How to Prune a Osmanthus Bonsai? A Detailed Guide to the Key Pruning Techniques

  Pruning is extremely important for enhancing the ornamental value of potted osmanthus. Pruning, especially heavy pruning combined with comprehensive water and fertilizer management, has a very good regulating and promoting effect on improving the growth of aging potted osmanthus. It can reconcile the contradiction between the height of potted plants and the height of the greenhouse, and properly solve the problem of overwintering management of potted osmanthus in the north.

  Below is a pruning method for all osmanthus enthusiasts. In terms of shaping, both pruning and wiring are meant to change the bending form of branches and trunks and the space they occupy, thereby achieving the goal of tree shaping. In terms of maintenance and management, pruning is meant to maintain and preserve the landscape of an already shaped tree. According to the order of shaping, it can be divided into positioning pruning, reduction pruning, and thinning pruning.

  Pruning time:

   Grafted osmanthus should be pruned during the dormant season. During the plum rain season there is a lot of rain and high air humidity, and trees grow vigorously, so one should prune less or avoid heavy pruning; removing a large amount of branches and leaves will affect normal growth and in severe cases lead to death. In addition, heavy pruning should not be done near the end of autumn, because after severe pruning new buds will sprout one after another, and when a cold snap arrives the tender buds will freeze to death. The best time for heavy pruning and severe pruning is January to February, when the trees are in the dormant period.

  Generally speaking, trees with strong vigor and vigorous growth can be pruned more, while thin and weak ones should be pruned less. According to the shaping needs of the tree, one usually cuts off messy crossing branches, overlapping branches, parallel branches, whorled branches, opposite branches, thin and weak branches, diseased branches, and so on. The nutrients of the remaining branches are concentrated, so they can grow robustly.

  Pruning methods:

  The end face of the cut should avoid the large surface as much as possible and be cut at a 45-degree angle to the branch or trunk, with the leaf bud kept on the upper side of the slant. During the growing season, one can prune close to the leaf bud, which helps the wound heal. During the non-growing season, one can prune above the leaf bud.

  Positioning pruning: this refers to the first pruning for osmanthus shaping, determining which branches at different positions to keep and cutting off the excess branches. For tree stumps collected from the wild, after they survive cultivation they sprout many branches, and most of the branches must be cut off, keeping only the backbone branches needed for shaping; this is called positioning pruning.

  After positioning pruning, the number of branches, their positions, and the mutual distances between branches are determined, which directly affects the formal beauty of the osmanthus bonsai. Therefore, before pruning, one should carefully conceive the design and consider the form of the tree shaping; as the saying goes, “the idea comes before the brush,” and at the same time one should have “a fully formed plan in mind” before making the cut. This is because the choice of which branches to keep or discard depends on the establishment of the tree landscape form. The branches kept should grow robustly, with coordinated thickness from top to bottom, avoiding parallelism, symmetry, and overlap as much as possible, achieving an orderly arrangement of density and sparseness, spreading around the trunk from top to bottom and left to right, and possessing dynamic momentum.

  Reduction pruning: this is a pruning method that shortens branches, and it is also an important measure for tree shaping and maintaining the tree landscape. In terms of shaping, reduction pruning makes the tree dwarfed, the branches full, and the thickness from top to bottom moderate, with variations in bending, so three points should be noted in shaping:

  ① The thickness transition ratio between the pruned branch or trunk and the upper section branch or trunk is suitable;

  ② When reduction pruning, leave the direction and angle of the bud eye properly, so as to adjust the newly grown branches to reasonably occupy spatial positions;

  ③ Reduction-pruned branch sections should be short rather than long: the first section branch is longer than the second section, and the second section branch is longer than the third section branch. In terms of maintaining the tree landscape, for most shaped osmanthus bonsai, the vigorous water sprouts produced each growing season need reduction pruning to maintain a beautiful posture.

  Osmanthus bonsai mainly relies on bud pinching and tip pinching to control overly long branches and maintain the original appearance. Reduction pruning can be done during the dormant period, but is not suitable during the growing season. During the dormant period, severe pruning is carried out to remove various undesirable branches.

  Pruning of osmanthus bonsai depends on the tree; according to the tree posture, set the large framework well, remove other root suckers, overly dense branches, water sprouts, crossing branches, and diseased and weak branches, so as to allow ventilation and light penetration. For trees that are strong on top and weak below, the upper branches can be cut back by 1/3 to make the overall tree vigor robust, and at the same time apply a wound healing and antiseptic membrane to the pruning cut to protect the wound.