Georgia Gardener Newsletter Design Tip: July 23, 2009

Crape Myrtles in the Garden

Crape Myrtle Culture

Crape myrtles are extremely popular plants in the southern parts of the U.S. and for good reason. They bloom during the hottest part of the summer when few other trees and shrubs have any flowers, tolerate a wide range of soil conditions, grow quickly, have a broad range of flower colors, a long bloom season (60-120 days) and are easy to grow. What's not to like. On the downside, they are used so much in landscapes that people get bored with them. As a designer, I was reluctant to use them only because everyone had them. However there are so many different sizes and colors, I think using crape myrtles in landscapes more often deserves some consideration.

The growing requirements for crape myrtles are really simple: full sun and well-drained soil. Crape myrtles will tolerate sandy soils, clay soils, rocky soils, etc. What they WON'T tolerate are soils that are poorly draining or stay damp/wet. Plant crape myrtles in full sun. By full sun, I mean 6-8 hours of continuous, direct, unbearable, miserably hot Georgia sun. If the location you've selected is so hot and sunny that you don't want to stand there in July and August, it's the right spot. Planting crape myrtles in less than 6 hours of sun will reduce the flowering and increase the problems with powdery mildew.

For purposes of this article, I've divided crape myrtles into somewhat arbitrary categories: Small (under 5 feet), Medium (6-12 feet) and Large (over 12 feet). Those that are under 5 feet tall are usually maintained in shrub form while those over 5 feet are usually maintained in tree-form, often with multiple trunks. See the section on pruning below for more details.

Small Crape Myrtles: To 5 Feet

While researching this topic, I was surprised to find such a large number of small crape myrtles. I think that nurseries should consider providing more crapes in this category because of the smaller size of many landscapes. Crape myrtles of this size can be massed together as a deciduous hedge or even grown as a groundcover or in containers.

Name Height Color Bloom Time Mildew Resistance
Rosy Carpet 1-2 Rosy Pink Late June-July Good
Sacramento 2-3 Red Mid/Late July Good
Pocomoke 2-3 Dark Pink Mid/Late July Very Good
Baton Rouge 2-3 Red/Pink July Fair
Delta Blush 2-3 Light Pink June-July Fair
New Orleans Myrtlette Weeping 2-3 Purple Mid/Late July Fair
Pink Blush 2-3 Light Pink Mid/Late July Fair
World's Fair Weeping 2-3 Red/Pink Mid/Late July Fair
Weeping Alamo Fire 2-3 Red July Fair
Chickasaw 2-4 Medium Pink Mid/Late July Very Good
Chica Pink 2-4 Pink Mid/Late July Fair
Chica Red 2-4 Red July Fair
Tightwad Red 2-4 Red July Very Good
Firecracker 3-5 Light Red Mid/Late July Very Good
Ozark Spring 3-5 Purple Early July Good
Velma's Royal Delight 3-5 Red/Pink Mid/Late July Good
Victor 3-5 Red June-July Very Good
Dwarf Low Flame 3-5 Red Late July Good
McFadden's Pinkie 3-5 Light Pink Late June-July Very Good

Medium Crape Myrtles: 6-12 Feet

These varieties are what I call the middle of the road. They are outstanding small trees that can be grown in smaller landscapes or even in large containers. They look nice massed together in groups or as stand-alone specimens.

Name Height Color Bloom Time Mildew Resistance
Okmulgee 6 Dark Red Mid/Late July Fair
Petite Embers 6 Dark Pink Mid/Late July Fair
Petite Orchid 6 Purple Mid/Late July Fair
Petite Pinkie 6 Pink Mid/Late July Fair
Petite Plum 6 Purple Mid/Late July Fair
Petite Red Imp 6 Red Early July Fair
Petite Snow 6 White Early/Mid July Fair
Dwarf Royalty 6-8 Purple Mid/Late July Good
Caddo 6-10 Pink Mid July Very Good
Hopi 6-10 Medium Pink Late June-July Very Good
Pecos 6-10 Medium Pink July Very Good
Prairie Lace 6-10 Red & White June Good
Tonto 6-10 Dark Pink July Very Good
Mandi 6-12 Dark Red Mid/Late July Fair
Acoma 8-10 White Mid June Very Good
Christiana 8-10 Dark Red Mid/Late july Fair
Coral Sport 8-10 Coral Early July Fair
Firebird 8-10 Watermelon Mid/Late July Fair
Zuni 8-12 Purple Late July Very Good
Centennial Spirit 8-12 Red July Very Good
Cheyenne 8-12 Red Mid/Late July Very Good
Pepperment Lace 8-12 Pink & White Early July Fair
Burgundy Cotton 10-12 White Late June-July Fair

Large Crape Myrtles: Over 12 feet

These are the true tree-form varieties of crape myrtle. Most of these are grown with multi-trunks and some have very interesting bark. Make sure to allow enough space for these plants to reach their mature size. The width of these plants varies, but you can usually count on it being 1/2 to 2/3 of the height. This should help you with proper spacing. This is the largest group of crape myrtles.

Name Height Color Bloom Time Mildew Resistance
Yvonne 12-15 Medium Pink Early July Good
New Snow 12-15 White Early July Good
Comanche 12-18 Medium Pink Mid July Good
Conestoga 12-18 Medium Pink Mid July Good
Byer's Regal Red 12-20 Red Mid July Good
Catawba 12-20 Purple Mid July Good
Lipan 12-20 Purple Mid July Very Good
Osage 12-20 pink Early July Very Good
Powhatan 12-20 Dark Purple Late July Good
Royal Velvet 12-20 Dark Pink Late June Good
Seminole 12-20 Bright Pink Mid June Good
Yuma 12-20 Light Purple Late July Very Good
Country Red 15-20 Red Mid July Very Good
Country Red 15-20 Red Mid July Very Good
Sioux 15-20 Pink Late July Very Good
William Toovey 15-20 Pink Mid July Good
Byer's White 15-20 White Late June Good
Sarah's Favorite 15-20 White Mid June Very Good
Townhouse 15-20 White Early July Very Good
Near East 15-20 Light Pink Late June Fair
Raspberry Sundae 15-20 Red/Pink Mid July Good
Twilight 15-20 Purple Early/Mid July Fair
Apalachee 18-22 Light Purple Mid July Very Good
Byer's Hardy Lavender 20-25 Purple Mid July Very Good
Dallas Red 20-25 Red Early July Good
Dynamite 20-25 Bright Red Early July Very Good
Potomac 20-25 Pink Late June Very Good
Red Rocket 20-25 Red Mid July Good
Tuscarora 20-25 Dark Pink Early July Very Good
Tuskegee 20-25 Dark Pink Late June Very Good
Arapaho 20-25 Red June-July Very Good
Carolina Beauty 20-25 Dark Red Early July Good
Glendora White 20-25 White Early July Fair
Special Red 20-25 Coral-Red Early July Fair
Watermelon Red 20-25 Red Early July Fair
Choctaw 25-30 Pink Mid July Very Good
Miami 25-30 Coral/Pink Early July Very Good
Muskogee 25-30 Light Purple Mid June Very Good
Wichita 25-30 Light Purple Early July Very Good
Biloxi 25-30 Pink Mid July Very Good
Natchez 25-30 White Mid June Very Good
Kiowa 30-35 White Late June Very Good
Basham's Party Pink 30-35 Purple Late June Good
Fantasy 30-35 White Late June Very Good

Proper Pruning

Two years ago, I attended a conference of Certified Arborists in which one of the lectures was about a lengthy research project that had been conducted on the pruning of crape myrtles. Several pruning techniques were applied to groups of crapes to determine if there were differences observed in bloom time, flower size and total flower mass. The results were interesting. Pencil pruning, the labor-intensive technique of removing smaller branches and cutting back longer branches to pencil diameter, seemed to produce the best overall results in terms of flower number and mass without affecting bloom time. Topping (aka crape murder) produced more new growth with good but delayed flowering and other side effects. No pruning at all seemed to have little effect on flower size and number. Which type of pruning technique you choose depends upon how much time you have and what you want the plant to look like in the winter and summer.

Most professionals are opposed to topping for several reasons. Repeated hard pruning is stressful on a plant. On crape myrtles, you often see hard-pruned plants develop knobs at the pruning site. New growth tends to be weak and may actually weep over when full of flowers. I have observed that murdered crape myrtles tend to be more susceptible to powdery mildew and tend to put out more suckers at the base. In my opinion, the best pruning technique is pencil pruning followed closely by no pruning at all.

Pruning crape myrtles is done in the winter from January through early March.

Crape Murder A Properly Pruned Crape Myrtle

Pests and Diseases

Although pretty tough landscape plants, crape myrtles do have issues with a few pests of which most are not serious. The most serious pest of crape myrtles is the Asian Ambrosia Beetle. This insect bores into the trunk and larger limbs of crape myrtles in order to lay its eggs. After laying her eggs, the female introduces a fungus to the egg chamber in order to feed her developing young. Unfortunately, the fungus grows and clogs the plant's vascular system. Even with light infestations, everything above the lowest egg chamber can die. The most common sign is the appearance of toothpick-like projections from the trunk. Fortunately it is possible to cut the crape myrtle back to the ground and start over. Other plants affected by AAB aren't so lucky. Once infected, there is no cure. Preventative sprays of what I call the "thrin" pesticides to keep the beetles off the tree can be somewhat successful in February or March. These products include cypermethrin, permethrin, deltamethrin and bifenthrin (which must be applied by a licensed professional).

Aphids are extremely common on crape myrtles and are the pest usually responsible for the black film that coats the leaves, limbs, trunks, ground and plants nearby. As aphids consume the plant tissue, they excrete honeydew which is high in sugar. Sooty mold grows in the honeydew excretion giving the plant the black look. Once coated, it's nearly impossible to wash off. Although unsightly, it usually not harmful in the long term and usually disappears over the fall and winter. Preventing the sooty mold involves controling the aphids either with yearly applications of systemic insecticides (such as Imidacloprid*) in early spring, seasonal sprayings with products labeled for aphids or by using a strong blast from the hose to wash the aphids off.

Japanese beetles are a seasonal pest of crape myrtles. They usually appear in early June in large numbers and tend to congregate on crape myrtles in what can only be described as a feeding-sex orgy. Usually they are gone in several weeks and since crape myrtles have such a long bloom period, it rarely disrupts the flowering enough to be a huge problem. If you want to control Japanese beetles, there are several insecticides labeled for that including sevin, malathion, insecticidal soap, etc. Personally, there are so many of these bugs, I don't bother trying to control them. I simply wait for them to go away. Applications of the systemic Imidacloprid* do seem to show some control. This must be applied in the early spring.

One disease is found fairly commonly on crape myrtles and that is powdery mildew. This fungal disease usually appears in early to mid summer and looks as if the plants have been dusted with a silver-gray powder (see below). Usually by the time it appears, control is going to be difficult. Repeated severe infections of powdery mildew can weaken the plants but usually it's considered more unsightly than damaging. Control of powdery mildew involves the spraying of fungicides before the disease gets going. My suggestion to avoid having to use fungicides repeatedly for powdery mildew control is to select only those varieties of crape myrtles with very good or good resistance and to plant them in full sun. Hard pruning of crape myrtles also seems to be associated with higher infections of the disease. So, go easy with the pruners.

With so many choices in size and color, I recommend that if you have a sunny landscape and want to add some summer color, consider putting in some crape myrtles. They are widely available at almost every nursery. As for companion plants, try Knockout roses, daylilies, coneflowers, black-eyed Susans, summer annuals, etc.

Additional Information

For more information, go to this web site from Texas A&M University. It has pictures of many cultivars.

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