Regardless of plant species, growing conditions, soil type, etc., lateral roots of trees are 1.5 to 4 times the canopy width and are contained in the top 2 inches of soil. A tree's root system is not a mirror image of a tree's shoot system.
Planting holes should be two to three times wider and the same depth as the root ball of the tree to be placed in the planting hole. This procedure favors the lateral root growth. Excessive planting hole depth results in settling and sinking of the root ball.
Adding organic amendments to the backfill of a planting hole does not promote root growth. In most research conducted over the last 15 years, this practice actually inhibited top and root growth. Do not amend backfill soil.
Pruning shoot growth at planting reduces initiation of new roots. The first priority after planting is root growth. It has been erroneously thought for many years that pruning at planting reduces transplant stress and aids in establishment.
Pruning paints and wound dressings have no value. These materials allow moisture accumulation and are phytotoxic to beneficial fungi. The natural compartmentalization of decay in trees is inhibited by paints and wound dressings.
Never make flush cuts with the tree trunk. Prune outside the branch bark collar. It contains naturally occurring chemicals that protect the tree from disease and decay.