PRUNING

Pruning is the removal of entire branches from previous years' growth, or even a large part of the trunk, for the purpose of creating or cleaning up the design of the tree. Because the structure can be seen and the tree will suffer less from using energy to deal with the wound, pruning is best done during the late winter when the tree is inactive and before buds sprout on the deciduous trees or in the summer when the tree is growing actively and producing energy.

In general, remove branches that grow straight up, straight down or parallel to nearby branches. Remove dead branches unless they are part of the design. It is best to remove branches at their base using a concave cutter that leaves a depression at the cut. Later, when the callous forms, the cut will be flat and less noticeable. For the best results, do not cut all the way into the trunk; leave the "callous collar," which is the slight bulge around the base of the branch. This will allow the cells in this area to wall off the wounded area without allowing the rot to extend too far above, below or inside the wound. In the past, many people recommended using a sealant on the cuts if they are larger than a pencil in diameter. Sealants such as "Cut-Paste" or "Bonsai Bond" or even Elmer's glue have been applied to the cut surface to keep the healing cambium cells moist and to supposedly prevent rotting and infection. Actually, horticultural studies have failed to show any benefit to the health of the tree from sealing wounds. Sealants may make the "wound wood" grow and appear to cover the wound faster, but they also may result in more rotting of the wounded area. If you make your pruning cuts properly and at the right time, the tree itself will compartmentalize the wound and blockade infection and rot.

If you can avoid it, do not prune heavily during the spring when the tree needs its stored energy to bud. Cuts will not heal as well, and nearby branches (or the whole tree) might suffer or die. Do not prune in the fall because the branches are providing nutrients which are being stored for the whole tree. This process thickens the trunk and nourishes the tree for spring. Prune in the late winter or after the new foliage is mature and actively growing.