Pruning a Japanese ornamental cherry is a task that should be approached with a sense of respect for the tree’s natural form and a clear understanding of the goals to be achieved. Unlike many other landscape plants that require regular, hard cutting back, these trees generally look their best with minimal intervention. The primary purpose of pruning is not to force the tree into an artificial shape, but rather to maintain its health, enhance its elegant structure, and ensure its longevity. A few well-placed cuts made at the right time of year can make a significant difference, while improper or excessive pruning can cause irreparable damage and invite disease.
The golden rule for pruning ornamental cherries is to do so immediately after they have finished flowering in late spring or early summer. This timing is critical for two main reasons. First, it allows you to enjoy the full floral display without cutting off any of the flower buds. Second, and more importantly, it gives the tree the entire growing season to heal its wounds and to set new flower buds on its new growth for the following year. Pruning too late in the season can remove these newly formed buds, resulting in a sparse bloom the next spring.
It is strongly advised to avoid pruning these trees during the autumn and winter months. The cool, damp conditions of the dormant season are ideal for the proliferation of fungal and bacterial pathogens, such as those that cause silver leaf disease and bacterial canker. Pruning cuts made during this period heal very slowly, leaving the tree’s vascular system exposed and vulnerable to infection for an extended period. Pruning in the summer, when the tree is actively growing, allows it to seal off wounds much more quickly.
The overall philosophy should be one of subtlety and restraint. The goal is to work with the tree’s natural habit, whether it be weeping, spreading, or vase-shaped. The focus should be on the three D’s: removing any wood that is dead, damaged, or diseased. Beyond this, a light thinning to improve air circulation and remove any crossing or rubbing branches is all that is typically required. Heavy-handed shearing or topping of an ornamental cherry is a destructive practice that ruins its graceful structure.
Before making any cut, it is essential to use tools that are sharp and sterile. Sharp bypass pruners, loppers, or a pruning saw will make clean cuts that heal more readily than the crushed tissue left by dull blades. Sterilizing your tools with rubbing alcohol or a bleach solution between cuts, especially when removing diseased wood, helps to prevent the spread of pathogens from one part of the tree to another. This simple step is a crucial part of responsible pruning hygiene.
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The best time for pruning
The timing of your pruning cuts is arguably the most important factor in the health and flowering of your ornamental cherry. The period immediately following the end of the spring bloom is the ideal window. At this point, the tree has expended its energy on flowering and is shifting into a phase of active vegetative growth, producing new leaves and extending its branches. This active growth state means that the tree is able to respond quickly to pruning wounds, initiating the process of callusing and sealing off the cut tissue to prevent the entry of disease.
Pruning at this time also ensures that you will not sacrifice the following year’s flower show. Japanese ornamental cherries form their flower buds on wood that grew during the preceding summer. By pruning right after the current year’s flowers fade, you are removing wood before these new buds have had a chance to form. The new growth that is stimulated by the pruning will then have the rest of the summer to mature and develop its own set of flower buds for the next spring.
If you were to prune in the late summer or autumn, you would be cutting off the very branches that are laden with the invisible flower buds for the next season, leading to a significant reduction in blooms. Pruning in the winter is even more problematic. Not only does it remove the flower buds, but it also exposes the tree to a high risk of infection from devastating diseases like silver leaf and bacterial canker, which are most active in the cool, wet weather of the dormant season. The only exception to the “no winter pruning” rule is the immediate removal of branches that have been broken by snow or ice.
In summary, mark your calendar for the week after the last petals have fallen. This is your cue to get out the pruning tools. This disciplined timing allows you to achieve your pruning goals—whether for health, structure, or size management—while working in harmony with the tree’s natural life cycle. It is a simple rule that pays huge dividends in the form of a healthy tree and a consistently spectacular spring display.
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Pruning for health and sanitation
The first and most important priority of any pruning regimen is to maintain the health of the tree. This begins with the removal of what are often called the “three D’s”: dead, damaged, and diseased wood. This type of pruning can be done at any time of year, whenever you spot a problem. There is no need to wait until the post-flowering period to remove a broken or clearly diseased branch, as leaving it in place can pose a risk to the rest of the tree.
When removing dead or damaged wood, make your cut back to the nearest healthy, living tissue. You should cut into wood that is green and healthy, just beyond the point where the dead or damaged section begins. This ensures that all the compromised tissue is removed and leaves a clean wound on healthy wood that can heal properly. Look for a healthy, outward-facing bud and make your cut about a quarter-inch above it.
For diseased branches, it is critical to cut well below the visibly infected area to ensure you have removed all traces of the pathogen. For a disease like brown rot, which causes twig dieback, you should cut back at least six inches into healthy wood. After every cut into diseased material, you must sterilize your pruning tool in a solution of 10% bleach or 70% rubbing alcohol before making another cut. This prevents you from accidentally spreading the disease to healthy parts of the tree.
This type of sanitation pruning is a fundamental aspect of preventative healthcare for your tree. Dead branches can be a breeding ground for insects and fungi. Diseased wood is a source of inoculum that can spread infection. Broken branches create jagged wounds that heal poorly and are prime entry points for pathogens. By diligently removing this problematic wood, you are significantly improving the tree’s overall health and reducing the need for more drastic interventions later on.
Pruning for structure and form
Once the essential sanitation pruning is complete, you can turn your attention to improving the tree’s structure and aesthetic form. The goal here is not to force the tree into an unnatural shape, but to enhance its natural habit by creating a strong, open framework. One of the main objectives is to identify and remove any branches that are crossing or rubbing against each other. These rubbing branches create wounds in the bark that are highly susceptible to disease. When faced with two crossing branches, typically the weaker or less well-placed one is removed.
Another structural goal is to improve air circulation and light penetration into the center of the canopy. A dense, congested canopy can trap humidity and create an ideal environment for fungal diseases. By selectively thinning out some of the smaller, inward-growing branches, you can open up the structure, allowing air and sunlight to reach the inner leaves. This not only promotes better health but also showcases the elegant branching pattern of the tree.
It is also important to manage suckers and watersprouts. Suckers are vigorous, upright shoots that grow from the base of the tree or its roots, originating from the rootstock. These should be removed as soon as they appear, cutting them flush with the trunk or even digging down slightly to remove them from the root. Watersprouts are similar fast-growing, vertical shoots that arise from the main branches. These are often weak and disrupt the tree’s form, so they should also be pruned off flush with the branch they are growing from.
When making these structural cuts, always be mindful of the branch collar—the slightly swollen ring of tissue where a branch joins a larger limb or the trunk. Your final cut should be made just outside of this collar, without damaging it and without leaving a stub. The branch collar contains specialized cells that are responsible for closing over the wound. A proper cut angled away from the trunk allows the tree to compartmentalize and seal the wound efficiently.
Techniques for making proper cuts
The quality of your pruning cuts has a direct impact on how quickly and effectively the tree can heal. Always use sharp, clean tools appropriate for the size of the branch. For small twigs up to about half an inch in diameter, bypass pruners are the tool of choice. For branches up to an inch and a half, use long-handled bypass loppers. For anything larger, a sharp pruning saw is required. Anvil-style pruners should be avoided as they crush the plant tissue rather than making a clean slice.
When removing a small branch entirely, locate the branch collar and make your cut just outside of it. The angle of the cut should mimic the angle of the collar itself. This technique, known as a natural target cut, leaves the tree’s natural healing mechanism intact. Avoid making flush cuts that remove the collar, as this creates a larger wound that the tree cannot easily seal. Also, avoid leaving a long stub, which will simply die back and decay, potentially introducing rot into the main limb.
When shortening a branch rather than removing it completely, you should always cut back to a lateral (side) branch or a healthy, outward-facing bud. This is known as a reduction cut or a thinning cut. The lateral branch you cut back to should be at least one-third the diameter of the branch you are cutting. This ensures that the side branch is large enough to assume the role of the terminal leader and continue the growth, preventing the formation of a cluster of weak watersprouts at the cut site.
For large, heavy branches, a three-cut method is essential to prevent the weight of the branch from tearing the bark down the side of the trunk. The first cut is an undercut, made about a foot or two out from the trunk, cutting about one-third of the way up through the branch. The second cut is made from the top, an inch or two further out from the first cut, severing the limb. The weight of the limb will be safely removed. The final, third cut is the proper removal of the remaining stub just outside the branch collar.
Renovation pruning for neglected trees
Approaching a mature ornamental cherry that has been neglected for many years requires a patient and methodical approach. It is not advisable to try and correct years of overgrowth in a single season. An aggressive, hard pruning can remove too much of the tree’s leaf-producing canopy, severely stressing it and stimulating a panicked response of dense, unsightly watersprout growth. A gradual renovation over two to three years is a much safer and more effective strategy.
The first year of a renovation project should focus solely on the most critical issues. Start by removing all dead, damaged, and diseased wood. This sanitation pruning immediately improves the tree’s health and allows you to better assess its underlying structure. Next, identify and remove any major structural flaws, such as large, poorly attached limbs or branches that are severely crossing and rubbing against the main trunk or other primary limbs.
In the second year, you can begin the process of thinning the canopy. The goal is to gradually open up the structure to improve light penetration and air circulation. Selectively remove some of the smaller, weaker branches, focusing on those that are growing inwards towards the center of the tree or are clustered too closely together. Aim to remove no more than one-quarter to one-third of the living canopy in any single year.
By the third year, the tree should be in a much healthier and more open state. This final phase of the renovation can focus on the finer details, such as refining the tree’s shape and removing any remaining minor branches that are out of place. Once this multi-year process is complete, the tree can be maintained with light, annual pruning that focuses on preserving the improved structure and removing any new problems as they arise. This patient approach restores the health and beauty of the tree without compromising its long-term viability.
