Crepe myrtles are among the most ornamental trees available, emblematic of southern gardens. Their popularity stems from their generous crop of showy flowers. Although crepe myrtles are usually vigorous and hardy, it makes life easier if you have ready access to tips on caring for these gorgeous plants. We all have questions now and then, and Gardening Know How has answers. Here are the 10 questions readers ask most about crepe myrtle trees. 1) How and when do I prune a crepe myrtle? Sometimes you prune a tree to fortify or form it, sometimes you prune to please yourself. With crepe myrtles, the tree doesn't require pruning for health, vigor or branch structure. If you prune, it is to create a specific look, natural or formal. You can prune to open up the inside of the tree for a natural look. For natural pruning, clip out potential problems like broken or overlapping branches, then remove smaller inner shoots. Alternatively, prune formal-style, removing outer branches to shape the tree to particular height or width. In either event, prune in late winter or early spring. 2) Why is my crepe myrtle not blooming? Most gardeners plant crepe myrtle for the gorgeous flowers, so it's frustrating when your tree doesn't bloom. With attention, you can probably figure out the problem. If you pruned after the tree started bud production, you might have removed all the flower buds. But sometimes a tree can't bloom because tightly crowded branches prevent light and air from reaching the tree center. Too little sun can also result in a flowerless tree. If none of these describe your situation, check the soil. Too few nutrients or too much fertilizer can also explain why your crepe myrtle isn't full of flowers. 3) Are the roots of a crepe myrtle invasive? Crepe myrtle roots travel far and wide, spreading three times the width of the canopy. This might make you wonder whether they will dig into plumbing lines or sidewalks like some tree roots do. While it is never a good idea to plant trees close to walkways, septic systems or foundations, crepe myrtle roots shouldn't cause you worries. They are long, but shallow and weak. They won't strangle nearby plants or cause issues with pipes or driveways. On the other hand, don't plant flowers or grass under a crepe myrtle since the tree's roots can't compete well for nutrients. 4) What is blight on crepe myrtle? It's an awful moment when you look at your crepe myrtle leaves in early summer and notice that they are turning brown. If the spots are tiny black spore-bearing bodies, your tree may be suffering from tip blight. Blight can be caused by overly moist foliage, so immediately stop overhead watering and prune the plant to let the air pass through. You should apply a copper or lime sulfur fungicide as soon as you notice the browning leaves. Repeat the applications every 10 days throughout the wet season. It also helps to replace old mulch to prevent a new outbreak. 5) Why are there no leaves on my crepe myrtle? While crepe myrtle trees are known for frothy blossoms, the trees also need to have leaves for photosynthesis. If your crepe myrtle has few or no leaves, something isn't right. Check the tree for lines of ants. They suggest that your trees have a significant aphid problem. But your tree's problem could also be a late freeze that killed the young buds or stress from inadequate irrigation or pollution. If only a few branches aren't developing leaves, your crepe myrtle may have a disease called verticillium wilt. Prune the branches back to healthy wood, then dispose of the diseased portions. 6) Can I propagate a crepe myrtle with cuttings? Once you've experienced the joys of a crepe myrtle in your backyard, it's natural to want more. Propagating your own trees is inexpensive and fun. A popular method of propagating crepe myrtle is to sprout a cutting. Take tip cuttings in spring and plant them in sandy soil until they root. Covering them with a plastic bag helps keep them moist. Root cuttings also work to create new plants. Additionally, you can grow new crepe myrtles from the seeds of the plant. If you don't deadhead, spent blossoms produce berries that are followed by seed pods. Collect them for planting in spring. 7) Why is the bark is falling off my crepe myrtle? You may live with a healthy crepe myrtle in the garden for a few years, then wake up one day to find that the tree's bark is falling off. Don't panic. This is likely a perfectly normal phenomenon. One of the beautiful features of a mature crepe myrtle is peeling bark that reveals the coloration in the wood. But this peeling doesn't happen until the crepe myrtle is fully mature. So just sit back and enjoy the bark's display that adds winter interest to your tree. Of course, it's always a good thing. In some instance, insects may be to blame, so check for aphids or other pests. 8) What are these pests on my crepe myrtle? Crepe myrtle trees are not without their share of problems. If your crepe myrtle's leaf edges look tattered or you notice similar damage, your tree may have pests. One of the common pests that plague these large shrubs is spider mites. Look carefully at the crepe myrtle foliage for tannish spots on the leaves, pinpoints of red or white moving about the leaves and/or tell-tale cottony webs on the underside of leaves. Get them off your plant with strong jets of hose water or by bringing in hungry ladybugs. Crepe myrtles also attract eastern tent caterpillars, but these are more of an eyesore than a threat to your plants. 9) Why are there yellowing leaves on my crepe myrtle? Yellowing leaves indicate that all isn't well with your crepe myrtles. You can bet that the culprit is aphids if you see a sappy substance on the leaves or falling on the objects beneath the tree canopy. Aphids produce a sweet syrupy substance called honeydew when they infest a plant's foliage. Honeydew can attract other pests, like black sooty mold. Ants also love honeydew and often arrive in lines when the aphid population gets out of control. Aphids cause the leaves to become distorted and often yellowing occurs. Get rid of aphids naturally by bringing in insect predators like lacewings and ladybugs. Neem oil is also effective. 10) What are these shoots around the base of my crepe myrtle? If you see shoots growing around the base of your crepe myrtles, these are root suckers. The tree grows these suckers from its roots if it is stressed. Grafted trees and street trees always suffer from a little stress, so you are likely to spot root suckers regularly. Reduce the amount of root suckers by reducing the crepe myrtle's stress. Be sure it gets sufficient water and nutrients, limit pruning and check for pests. It's not hard to remove the suckers. Use pruning shears and clip them off as close to the tree as you can, leaving the collar intact. We all have questions now and then, whether long-time gardeners or those just starting out. So if you have a gardening question, get a gardening answer. We're always here to help.

Teo Spengler

Teo Spengler has been gardening for 30 years. She is a docent at the San Francisco Botanical Garden. Her passion is trees, 250 of which she has planted on her land in France.