June 30, 2017
From The NC State extension.
The advantage of using plants grown in containers is that 100% of the roots are in the container. Thus, the plant goes through limited transplant shock if given adequate follow-up care. Container-grown plants can be planted into the landscape year-round. Plants produced in containers, in a soilless medium (usually bark and sand), are much lighter than B&B material. This is very helpful to home gardeners who may not have large equipment to handle the heavy plants.
The main disadvantage of container-grown plants is the possibility of deformed roots. “Rootbound” plants have roots circling inside the container. The entangled roots are a physical barrier to future root growth and development. If this condition is not corrected at planting time, the plant may experience slow growth and establishment because of the girdled roots. Some form of root mass disturbance is recommended before planting.
A relatively new production system is the use of fabric containers or bags. Plants are grown in the bags, placed in the ground, with a soil backfill. The advantage to this production technique is purported to be a means of harvesting a greater number of roots while using field production practices. The fabric must be removed at transplanting time. This can be somewhat of a problem when the roots have become attached to the walls of the bag, or if roots have escaped through the fabric.
Smaller plants live better and establish faster than large plants and are more economical. Many consumers, on the other hand, want the “instant” landscape look. Demand for large, landscape-size trees has certainly increased over the last decade. With large mechanical digging equipment, 6- to 8-inch diameter trees can be moved. Large diameter trees are often transplanted for instantaneous effect, but post-transplant stress and costs increase with the size of the tree.