Post and Courier
July 14, 2014

Have mercy on crape myrtles

Posted: 02/22/2014 01:00 p.m.


By Amy Dabbs

It is hard to resist using phrases like "crape murder" to describe the ill-advised practice of chopping the tops off crape myrtle trees each year. I am not sure where this idea began, but like an Internet video gone viral, once it has started, it can't be stopped. Perhaps the saddest victims are the beautiful older trees that have matured into well-formed specimens, only to be topped indiscriminately.

Experts describe topping as "the drastic removal of large-diameter wood, often several years old, with the end result of shortening all stems and branches, also known as heading, stubbing, rounding, and dehorning."

The truth is that crape myrtles (Lagerstroemia species) became such popular Southern landscape trees because they are small, low-maintenance trees that don't need a lot of pruning to perform well.

Introduced to the southern U.S. in the mid-1700s, "the lilac of the South," originally from Asia, has become part of the fabric of our landscape. Summer blooms of white, pink, lavender and red appear in clusters called panicles at the tips of new growth. In fall, the flowers turn to grape-like clusters of seedpods.

Fall colors can be startlingly pretty in shades of neon orange and red. After dropping their leaves, they expose their architectural trunks and interesting exfoliating tan, cream and cinnamon brown bark. They have been described as "living sculptures" when bare and leafless.

Managing the size of crape myrtles in small spaces often leads to topping or hard pruning. With the largest varieties reaching more than 30 feet tall with 15-foot-wide canopies, it's easy to see how a small yard can be quickly overtaken. Fortunately, many beautiful crape myrtle varieties are available in sizes ranging from dwarf (3-10 feet), semi-dwarf (11-20 feet), small (21-25 feet), medium (26-30 feet) and large-size trees (more than 30 feet).

Some experts suggest removing oversized trees and replacing them with an appropriate size variety for the site. While this may seem extreme, think of the landscape value gained and the pruning headaches lost.

Many gardeners believe that since flowers occur on new growth and hard pruning stimulates new growth, more flowers will occur. Ultimately, hard pruning results in trees expending excess energy in an effort to survive. The result is expressed in excessive vegetative growth, basal or "water sprouts," and flowers that appear larger but are fewer in number.

Occasionally, professional arborists will employ a severe pruning practice known as "pollarding" to maintain a crape myrtle at a consistent height. This method, which requires the removal of older wood and subsequent annual pruning to maintain trees at the desired height, is a high maintenance practice, and can be difficult for home gardeners to achieve without damaging trees.

Even light pruning can stimulate new growth that may be killed by freezing temperatures if done too early. It is best to put off all pruning until well into the dormant period, typically mid- to late February in the Lowcountry.

Careful consideration and limiting cuts to minimize damage is referred to as selective pruning. Mature crape myrtles only need light pruning to clean up small suckers and branches that are crossed or rubbing against each other. Younger trees may need more shaping to create small vase-shaped trees; trimming the lower limbs is known as "limbing up."

Some gardeners prefer to snip off spent flowers during the summer to induce re-blooming. This practice, known as tipping or tip pruning, may be unnecessary due to the many varieties bred to bloom for an extended period, and is impractical when trees grow out of reach.

Always use clean, sharp tools to make precise pruning cuts, leaving no ragged or torn bark. To remove suckers, water sprouts or other small limbs, use hand pruners or long-handled lopping shears. A small handsaw or pole saw can be useful in removing larger dead, damaged or diseased branches.

Be sure that cuts are outside of the branch collar, or the raised ridge found where limb and trunk intersect. Cutting into the collar creates larger wounds in the trunk, which can lead to insect and disease damage.

For a complete resource of crape myrtle varieties, check out Clemson University's Landscape Horticulture's Crape Myrtle page http://bit.ly/1l1tRUO.

Gardening school

The fourth annual Carolina Yard Gardening School is now open for enrollment.

Join Clemson Extension and the Tri-County Master Gardeners for this one-day gardening event that includes hands-on gardening workshops and lectures.

This year we are joined by Amanda McNulty, host of SCETV's gardening show "Making It Grow," for a live show without the cameras but with all the fun.

The CYGS will be 8 a.m.-4:30 p.m. March 22 at the Charleston Exchange Park in Ladson. Registration is required and the cost is $75 per person.

To register, go to www.clemson.edu/extension/mg/counties/tri_county/ or email Amy Dabbs, Clemson Extension Horticulture Agent at adabbs@clemson.edu.

Plant sale

The Lowcountry Chapter of the Native Plant Society will hold its annual spring plant sale from 9 a.m. to noon March 15 at Charlestowne Landing. Go to scnps.org or email Colette DeGarady at cdegarady@tnc.org.

Amy L. Dabbs is a Clemson Extension Urban Horticulture Extension Agent. Send questions to gardening@postandcourier.com.