In the Garden Articles

Crape Myrtles

by Joan S. Bolton

Let the spectacle begin.

The flowering of one of summer's showiest trees is about to get underway.

Most of the year, crape myrtles are quiet and unassuming, simply filling in as small, tidy trees. But give them heat, and their branch tips explode with eye-catching cones of flowers in vibrant shades of pink, purple, red and white.

The show lasts through September. Then you'll get another blast of color when the leaves turn yellow, orange or red in fall.

More often that not, crape myrtles are thought of as trees for hotter climates. They're prolific in hot spots like Fresno, Bakersfield, Riverside and San Bernardino.

But certain varieties will thrive on the Central Coast. You just have to be particular about what you buy.

They're certainly worth the hunt. Among their many attributes, crape myrtles are easy to grow. They fill in fast. They tolerate drought, heat, alkaline soil and frost. They won't lift pavement, so they're perfect for small spaces or next to driveways, patios and sidewalks. They're good under power poles because they're not likely to grow more than 20 to 25 feet tall.

Thanks to hybridization, crape myrtles are available as petite shrubs, massive shrubs, single-trunked trees and multi-trunked trees.

And they're zero emission where it counts. That's right. Just like a vehicle, they've been tested as to whether they produce hydrocarbons, which react with nitrogen oxides to form ozone, one of the main ingredients in smog. In the early 1990s, researchers at UC Riverside found that some popular landscape trees, including carrotwood and liquidambar, emit significant hydrocarbons. But crape myrtles emit none. Zero. So planting a crape myrtle is a positive step toward a cleaner environment.

By Way of Background

About 50 species of crape myrtle (Lagerstroemia) are native to eastern Asia and Australia. They were named after a Swedish merchant, Magnus von Lagerstrom of Goteborg.

Most of the crape myrtles in the United States are linked to two species -- one from China and another from Japan.

The Chinese crape myrtle, Lagerstroemia indica, was introduced in Europe in 1759, then came to North America a few decades later. It is the most widely planted crape myrtle today, thriving in the south, southeast and anywhere else with blazing summer heat. It's the state shrub of Texas.

The biggest down side of L. indica is that it's extremely susceptible to powdery mildew, especially in foggy, coastal areas. The fungal disease typically hits when the crape myrtles are blooming, and makes a mess of the leaves, buds and flowers.

The Japanese crape myrtle, Lagerstroemia fauriei, is not as showy. But it resists powdery mildew and bears beautiful, cinnamon-colored bark.

L. fauriei wasn't grown in the U.S. until the late 1950s, when Dr. John Cree, a director of the U.S. National Arboretum, collected specimens in the mountains of Yakushima Island in Japan. Arboretum botanists began breeding crape myrtles in 1959 and made what was then considered to be a revolutionary discovery: that crossing L. indica with L. fauriei resulted in mildew-resistant plants.

Breeding continued in earnest, and the arboretum has now introduced nearly 30 crape myrtle cultivars, most of which are complex crosses of the Chinese and Japanese species. All of the new plants bear native American names.

Natchez was the first Chinese-Japanese hybrid. It came out in 1978, bears white flowers from June to September, and grows 30 feet tall by about 35 feet wide.

Chickasaw, released in 1997, was the first true miniature cross, reaching only 20 inches tall and 26 inches wide after 7 years in a container, according to specs from the arboretum. Its pinkish lavender flowers bloom in mid to late summer.

So Many Choices

While crape myrtles are available as shrubs or trees, most of us are more likely to grow them as trees. After all, on the Central Coast, deciduous trees are deemed perfectly acceptable, while deciduous shrubs are often regarded as a lousy idea.

Regardless of the form, the best aspect of buying now is that you can select by color.

But before you fall in love with a particular hybrid, make sure there's Japanese heritage (Lagerstroemia fauriei) in the mix. Otherwise you could be setting yourself up for a lifelong battle with mildew.

Resistant candidates include Acoma, which blooms in white; Biloxi, pale pink; Chickasaw, light pinkish lavender; Comanche, coral pink; Hopi, medium pink; Lipan, medium lavender; Muskogee, light lavender; Natchez, white; Pecos, clear medium pink; Sioux, dark pink; Tonto, fuchsia; Tuscarora, dark coral pink; Tuskegee, dark pink to near red; Yuma, medium lavender; and Zuni, medium lavender.

If you live in a hotter inland area, such as the Santa Ynez Valley, also consider the Chinese (Lagerstroemia indica) hybrids. They include Catawba, which blooms in violet purple; Centennial, lavender; Centennial Spirit, dark-red; Chica Pink, bright pink; Chica Red; rosy red; Glendora White, white; Near East, pale pink; Peppermint Lace and Prairie Lace, both dark pink with a white edge; Red Rocket, bright red; Seminole, clear medium pink; and Watermelon Red, bright red.

In addition, there are several series of shrubby Chinese hybrids. Dixie blooms in red, lavender, purple and pink and has a weeping form. The Dwarf series bear pink, purple, red or white flowers and grow 3 to 6 feet tall and wide. The Petite serie grows 5 feet tall and 4 feet wide and bloom in red, lavender, pink, purple or white.

Care

Full sun and heat are key to prolific blooming. A shady spot with temperatures below 70 degrees F will not make for a happy tree.

Irrigation can be all or nothing. If you plant your crape myrtle in a lawn, you can expect more sucker growth to appear. Also be careful about mowing or trimming around the trunk, as the bark is fragile and easily damaged. Out in a dry, Mediterranean garden, crape myrtles are fine with no supplemental watering, once they've been in the ground for a year or two.

Go light on fertilizer, or avoid it altogether. Too much nitrogen can shift the plant's energy into producing more leaves, at the expense of producing flowers. If your crape myrtle is in a lawn, avoid applying nitrogen near the root zone. At most, apply a mild dose of a 5-10-5 fertilizer in spring.

If aphids descend on your new branch tips, spray them with a hose, release ladybugs or rinse the tips with diluted, mild dishwashing soap.

After blooming, the flowers will form seed capsules. You can trim them or let them hang all winter. Winter is also the time to admire the beautiful peeling bark in shades of tan, pink, gray, cinnamon and brown.

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Don't Commit Murder!

On the Central Coast, crape myrtles can be balky about leafing out in spring. But not to worry. While your young shrubs or trees are still bare, you can selectively prune to maintain their shape and enhance air circulation.

Don't commit "crape murder" by pollarding or cutting back major limbs. Besides weakening the overall health of the plant, severe pruning can produce stumpy flower clusters so heavy that they cause branches to sag or snap.

A light thinning is best. Be sure to prune before new growth starts, as flowering occurs on new wood.

Seeds of Wisdom

Remove spent flowers or seed pods on your crape myrtle after the first round of flowering to promote another cycle of bloom.