For people who live below the Mason-Dixon Line, which by the way runs through Southeastern Pennsylvania, success with growing crape myrtles is simple. For those of us north of the line who long for that all summer color, it can be easy as well because several varieties are reliably cold hardy with proper planting and care.
A crape myrtle must be planted in full sun and well drained soil. Know the mature size of your crape myrtle so that you allow enough space in your garden. Some varieties grow to 15 or 20 feet high and 15 feet wide. Other dwarf varieties are appropriate for a shrub border growing to mature size of only 2 to 3 feet.
Dig an adequate size hole, about twice as wide as the root ball and amend your soil with rich organic matter. Miracle Gro Tree and Shrub soil is ideal.
Fertilizing is important for optimum health and maximum bloom. Plant-tone is excellent but if you have another all purpose food on hand, that will be fine.
We recommend mulching heavily to maintain moisture levels in the summer and to protect the roots in the winter.
Water deeply throughout the summer and into early fall 2 to 3 times a week when the hot dry weather is with us. Continue to water accordingly through the fall as needed.
Be prepared for leaves to emerge very late in the spring. Crape myrtles are the last plant to leaf out and can be as late as early to mid May. Do not panic. Trees and shrubs that bloom late leaf out late as well. Once the flowers appear in July, spectacular color remains through September.