Homeowners frequently wonder why their crepe myrtle shrubs develop brown leaves. The fact is, one simple reason cannot be given to account for this browning. That is because the nature of the issue depends on the time of year when the problem occurs.
We also have to be careful to specify that we are talking here about the whole leaf turning brown (sometimes accompanied by curling), or about the foliage browning around the edges, as opposed to the emergence of brown spots in the middle of the leaf.
Such spots can indicate Cercospora leaf spot, which is caused by a type of fungus (Cercospora lythracearum) -- and an entirely different problem. Give your bushes plenty of space (to promote good air circulation) when you plant them, and prune off (and properly dispose of) affected branches (to prevent transmission of the fungus) to ward off Cercospora leaf spot. Better yet, select cultivars resistant to this disease, a number of which you can find on the Alabama Cooperative Extension website.
Brown Leaves on Crepe Myrtles: the Why Depends on the When
But let's assume that the browning that you are seeing occurs on the entire leaf or around its edges (rather than in the form of spots). Consider two different scenarios:
- You witness the problem in summer
- You witness the problem in spring
If you are seeing brown leaves (or even partially brown leaves) on crepe myrtle shrubs at the end of a dry summer, your crepe myrtle's browning foliage could be due to drought.
These bushes flourish in the southeastern United States, where they are very popular due to their ability to withstand the summer heat. Nonetheless, they do need water, and they may dry up during especially hot summers during which there is little rainfall. Northerners who grow the bush (it is not nearly as popular in the North) are far less likely to experience a problem with their crepe myrtles drying out.
This is more of an issue for Southern growers, who garden under more extreme conditions in summer.
The result is browning of the foliage. The solution (in terms of preventative measures that you can take) to the problem is to provide the plant with artificial irrigation in sufficient quantity (keep the soil evenly moist, but not wet).
If, by contrast, you are seeing brown leaves on the plant in spring, it could be due to your area having experienced a cold snap. Crepe myrtle is not as tolerant of cold weather as many bushes are. An untimely drop in temperature after the tender leaves have made their appearance can spell death for them. Short of growing your bush in a sheltered area (which requires foresight), there is not much that you can do to avoid the problem of browning in this case.
Will My Crepe Myrtle Die?
Here is the good news: neither case of brown leaves (that is, either in summer or in spring) need be fatal to your crepe myrtle. Browning due to a moderate cold snap ruins the appearance of the plant, but it probably will not kill your shrub. And while this bush is more likely to die from drought, it is usually easy enough to remedy the situation with artificial irrigation once you detect the first hint of browning.
Obviously, in the latter case, vigilance is of the utmost importance. Keep tabs on your plants. Inspect them on a daily basis. Stay ahead of the game. If your crepe myrtle shrubs do not seem to be performing as they usually do, start asking questions. Many plant problems can be solved fairly easily if you learn about them soon enough and take appropriate action in a timely fashion. Do you tend to have trouble keeping up with your landscaping chores? Read my landscape maintenance checklist to stay organized.