Georgia Gardener Newsletter Design Tip

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.