How Large Are the Roots on Crepe Myrtles?

Dwarf and Small Crape Myrtles

• These 3- to 10-foot varieties function well as yard shrubs. Most varieties are multi-stemmed Lagerstroemia indica. The full spectrum of crape myrtle colors -- pink, red, lavender, purple and white -- are available in small crape myrtles. Popular varieties are Aconia, Hopi, Tonto and Zuni. Branch spread is the determining factor in choosing a planting location. Since plants are essentially ball- or fountain-shaped, you should allow approximately 10 feet between house walls and the planting site. The branches may spread 5 to 8 feet in each direction, so 10 feet of clearance allows for root spread and the development of flowers, which bloom on new growth.

Medium-Sized Crape Myrtles

• Ranging from 10 to 20 feet in height, these Lagerstroemia often grow or can be pruned to a single tree-like trunk. Branch spread and root spread are closely linked, so much so that the area around the plant to be fertilized is determined by the branch spread. North Carolina University's Urban Integrated Pest Management Program notes that crape myrtles of this size and taller generally have shallow fibrous root systems and the growth pattern of these systems makes crape myrtles viable candidates for urban landscaping, where soil may be surrounded by paved areas. A full range of colors is available in these large shrubs/small trees. Among popular choices are Apalachee, Catawba, Conestoga, Osage and Royal Velvet.

Large Crape Myrtles

• Even the largest tree-shaped crape myrtles do not merit complaints about extensive or invasive root systems. Wichita, Natchez, Potomac, Standard Red and Miami are among large crape myrtle varieties, which can reach up to 30 feet in height. While some trees may have root systems extending up to three times the size of the crown, crape myrtles tend to have roots that extend to the drip line, that is, the edge of the canopy.

Planting Crape Myrtles

• A hole should be dug two to three times larger than the size of the root ball in circumference and slightly shallower than the height of the root ball. Roots need to be untangled by hand and spread out to fill the planting hole. The collar, or area where roots attach to the stem(s) or trunk, should ride very slightly, perhaps an inch, above the filled planting hole. Young trees may be mulched, but a cuff of bare earth 3 to 4 inches wide should surround the stem(s) or trunk. Situated thus, crape myrtles will develop the roots they need to support beautiful flowers.