings also can be placed in prepared outdoor rooting beds.
Thoroughly cultivate the soil to a depth of 10 to 12 inches. Add 4 to 5
inches of organic
matter such as peat moss, leaf mold or pine bark to the surface and
thoroughly mix it into the soil.
Place the cuttings approximately 6 inches apart. Insert them
one-half their length into the soil. Mulch with 2 to 3 inches of pine
straw, leaf mold or pine
bark to conserve moisture. Keep them moist with regular misting.
The young rooted plants can be transplanted to their permanent location during the fall and winter.
Several diseases occur on crape myrtle including powdery mildew,
Cercospora leaf spot, root rot and sooty mold. Powdery mildew is the
most widespread
and serious disease in Georgia. Powdery mildew typically develops in
late spring and fall and is associated with warm day and cool night
temperatures and
high humidity. Leaves, young shoots and flowers are heavily coated with
a powdery, white mold that can distort new growth. Infected flower buds
may
not open, and severely infected leaves and buds often drop early.
The other most damaging disease is a leaf spot caused by the fungus Cercospora lythracearum.
Spots develop in mid-summer through fall during wet,
humid weather. Large, dark brown spots develop on lower leaves and
progress upward through the plant. Infected leaves turn yellow around
the spots and
drop prematurely. Sometimes even one spot will cause a leaf to drop on
susceptible cultivars and can cause significant defoliation prior to
frost.
Powdery mildew and Cercospora leaf spot can be controlled by
applying fungicides when the diseases are first noticed. Consult the Georgia Pest Control
Handbook
for current fungicide recommendations. The best approach to prevent
diseases is to plant disease resistant crape myrtle cultivars. A number
of
new crape myrtle cultivars from the U.S. National Arboretum and other
nurserymen are resistant to powdery mildew and Cercospora leaf spot.
(See Table
1) They are ideal for gardeners wanting low-maintenance landscapes.
Sooty mold is an unsightly superficial, dark brown or black coating on leaves
and stems that can be removed by rubbing. It is the result of a fungus growing
on honeydew excretions made by insects such as aphids, which are the most serious
insect pest on crape myrtle. Sooty mold usually causes little direct damage,
but it can cut vigor by reducing photosynthesis in the leaves. Using crape myrtle
aphid-resistant cultivars and insecticide sprays can reduce sooty mold.
Root rots can be prevented by growing plants in well-drained soil.
Table 1. Partial list
of popular crape myrtle cultivars by height
|
 |
Indicates
the cultivar is a release from the U.S. National Arboretum. |
 |
Indicates
the cultivar has shown resistance to Cercospora leaf spot in field trials. |
| - |
| Dwarf (3 to 5 ft.) |
|
Cultivar
Name |
Flower
Color |
Mildew
Resistance |
Exfoliating
Bark |
|
Baton
Rouge |
Deep Red |
|
|
|
Bayou
Rouge |
Deep Red |
|
|
|
Bourbon
Street |
Watermelon
Red |
|
|
|
Chica
Pink |
Bright
Pink |
|
|
|
Chica
Red |
Rose Red |
|
|
|
Chicasaw |
Pink Lavender |
|
|
|
Cordon
Bleu |
Lavender |
|
|
|
Delta
Blush |
Pink |
|
|
|
Lafayette |
Light
Lavender |
|
|
|
New Orleans |
Purple |
|
|
|
Petite
Embers |
Red Rose |
|
|
|
Petite
Orchid |
Dark Orchid
|
|
|
|
Petite
Pinkie |
Clear
Pink |
|
|
|
Petite
Plum |
Deep Plum
Purple |
|
|
|
Petite
Red |
Deep Crimson
Red |
|
|
|
Pink Ruffles |
Pink |
|
|
|
Petite
Snow |
White |
|
|
|
Pocomote |
Deep Rose
Pink |
|
|
|
Victor
Deep |
Red |
|
|
| 5 to 10 Feet |
|
Acoma |
White |
High |
Good |
|
Caddo |
Bright
Pink |
High |
Good |
|
Hopi |
Medium
Pink |
High |
Great |
|
Pecos |
Medium
Pink |
High |
Great |
|
Prairie
Lace |
Pink w/white |
Fair |
Average |
|
Tonto |
Red |
High |
Good |
|
Velma's
Royal Delight |
Magenta |
Good |
Average |
|
Zuni |
Medium
Lavender |
High |
Good |
| 10 to 20 Feet |
|
Apalachee |
Light
Lavender |
High |
Exceptional |
|
Catawba |
Violet
Purple |
Good |
Average |
|
Centennial
Spirit |
Dark Red |
Good |
Average |
|
Cherokee |
Soft Red |
Good |
Average |
|
Comanche |
Coral
Pink |
High |
Great |
|
Conestoga |
Pale Lavender |
Good |
Average |
|
Lipan |
Medium
Lavender |
High |
Exceptional |
|
Near East |
Light
Pink |
Moderate |
Average |
|
Osage |
Clear
Pink |
High |
Exceptional |
|
Powhatan |
Medium
Purple |
Good |
Average |
|
Raspberry
Sundae |
Pinkish
red w/white |
Fair |
Average |
|
Regal
Red |
Dark Red |
Good |
Average |
|
Royal
Velvet |
Bright
Pink |
Good |
Average |
|
Seminole |
Medium
Pink |
Good |
Average |
|
Sioux |
Vibrant
Pink |
High |
Great |
|
Wm Toovey |
Pink Red |
Good |
Average |
|
Yuma |
Medium
Lavender |
Good |
Good |
| 20 feet or more |
|
Basham's
Party Pink |
Light
Lavender |
Good |
Good |
|
Biloxi |
Pale Pink |
High |
Exceptional |
|
Byers
Standard Red |
Soft Red |
Good |
Average |
|
Byers
Wonderful White |
Clear
White |
Good |
Average |
|
Carolina
Beauty |
Dark Red |
Poor |
Average |
|
Choctaw |
Bright
Pink |
High |
Great |
|
Dynamite |
Cherry
Red |
Good |
Average |
|
Fantasy |
White |
High |
Exceptional |
|
Hardy
Lavender |
Medium
Lavender |
Good |
Average |
|
Kiowa |
White |
High |
Exceptional |
|
Miami |
Dark Pink |
High |
Great |
|
Muskogee |
Light
Lavender |
High |
Good |
|
Natchez |
White |
High |
Exceptional |
|
Potomac |
Clear
Pink |
High |
Average |
|
Red Rocket |
Bright
Red |
Good |
Average |
|
Townhouse |
White |
High |
Exceptional |
|
Tuskegee |
Dark Pink |
High |
Great |
|
Tuscarora |
Dark Pink
|
High |
Good |
|
Wichita |
Lavender |
High |
Great |
Leaflet 331/Reprinted April, 2001
The University of Georgia and Ft. Valley State University, the U.S.
Department of Agriculture and counties of the state cooperating. The
Cooperative
Extension Service, the University of Georgia College of Agricultural
and Environmental Sciences offers educational programs, assistance and
materials to
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Issued in furtherance of Cooperative Extension work, Acts of May 8
and June 30, 1914, The University of Georgia College of Agricultural
and
Environmental Sciences and the U.S. Department of Agriculture
cooperating.
Gale A. Buchanan, Dean and Director
