Learning how to prune Japanese plum tree is an essential skill for any gardener wanting a healthy, productive tree. Pruning a Japanese plum tree focuses on creating an open structure that allows sunlight to reach the developing fruit. This guide will walk you through the entire process, from the tools you need to the specific cuts to make each season.
Proper pruning prevents disease, encourages strong growth, and maximizes your harvest. Without it, trees become dense, fruit quality suffers, and branches may break. We will cover the best times to prune, different training systems, and common mistakes to avoid.
How To Prune Japanese Plum Tree
This section provides the core principles and steps for pruning your tree. Japanese plums (Prunus salicina) are vigorous growers that produce fruit on both long-lived spurs and one-year-old shoots. Your goal is to manage this energy.
Essential Pruning Tools And Safety
Using the right tools makes the job easier and helps you make clean cuts that heal quickly. Dirty or dull tools can damage the tree and spread infection.
- Hand Pruners (Secateurs): Use for small branches up to 3/4 inch in diameter. Bypass pruners are preferred for a clean cut.
- Loppers: These provide leverage for branches up to 1.5 inches thick. Long handles help reach into the canopy.
- Pruning Saw: Necessary for removing larger limbs. A curved saw is often easier to use in tight spaces.
- Pole Pruner: For reaching high branches safely from the ground. Ensure the cutting head is sharp.
- Safety Gear: Always wear protective gloves and safety glasses. Sturdy boots and long sleeves are also recommended.
Before you start, disinfect your tools with a solution of isopropyl alcohol or a diluted bleach mix. This is crucial, especially when moving between trees, to prevent spreading diseases like bacterial canker.
The Best Time To Prune Japanese Plum Trees
Timing is critical for plum trees. Unlike some fruit trees, plums are best pruned at specific times to minimize disease risk and direct the tree’s energy.
Dormant Season Pruning (Winter)
The primary pruning window is late winter, just before bud swell in early spring. At this time, the tree’s structure is visible, and the risk of spreading silver leaf disease (a serious fungal infection) is lower because the spores are less active in cold weather. Avoid pruning in fall or early winter, as wounds will remain open and vulnerable for too long.
Summer Pruning
Light summer pruning is useful for managing growth. You can remove water sprouts (vigorous vertical shoots) and thin out overly dense areas in late spring or early summer. This directs energy to fruit development and improves air circulation. Never do heavy cutting in summer, as it can stress the tree.
Understanding Tree Structure And Growth Habits
Japanese plums fruit on a combination of spurs (short, stubby fruit-bearing branches) and last season’s new growth. They tend to grow many vertical, fast-growing shoots called water sprouts. Recognizing these parts is key to making smart cuts.
- Central Leader: The main, upright trunk. In an open-center system, this is eventually removed.
- Scaffold Branches: The main, permanent limbs that form the tree’s framework.
- Lateral Branches: Side shoots growing from scaffold branches. These will bear most of the fruit.
- Water Sprouts: Fast-growing, non-productive vertical shoots from branches or trunk. These should usually be removed.
- Suckers: Shoots growing from the rootstock or base of the trunk. Remove these completely.
Step-By-Step Pruning Guide For Young Trees (Training)
The first few years are about shaping the tree for its future. This is called training, and it sets the stage for all future pruning and harvests.
First Year (At Planting)
- If you have a whip (a single stem with no branches), cut it back to about 24-30 inches tall. This encourages low branching.
- For a feathered tree (one with side branches), select 3-4 strong, well-spaced lateral branches to become the main scaffolds. These should be at wide angles from the trunk and spaced evenly around it.
- Remove any other laterals and cut back the selected scaffolds by half to an outward-facing bud.
Second And Third Year (Dormant Season)
- Continue to select for 3-5 main scaffold branches. They should be about 6-10 inches apart vertically and point in different directions.
- Remove any branches competing with the central leader (if training to a central leader) or growing into the tree’s center.
- Shorten the main scaffolds by about one-third to an outward-facing bud or lateral branch to encourage further branching.
- Remove any weak, damaged, or crossing branches.
Step-By-Step Pruning Guide For Mature Trees (Maintenance)
Once the basic framework is established, pruning shifts to maintenance: keeping the tree productive, open, and at a manageable size.
- Remove the Three D’s: Start every pruning session by cutting out Dead, Diseased, and Damaged wood. Cut back to healthy tissue.
- Thin for Light and Air: Identify branches that are crossing, rubbing, or growing straight into the center of the canopy. Remove the weaker of any crossing pair and all inward-growing branches.
- Manage Height and Spread: Shorten overly long branches by cutting them back to a lateral branch that is growing in a desirable direction. This is called heading back.
- Remove Suckers and Water Sprouts: Completely remove all suckers from the base. Tear off water sprouts or cut them flush with the branch they’re growing from.
- Thin Out Fruit Wood: On older trees, thin out some of the older, less productive spurs to encourage new growth. Remove some of the previous year’s growth if it is too dense.
Common Pruning Cuts And Techniques
How you make the cut is as important as where you make it. Use these two primary techniques correctly.
Thinning Cut
This removes an entire branch back to its point of origin—either to the trunk or to a larger lateral branch. It opens up the canopy without stimulating excessive new growth around the cut. Use this for removing entire branches, such as scaffold limbs or large crossing branches.
Heading Cut
This shortens a branch by cutting it back to a bud or a smaller lateral branch. It encourages bushy growth just below the cut. Use this sparingly on mature trees, mainly to control length. Always cut to a bud or branch that is pointing in the direction you want new growth to go, typically outward.
Make all cuts just outside the branch collar (the slightly swollen area where the branch meets the trunk or parent limb). Do not leave stubs, as they won’t heal and invite decay. Also avoid cutting too flush, which removes the branch collar and damages the tree’s natural defense zone.
Training Systems For Japanese Plum Trees
You can train your plum tree into different shapes, depending on your space and preference. The two most common systems are open center and central leader.
Open Center Or Vase Shape
This is the most traditional and recommended method for Japanese plums. It creates a bowl-shaped tree with no central leader, allowing maximum light penetration and air flow.
- In the first years, you select 3-5 main scaffold branches growing from the trunk at wide angles.
- You then remove the central leader just above the top scaffold branch.
- Subsequent pruning keeps the center of the tree open by removing any upright growth pointing inward.
Central Leader
This method trains the tree to have a single, main trunk (the leader) with tiers of branches radiating from it. It’s more common for apples but can be used for plums in tighter spaces.
- The central trunk is maintained as the highest point.
- Scaffold branches are selected in whorls, with each tier spaced about 18-24 inches apart vertically.
- You must keep the upper branches shorter than the lower ones to prevent shading.
Seasonal Pruning Tasks And Calendar
Late Winter (Dormant Pruning)
This is your main work period. Complete all major structural pruning, thinning, and size control. The tree is dormant, so it will heal quickly when spring growth begins.
Late Spring / Early Summer
After the tree has leafed out, you can do light corrective pruning. Pinch off or cut back new water sprouts while they are still soft. Thin out any areas that are becoming too crowded that you may have missed in winter.
After Harvest
Some gardeners do very light pruning after picking the fruit. You can remove any broken branches or clear out obvious problem areas. However, keep this minimal, as major cuts now can stimulate new growth that won’t harden off before winter.
Advanced Pruning Considerations
Pruning Neglected Or Overgrown Trees
Reviving an old, unpruned plum tree requires patience. Do not try to correct years of growth in one season. Spread the work over 2-3 years.
- Year 1 (Dormant Season): Remove all dead, diseased, and damaged wood. Then, identify and remove the largest, most problematic branches that are crowding the center or crossing. Aim to remove no more than 25% of the live canopy.
- Year 2 (Dormant Season): Continue thinning out the canopy. Select a few more scaffold branches to remove to improve structure. Start lowering the tree’s height by cutting back tall branches to strong lateral limbs.
- Year 3 (Dormant Season): By now, the tree should be more manageable. Focus on fine-tuning the shape, further reducing height if needed, and encouraging new fruit wood.
Pruning For Fruit Size And Quality
While pruning itself improves fruit quality, you can combine it with fruit thinning for even better results. Japanese plums often set more fruit than the tree can support.
About 4-6 weeks after bloom, when the fruits are about the size of a marble, thin them by hand. Space fruits about 4-6 inches apart along a branch. This prevents branch breakage and allows the remaining fruit to grow larger and sweeter because the tree’s resources are less divided.
Common Pruning Mistakes To Avoid
- Pruning at the Wrong Time: Heavy pruning in fall or humid summer conditions increases disease risk.
- Topping the Tree: Lopping off the top of the tree to control height causes a flush of weak, poorly attached water sprouts.
- Leaving Stubs: Stubs do not heal and become entry points for insects and disease.
- Over-pruning: Removing more than 25-30% of the live wood in a single year can shock the tree, causing excessive suckering and reducing fruiting.
- Ignoring Tool Hygiene: Using dirty tools spreads infection from tree to tree.
- Forgetting to Balance Growth: Always consider the overall shape. Prune to maintain a balance between vegetative growth and fruit production.
Frequently Asked Questions
How Often Should You Prune A Japanese Plum Tree?
You should prune your Japanese plum tree every year during its dormant season. Annual pruning is much better for the tree’s health and easier on you than attempting a major correction every few years. Light summer pruning can also be done as needed.
Can You Prune A Plum Tree In The Fall?
It is not recommended to prune plum trees in the fall. Pruning wounds heal slowly at this time, leaving the tree vulnerable to fungal spores and winter injury throughout the colder months. The optimal time remains late winter.
What Is The Difference Between Pruning Japanese And European Plum Trees?
While the principles are similar, European plums (Prunus domestica) often have a more upright growth habit and bear fruit primarily on long-lived spurs. They require less aggressive thinning than the vigorous Japanese types. Japanese plums need more attention to managing their abundant, fast-growing vertical growth.
How Do You Prune A Plum Tree To Keep It Small?
To keep a plum tree small, use a combination of techniques. Employ summer pruning to check vigorous growth. When doing dormant pruning, use thinning cuts to remove entire branches rather than heading cuts, which stimulate growth. Consider training the tree as a fan or espalier against a wall if space is very limited.
Why Is My Plum Tree Not Producing Fruit After Pruning?
If you pruned too heavily, the tree may put all its energy into producing new wood instead of fruit buds. Excessive nitrogen fertilizer can have the same effect. Ensure you are pruning correctly and not removing all of the one-year-old wood where fruit buds form. Sometimes, a lack of pollinators or a late frost damaging blossoms is the true culprit, not the pruning itself.