Nursery-bought crepe myrtles are a little different. They are not yet mature so their system is more delicate and requires a little extra TLC. October is the best time to transplant young plants.
Now, since timing isn't quite everything, there are a few things left that will determine the success or failure of your transplant. First, you need to select a location that will provide crepe myrtles with full sun. If there isn't an area in your garden that offers 8 hours of sun per day, crepe myrtles can survive on four to six. Be sure that it is not shaded in any way. Shade will result in dull foliage and flower colors. The soil must also be moist and have a decent drainage system. Water cannot pool around the base of the plant. When you are first planting crepe myrtles, the soil must be on the slightly acidic side. It is not necessary to maintain this acidity after the plant is established.
The hole should be wide enough to accommodate the root ball, which is normally around 3 feet, with additional room left on all sides. After planting, do not pack the dirt in around it, but rather fit it loosely with the soil you removed. Be careful while pulling your plant out of its nursery container. You mustn't damage the roots. This is more of a concern when you are digging it up from the ground. Once you have pulled the plant from either the pot or the ground, be sure that the hole is not too deep. Generally, it is better to have a shallow hole than too deep of one. This will prevent your tree from suffocating. It is important that you soak the plant after filling in the soil. Once the water seems to be pooling at the top, you can stop. You will need to water it frequently for the next six to eight weeks. After this point, your crepe myrtle should be adequately established and will need less attention. After establishment, you should only water every few days, or when the soil is slightly dry to the touch.
Although it may seem like quite a lot of work, it will be well worth the effort come spring time!