The balsam fir (Abies balsamea) is the original yuletide Tannenbaum, grown in the cool, moist forests of alpine Germany. Today it is grown in tree farms all over the world, including the northern tier of the United States and Canada. Training and pruning practice for the balsam varies with the purpose it will serve. Although its main use is as raw material for paper, it is still a favorite yuletide decoration, along with its southern cousin, the Fraser fir and assorted pines.
Begin "pinching" balsam tips at two to three years of age to encourage branching. Balsams have an "open habit" of growth, meaning that they'll grow tall and lean with branches widely spaced on the trunk or "leader." Identify the leader and pinch lateral branches as they set out growth buds in the spring to encourage branching and denser growth.
Remove branches that meet the leader in extreme "Y"-shaped joints during the tree's dormant season in late winter. These branches may compete with the leader or they may pose a weakness in the tree, making it vulnerable to wind or storm damage. Dead or broken branches should be removed whenever they appear. To remove branches, prune just outside the branch "collar," a thick fold of bark through the "crotch" around and under the joint.
Triple-cut conifer branches. Start sawing up from underneath the branch about six inches out from the collar, then cut down all the way through the branch about halfway between the upward cut and the joint. This will leave a "stub" which can be sawed off with a downward cut on the margin of the collar. Triple cuts draw sap away from the area where the final cut will occur, making a clean cut easier. Remove only Y-joint branches and branches that cross or rub against others. Balsams should need pruning only to tame their sprawling growth habits into ornamental tree shape.
Shear trees that are ornamental or are destined for use as a holiday tree. Begin when they are a few years old with a pair of pruning shears. Use a hedge trimmer when they get older. Cut growing tips of branches beginning in May or June to stop current growth. Shape into a conical pyramidal-shape. Shearing will also help "bush-up" branches. Be sure to shear evenly, taking 10 to 12 inches off terminal branch ends each season. The mature tree will be shorter but fuller than a natural-shaped tree.
Remove lower branches during the dormant season to raise the crown of trees grown for height. Maintain two-thirds of the tree's crown and remove only one level of branches at a time using a triple cut. This improves air circulation and encourages vertical growth.