As you drive around the South, I challenge you to find a town without crepe myrtles. My town has planted white crepe myrtles along every main thoroughfare so that it looks like the trees are covered with snow as we swelter in the heat of July. Luckily, we have an excellent public works team that installed drip irrigation before they planted the trees, so they will survive for many years. Even a low-maintenance tree like a crepe myrtle needs water. Learn more about how much water newly established and mature crepe myrtles need to thrive.

Understanding Crepe Myrtle Water Needs

Once established, crepe myrtles are drought-resistant and withstand Southern climates if they are watered at least every other week. Newly planted trees, especially if you wait to plant a tree in bloom so you are certain about what color you’re getting, need much more water. We’ll cover watering specifics and how to avoid overwatering for your climate and type of soil.

Watering Guidelines for Newly Planted Crepe Myrtles

Before Planting

Just like a baby, a newly planted crepe myrtle needs plenty of care after it comes home from the nursery and during the first year. Get a good start by watering the tree while it’s in the plastic nursery pot so the roots are receptive to water once you get it planted. After digging the hole, fill it with water and let it percolate out into the surrounding soil before putting the plant in the hole. Once the tree is placed in the hole and covered with soil and mulch, water it thoroughly again with a garden hose.

After Planting

To get the tree off to a good start, water in the morning with a hose for 3-5 minutes daily for the first week, then 3-5 minutes every 3 days for the next 3 weeks. If the daytime temperature is above 85 degrees, continue this pattern for 4 more weeks.

Your new crepe myrtle needs at least 3-5 minutes of water weekly. Get yourself a rain gauge, and if the rainfall doesn’t measure up, you’ll need to supply the water with a garden hose or drip irrigation. Sprinklers are not a great watering system for the new tree because they may not apply enough water directly to the soil and leave wet foliage susceptible to diseases.

Overwatering and Underwatering New Plants

Overwatering and underwatering, indicated by brown or brittle leaves, can sound the death knell for a new crepe myrtle. Overwatering is most likely to occur if you have clay soils that don’t drain well. Crepe myrtles like moist roots but not drowned roots. If you have clay soil, consider tilling the area and adding lots of organic matter before planting, or plant it so that the soil line of the top of the root ball in the container is slightly above grade. 

Watering Established Crepe Myrtles

While mature crepe myrtles five years old and older are drought-resistant, if you want a tree full of flowers and lush foliage, the roots need water during dry periods. The most important period to monitor watering is before, during, and after the bloom period. As a rule, if rain is scarce, a crepe myrtle needs two to three gallons of water per inch of trunk diameter per week. Water only the root area slowly with a hose or drip irrigation so the water is absorbed into the soil—skip the sprinkler system! During the winter or periods of rain, a crepe myrtle does not require additional irrigation.

Special Considerations

• Rainfall totals: If your area is in a drought during periods of high temperatures, keep your crepe myrtle healthy by adding supplemental irrigation, especially if the tree is young.
• Soil type: Loose soil is best for crepe myrtles, but they can thrive in sandy and clay soils. If you have sandy soil, you may need to water more often because the water drains very quickly through sand. For clay soils, slightly reduce watering frequency because it takes so long for the water to be absorbed away from the roots.
• Mulching: If you don’t have a thick layer of organic mulch over the roots of your crepe myrtle, you’re wasting water by allowing it to evaporate too quickly. Mulch newly planted trees with at least a 2″ layer of your favorite organic mulch. Remember that mulch degrades over time and tree roots spread. Add fresh mulch at least once a year and keep moving out away from the trunk of the tree to maintain a nice, thick layer of mulch over the root zone.

Common Mistakes and How to Avoid Them

The most common watering mistakes for a crepe myrtle are overwatering and underwatering. If you begin to see signs of wilting, browning leaves, it may be that you’re overwatering and crowding out the oxygen in the soil that the tree needs to survive. If the soil stays soggy around the tree, consider moving it to another location with better drainage. Underwatering will reduce the number of blooms and can cause the tree, especially newly planted specimens, to die.

If possible, water in the morning to allow any overspray on the foliage to dry during the day. Always apply water directly to the roots.

Pay attention to rainfall amounts and soil moisture levels to help you determine if the crepe myrtle needs water. Typically, the soil should be moist about 12 inches deep after watering the tree. If you are experiencing a drought, continue deeply watering your tree until the leaves begin to fall in autumn.