Future damage to plant quality caused by girdling roots can be reduced at planting time by disrupting the root pattern. This will cut most of the roots and encourage outward root growth in the soil. The butterfly method, which may seem harsh at the time, involves making a vertical cut from the bottom to halfway up the soil ball. The cut is made completely through the root mass, which is then spread or flattened in the planting hole. This technique not only disrupts the root pattern, but allows for shallower planting.
Shallow planting can be an important element for success in heavy or slowly drained soils.
Take care not to cut too far up into the root system, which may damage the crown of the plant. I find the next barrier to optimum plant establishment is the lack of water during the first growing season. Granted, most gardeners will water newly set material the day it is planted, and maybe even for a few weeks afterwards. However, a quality root system will only grow into a uniformly moist soil and a soil that is moist all summer. If the soil surrounding the planting hole is drier than the backfill material around the root system, there will be a gradual movement of water away from the root system.