Crepe myrtles are hot right now. In fact, no subject is of more interest to Southerners this summer, not even the stirring Presidential campaign of Ron Paul.
Thus, the ever-generous, all-caring Grump will answer 10 of the most common questions about crepe myrtles directed his way every week.
1. What does crepe myrtle need to grow well and bloom?
Answer -- Lots of sun, well-drained soil, and extended summer heat. After suffering for so many years from hearing about how great gardening is in England, I am gratified to know that crepe myrtle hates it there. The summers aren't sufficiently long and hot.
Winter cold is another consideration for you people up north. Although some selections, such as 'Acoma' (white), 'Centennial Spirit' (dark red), 'Comanche' (coral pink), 'Hopi' (medium pink), 'Yuma' (lavender), and 'Zuni' (lavender), are reputed to withstand temperatures below zero, if zero temps are common where you live, I wouldn't plant crepe myrtle. It does best in Zones 7, 8, and 9. Instead, plant 'Pink Diamond' or 'Tardiva' hydrangea. (Both are selections of summer-flowering Hydrangea paniculata.)
2. When is a good time to plant crepe myrtle?
Answer -- When the plant is dormant, either in fall, winter (where winters are mild), or early spring. Of course, you can plant a crepe myrtle grown in a container in summer too, as long as you water it frequently to keep it from wilting. Once it's established, it's quite drought-tolerant.
3. When should I prune crepe myrtle?
Answer -- Late winter is the best time for two reasons. One, the plant has no leaves, so you can easily see all the branches and which ones need removing. Two, crepe myrtle blooms on new growth. Pruning in winter won't reduce summer blooming.
Having said that, you can produce a second major flush of blooms on most crepe myrtles by pruning off the round, green seed pods that form just after the first flowers fade. The second flush won't be quite as showy, but you'll like it nonetheless.
4. What is "crepe murder?"
Answer -- Crepe murder is the odious practice of using saws and loppers to cut down a crepe myrtle into thick, ugly stubs, usually performed on an early spring weekend by bored husbands seeking to justify their existence to women. This ruins the natural form of the plant, produces weak spindly branches too weak to hold up the flowers, and prevents the formation of the beautiful, smooth, mottled bark that looks so pretty in winter.
5. What's that black stuff all over the leaves?
Answer -- Hershey's Dark Chocolate. Nah, just kidding. Actually, it's black mold growing on the sticky honeydew produced by sucking insects, usually aphids. Get rid of the aphids and you'll have no mold. Spray according to label directions with an environmentally friendly product, such as refined horticultural oil on insecticidal soap (make sure to wet the undersides of the leaves), or a systemic insecticide that's absorbed into the leaves, such as Ortho Max Tree & Shrub Insect Control.
6. White that's white stuff all over the leaves and flower buds?
Answer -- Powdery mildew, a fungus that likes warm, humid weather. Many older types of crepe myrtle are highly susceptible. The fungus distorts the foliage and often ruins the flower buds. While you can prevent powdery mildew by spraying according to label directions with a fungicide such as Daconil or Immunox or even with refined horticultural oil, you're better off buying a mildew-resistant selection, such as 'Natchez,' 'Miami,' 'Sioux,' 'Dynamite,' and 'Biloxi.' Look for this on the plant label.
7. Why doesn't my healthy crepe myrtle bloom?
Answer -- Could be lots of reasons. Maybe it doesn't get enough sun. Maybe powdery mildew ruined the blooms. Maybe Japanese beetles ate it. Maybe it just needs a few more years to grow. Maybe you're in a drought. A crepe myrtle will often go dormant during a very dry summer with flower buds ready to pop. They'll only pop when the plant gets some water, either from rain or from you.
8. What are some crepe myrtles that don't get so tall?
Answer -- One way to avoid crepe murder is to select varieties that don't need pruning. Small ones (5-10 feet) include 'Acoma,' (white), 'Hopi' (pink), 'Tonto' (red), and 'Zuni' (lavender). Dwarf types (3-5 feet) include 'Centennial' (purple), 'Petite' (various colors), 'Razzle Dazzle' (various colors), 'Pocomoke' (rose-pink), and 'Victor' (deep red).
9. What are the Grump's favorite crepe myrtles?
Answer -- 'Natchez,' (tall white), 'Miami' (tall pink, pictured above), 'Catawba' (medium purple), 'Dynamite' (medium red), 'Watermelon Red' (tall red), 'Petite Orchid' (dwarf purple).
10. Why do you spell crepe myrtle with an "e"?
Answer -- It never ceases to amaze me how many people think this spelling is the most significant issue facing the world today. I spell it with an "e" because the crinkled flowers remind me of crepe. If you want to spell it "crape," go ahead -- on your own blog.