Pruning Techniques

Twigs and Small Branches
When pruning twigs and small branches, always cut back to a vigorous bud or an intersecting branch. When cutting back to a bud, choose a bud that is pointing in the direction you wish the new growth to take. Be sure not to leave a stub over the bud or cut too close to the bud.

When cutting back to an intersecting (lateral) branch, choose a branch that forms an angle of no more than 45° with the branch to be removed. Also, the branch that you cut back to should have a diameter at least half that of the branch to be removed.

Make slanting cuts when removing limbs that grow upward; this prevents water from collecting in the cut and expedites healing.

Thick, Heavy Branches
Large branches should be removed flush with the collar at the base of the branch, not flush with the trunk. The collar is an area of tissue that contains a chemically protective zone. In the natural decay of a dead branch, when the decay advancing downward meets the internal protected zone, an area of very strong wood meets an area of very weak wood. The branch then falls away at this point, leaving a small zone of decayed wood within the collar. The decay is stopped in the collar. This is the natural shedding process when all goes according to nature’s plan. When the collar is removed, the protective zone is removed, causing a serious trunk wound. Wood-decay fungi can then easily infect the trunk. Even if the pruned branch is living, removal of the collar at the base still causes injury to the tree.

For over half a century, the recommendations for pruning have been to flush-cut and paint. These recommendations have no basis in scientific fact. The flush-cut increases the tree injury, which the paint hides. The paint is primarily cosmetic, a psychological treatment for the person doing the pruning, to show that he or she has done something to “help” the tree. In fact, paints or wound dressings may trap moisture and increase disease problems.

When cutting branches over 1 1/2 inches in diameter, use a 3-part cut. This is accomplished by first sawing the bottom of the branch, 6 to 12 inches out from the trunk and about 1/3 of the way through the branch. Next, make a second cut from the top, about 3 inches further out from the undercut, until the branch falls away. The resulting stub can then be cut back to the collar of the branch. If there is danger of the branch damaging other limbs below or objects on the ground, it must be properly roped and supported, then carefully lowered to the ground after the second cut.

Root Pruning
A tree growing in the woods or landscape for several years may develop long roots, running 15 to 25 feet or more away from the plant. These, along with many-branched side roots, physically support the tree. The area in a 3-foot radius of the trunk of the tree contains very few of the small feeding roots essential to gathering nourishment for the tree. These roots are usually located quite some distance from the trunk, branching off the long main roots. As a consequence, if the tree were to be dug and moved, a major part of the necessary feeding roots would be cut off in the balling operation; the tree might easily die when transplanted. This is the reason nurserymen root-prune nursery plants, to force them to grow a large number of small feeding roots near the base of the plant which are moved in the balling operation and ensure growth after transplanting.

To make it possible to safely dig small trees or shrubs in the woods, such trees should be root-pruned a year or so before they are moved. In the spring, sever half the roots by forcing a sharp spade into the soil around the plant alternately leaving a shovel width of untouched soil between cuts. The circle of cuts should be slightly smaller than the size of the ball that will eventually be dug. In the fall, sever the other half of the roots, thus cutting all the roots that are at a depth of a foot or less. The tree can then be moved the following spring.

Recent research indicates that most of the new roots grow from the cut end. Therefore, a root ball 4 to 6 inches larger than the root-pruned area must be dug to get the newly developed roots.

Root pruning is also used to force a vigorously growing fruit tree, wisteria vine, or dogwood into bloom. Using a spade to cut the roots early in the spring, as explained above, is all that is sometimes necessary to force a tree, shrub, or vine into bloom the following year.