The industry standard for large woody plants has always been balled and burlapped, or B&B. In this production style, liner trees are grown in the field until salable size. In order to ship them, they are dug with a mechanized spade. The root ball is wrapped with burlap, twine and/or a wire cage. Most often, digging is done in the spring or fall while the plants are dormant. There are several drawbacks to this style of growing: Most of the root system of the plant is left in the field, so transplanted trees must rapidly grow a new root system during the first year of planting to support the top growth. The root balls of field-dug plants can be extremely heavy, which can make planting difficult and expensive. Unless trees are root-pruned, it is not advisable to dig trees while in leaf; this limits custom orders to Spring and Fall. Some also believe that the difference between the native soil and the soil in the root ball can inhibit establishment.
A new system for growing larger nursery stock in bags has been gaining popularity. Liner trees are planted in a felt-like bag with a relatively light soil mix. These are then planted in the field, bag and all. As the root system of the small tree grows it fills the bag and some roots penetrate the bag into the surrounding soil. The bags encourage a well-branched, fibrous root system that is easily harvested with minimal root disturbance. The roots do not circle around the trunk, as roots often do in plastic containers.
Trees grown in these e bags establish extremely quickly, without the transplant shock that is associated with B&B material. This system also allows for a much smaller and lighter root system that is far easier to handle and plant, decreasing costs from harvesting to installation. Keep in mind, the bags MUST be removed just prior to planting. Having stocked trees grown this way, we advise a sturdy staking system at planting. Tree that we have brought in to the nursery grown this way have tendency to blow over in a much lighter wind than conventional B&B trees.
-Brad MacDonald