The flowering cherry tree is a popular ornamental plant celebrated for its spectacular, though brief, seasonal display of blossoms. Proper pruning maintains the tree’s natural form, maximizes annual flowering, and contributes to its long-term health and structural integrity. Understanding the specific needs of this species ensures the tree remains vigorous and free from disease.
Determining the Right Time to Prune
The timing of pruning is important for the health and flowering of a cherry tree. Flowering cherry trees bloom on old wood, meaning flower buds for the following year are set during the previous summer. Pruning should be carried out immediately after the current season’s blossoms have faded, typically in late spring or early summer, around June or July.
Pruning at this time removes the least amount of next year’s potential blooms and allows wounds to heal quickly during the tree’s active growth period. Pruning in late fall or winter is discouraged because wounds are exposed when the tree is dormant and unable to form a protective callus. This extended exposure increases the tree’s susceptibility to fungal pathogens, particularly Chondrostereum purpureum, which causes silver leaf disease.
Essential Tools and Safety
Gathering the correct tools is necessary to protect the tree and the gardener. Bypass hand pruners provide a clean cut for small branches up to a half-inch in diameter, promoting rapid healing. Loppers are suitable for branches up to an inch and a half thick, while a sharp pruning saw is needed for larger limbs.
Clean and sterilize the cutting surfaces of all tools before use and between trees to prevent the spread of pathogens. Wiping the blades with a solution of 70% isopropyl alcohol or ethanol is effective and non-corrosive to the metal. This attention to tool hygiene is especially important for Prunus species due to their vulnerability to fungal and bacterial infections.
Core Pruning Techniques for Health and Structure
Pruning a flowering cherry tree involves a systematic approach, starting with cuts focused on the tree’s overall health. The first step is always to remove any dead, diseased, or damaged wood, known as the “3 D’s.” This can be done at any time of year if necessary to prevent the spread of infection. These branches should be cut back to healthy wood or to the branch collar.
Thinning and Structural Cuts
Thinning cuts manage the density of the canopy by removing branches back to their point of origin. This eliminates branches growing inward or crossing and rubbing against other limbs, which can create wounds and entry points for disease. Increasing light penetration and air circulation helps reduce the humid conditions favored by many fungi.
Structural cuts maintain the desired form of the tree, often a natural vase shape. This includes removing suckers, which emerge from the roots or base of the trunk, and water sprouts, which are vigorous, vertical shoots on the main branches. Both types of growth divert energy away from the main canopy and compromise the tree’s aesthetic shape.
Making the Proper Cut
When removing a branch, the cut must be made with precision just outside the branch collar. This collar is the slightly swollen area where the branch meets the trunk or a larger limb, and it contains specialized tissue that forms a callus to seal the wound. Making a cut too close to the trunk, known as a flush cut, removes this protective tissue and slows the healing process.
For branches over an inch in diameter, the three-cut method must be used to prevent the weight of the falling limb from tearing the bark down the trunk. This method involves an undercut, a top cut to remove the weight, and a final, clean cut just past the branch collar.
Common Pruning Errors to Avoid
One of the most damaging mistakes is the practice of “topping,” which involves indiscriminately cutting back the main leader or upper branches to an arbitrary height. Topping destroys the tree’s natural structure, creating numerous weak, upright shoots that are poorly attached and prone to breaking in storms. The resulting structural weakness and altered appearance are often permanent.
Another frequent error involves the improper execution of the cut itself, such as leaving a stub of wood or cutting too deeply into the branch collar. Stubs of wood will not seal over and become an invitation for pests and decay organisms to enter the tree. Conversely, damaging the branch collar by cutting too close to the trunk compromises the tree’s natural defense mechanism, known as compartmentalization.
Finally, removing too much of the canopy at once can severely stress the tree and trigger an undesirable growth response. A general guideline is to avoid removing more than 25% of the tree’s total leaf-bearing canopy in a single pruning session. Over-pruning can lead to excessive production of water sprouts, which requires more maintenance and ultimately weakens the tree.