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How to Prune a Plum Tree

This blog post is all about how to prune a plum tree, but before we get into that, let’s talk about the benefits of pruning. Pruning not only helps maintain trees and keep them healthy, but it also allows more sunlight to reach leaves on the ground level and will make harvesting fruit easier!

So now you’re probably wondering what kinds of tools are required for this job. The best tool for removing branches from your plum tree is a lopper or hand saw; both work great so choose whichever one you want! Now that we’ve covered why and how to do this project let’s discuss when it should be done.

This article will explain how to prune a plum tree. Pruning is the process of cutting off branches, leaves or flowers to maintain the size and shape of a plant. In addition, it helps to prevent overgrowth that can cause disease and limit sunlight, air circulation and fruit production. The best time for this type of maintenance work is in late winter, before new growth begins in early spring when plants are still dormant.

Plum trees are the perfect first fruit tree for a home orchard. They are beautiful, fruitful, and easy to prune.  You’ve done the work of finding the right plum variety and putting it in the ground. Now, this article will equip you to prune a plum tree from year one to maturity. 

Why To Prune A Plum Tree

Fruits such as grapes, blueberries, or even peach trees will become unproductive without proper pruning. In contrast, plum trees can thrive even if you make a few mistakes when new to pruning. 

So, why is pruning plum trees worth the time? Basically, neglected trees will be smaller and bear less fruit than a pruned plum tree. There are four reasons to prune a plum tree. 

  • Prune a plum tree for a manageable shape that is open to sunlight penetration and air circulation. Nobody wants to fight their plum tree just to prune it.
  • Prune a plum tree to develop a strong framework of scaffold branches that won’t break under fruit load.  
  • Prune a plum tree to remove diseased branches or damaged wood. 
  • Prune a plum tree to encourage optimal fruit production of high-quality plums through stimulation of strong and healthy new growth. 

There’s no one system of correct pruning for plum trees. Feel free to experiment and find the type of pruning system that works best for you! As long as you don’t overprune, your tree should be just fine. 

Everything You Need to Prune a Plum Tree

Before you prune a plum tree, gather the equipment you need for the job. You can reuse all these products to prune other types of fruit trees, so invest in quality pruning tools that will last. 

Here’s the equipment you need to prune a plum tree: 

  • Pruning shears: hand shears for soft shoots, water sprouts, twigs, and foliage. 
  • Orchard loppers: loppers are heavy-duty shears for tougher branches. 
  • Pruning saw: a curved saw case you need to remove a diseased branch. 
  • Pole tree pruner: a long-handled pruner to reach that uppermost branch without climbing on a ladder. 
  • Garden gloves: gloves are indispensable to protect your hands from bushy growth. 
  • Pruning sealer: sealer is optional but can prevent infection of stumps or pruning wounds. Pruning sealer can also be used for grafting – it’s possible to add an apple branch to your plum tree! 

Plum Tree Growth Habits

When you prune a plum tree, keep in mind that its growth habits are different than those of apples or grapes. In addition, growth habits will depend on what type of plum tree you are growing. 

European Plum Tree Growth Habits

European plums fruit on spurs that are 2 years old up to decades. Therefore, European plum varieties such as the Cherry plum and yellow plums like the Mirabelle or Green Gage are very forgiving. Even if you cut back wood from the current season, they will still bloom and bear fruit. 

Japanese Plum Tree Growth Habits

Japanese plums fruit either on 1-year-old wood, much like peaches and on fruit spurs. Varieties such as the Satsuma plum and Elephant Heart are very fruitful, and up to half of the one-year-old shoots must be removed to prevent overproduction. Varieties like the Santa Rosa bear light crops, and only one fourth to one-third of new shoots should be pruned out. 

When to Prune a Plum Tree

From apple trees to peach trees to pears, most fruit trees are pruned during the dormant season. This is not true for plums. The best season to prune a plum tree is a mid-summer during full growth.

The exact time for pruning is variable, but a good rule of thumb is to prune a plum tree in June or July. It can seem wrong to prune off branches and shoots with fruit on them but resist the urge to leave the tree unpruned. There will be plenty of plums left! 

Times to Prune a Plum Tree in Dormant Season

Why don’t you generally prune a plum tree in the dormant season? The answer is that plum trees are prone to fungal infection, including the infamous Silver Leaf disease. Pruning in summer means there are fewer fungal spores in the air. Plus, the tree has more energy to resist fungal infections. However, there are a few times dormant pruning is the better choice.

Dormant pruning is acceptable in the case of limb breakage or at planting time. Broken branches should be removed as soon as possible, even in winter. It is better to make a clean cut and cover it with a wound paint than leave a jagged wound in the tree. 

If you live in a humid climate in summer, disregard advice about pruning in the summer. Late spring is likely the best time for you. Orchard growers in Minnesota, for example, find dormant pruning to work best since fungal spores abound during humid summers. Consider bee-safe fungicides to help keep the disease in check.

Newly planted trees should always be pruned for the purposes of tree training. You want to start growing the desired tree form right away. Pruning at planting is always necessary for pruning whips, but some suppliers will prune larger trees ahead of delivery. To minimise the risk of infection when you prune a plum tree at planting, keep these tips in mind: 

  • Do your initial pruning in late winter months or early spring before bud break. Choose on a dry day when there will be fewer fungal spores in the air.
  • Make clean, sloping cuts to keep water from pooling on pruning wounds. 
  • Watch carefully for silvering or frost damage as spring growth comes in. 

Fruit Thinning

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While fruit thinning is not specifically considered a pruning task, it may be necessary for quality fruit later on. Complete your annual pruning before you thin the plums, and don’t remove flowers from the bloom in spring. Summer pruning will remove fruit-bearing stems, which may be all that is needed. 

Why might fruit thinning be used for plum trees? A heavy crop of plums will weigh down even strong scaffold limbs. Furthermore, fruit quality is higher when fruit trees can concentrate sun energy collected by leaves into fewer maturing plums. 

Plum trees are known for their biennial bearing. They will produce a bumper crop of plums one year and then take a year off to store up energy and grow. Proper pruning and fruit thinning can help even out fruit production year to year. 

Here are the steps for proper fruit thinning: 

  • In May or June, if the tree is full of plums, remove some smaller fruit. 
  • Prune the plum tree. 
  • In early to mid-July, remove any damaged, bruised, or pest-ridden plums. 

How to Prune a Plum Tree

You’ll use a different pruning method for each main type of plum. Japanese plum trees and European plum trees are the most common varieties of plums. Because these trees grow differently, they do best with different shapes. 

Before you start pruning, keep two things in mind. First, always prune to a healthy bud in the direction you want new growth, which is usually upright and outward. Make clean pruning cuts for healthy stubs.

Second, carefully select scaffold limbs as the framework of your tree. Scaffold limbs should ideally be at  45 degrees to the tree. Branches with narrow crotch angles can split off the mature tree under a load of plums. 

How to Prune Plum Bushes and Pyramid Plums

If you’ve bought a dwarf plum, plum bush, or pyramid plum, pruning will look a little different. Fan training is a popular method to spread out the lateral branches of a short tree among horizontal wires. This makes the tree a pretty addition to the landscape and makes tree maintenance easy.

Here’s the process to prune a pyramid plum tree:

  • In the first year, cut a new tree to about 2 feet above soil level a, right above a bud. Make sure there are at least four buds below the cut.
  • In the second year, cut the main stem back about 12-20 inches. Lateral shoots will have grown from the buds you left the previous season. Prune all these lateral shoots to a bud, about 10 inches long.
  • If you’re using a fan training system, remove any branches to the front or back of your central leader and tie lateral branches to your horizontal wires.
  • Prune the mature pyramid plum by cutting back the central leader 12-20 inches to control height, and prune lateral branches back as necessary.
  • As always, remove dead, diseased, or crossing branches.

How to Prune a Japanese Plum Tree

Japanese plum trees should be pruned to a vase shape. This means you’ll have scaffold limbs pointing out from around a central trunk with an open centre. 

Here’s the step-by-step process to prune a plum tree of any Japanese variety: 

  • The first year, you’ll have a pruning whip or young tree that basically looks like a stick with buds. Prune the stem back to two or three feet above the ground. After the branches have grown a few inches, choose vigorous shoots as lateral branches of your scaffold whorl. Lateral branches should be evenly spaced around the tree. 
  • The first two or three years, cut back the scaffold whorl to 1 bud at the top and 2 buds at the bottom. 
  • Prune out diseased material or damaged wood and crossing branches. Make clean cuts. 
  • Starting at the lowest limb, cut off suckers, water sprouts, and any shoots or stems growing towards the tree’s centre or on the trunk below the scaffold limbs. Also, remove any secondary growth on the scaffold limbs within half a foot from the trunk. Leave upright shoots that are directed outward. 
  • Cut off one half to one-third of one-year-old shoots from the previous season to avoid overproduction of fruit. 
  • Head back scaffold limbs and upright limbs to a manageable height. Non-dwarf plum trees can grow twenty to thirty feet tall, so cut back tree height so you can pick plums. Plus, this activates phytohormones that will encourage fruit growth in the lower tree branches. 

How to  Prune a European Plum Tree

European plum trees should be pruned to a central leader shape. In a central leader pruning system, scaffold branches surround a single upright branch that is an extension of the trunk. In the summer, you’ll notice the tree canopy forms a pyramid shape. 

Here’s the step-by-step process to prune a plum tree of any European variety: 

  • The first year, cut back a pruning whip to 28-36 inches above the ground. Choose an upright branch as the central leader and a few evenly spaced branches to form the scaffold whorl. 
  • In the second and third years, choose strong and evenly spaced lateral shoots to become more scaffold branches. Keep these lateral branches cut back to about 10 inches or 2 buds. This concentrates growth into the central leader. 
  • In the first two or three years, cut the scaffold whorl branches at the top of the tree to one bud and the bottom branches to two buds. 
  • After three or four years, the tree will likely be growing tall. Prune back the trunk 12 – 20 inches at a bud each year, so fruit and vegetative buds concentrate in the bottom tree branches. 
  • Every year, cut out dead, diseased, or damaged branches. Also, remove unproductive shoots and any crossing branches. 
  • Cut off suckers and watersprouts at their source. 
  • If the tree is still too tall or bushy, cut out old-growth and secondary branches that grow inwards. Upright branches can be trimmed in length. 

How To Prune A One-Year-Old Plum Tree

First-year pruning is very easy, simply prune back the stem to about 1m / 3ft high in early to late March (see below for why at this time of year). If you are intending to grow your plum tree as a half-standard bush, then prune to 1.2m / 4ft or 1.6m / 5ft for a full standard.

You want at least two branches to form from the main stem, and these will come from buds clearly visible. So in year one, you may want to prune the main stem slightly higher so that a good bud or two, in the correct position, is left on the main stem.

It is important to prune a one year plum tree as soon as possible to help it establish a good structure. At the same time, pruning in winter exposes the tree to fungal infections. With these two conflicting factors in mind, we recommend pruning a one-year-old tree in mid-March.

The supplier of your plum tree will have told you the age of your plum tree when you bought it. If you don’t know the age of your tree using the diagram above and below to decide if your new tree is one or two years old.

Prune on a dry day and use a sharp pair of secateurs. Make the cut a sloping one to avoid water settling on the cut surface. Current advice is not to use a pruning sealant on the cut.

So we can get the timings correct for year two and three pruning, let’s assume you plant your new, one-year-old tree in January 2017 and pruned it for the first time in March 2017. The dates below will be based on this date.

How To Prune A Two-Year-Old Plum Tree

This section on pruning a two-year-old plum tree applies to the following two situations:

You bought a one year tree in January 2017 and pruned it shortly afterwards in March 2017 (see first year pruning above). This second-year pruning should occur in mid-June 2018.

You bought and planted a two-year-old tree in winter  and wish to prune it for the first time in mid-June 2018.

Prune back the main branches to a length of about 30cm / 12in. Prune back any side shoots to a length of 15cm / 6in. Prune weak shoots away completely and trim back any stems which are crossing. Prune on a dry day and use a sharp pair of secateurs. Make the cut a sloping one to avoid water settling on the cut surface.

During the pruning, cut the shoots and branches to an outward-facing bud to try and achieve the goblet shape with a clutter-free central part. If the position of an outward-facing bud only occurs further down the stem to be pruned, prune to that point.

How To Prune A Three-Year-Old Plum Tree

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Third-year pruning is the same as second-year pruning. Prune back the branches to a length of about 35cm / 14in. Prune back any side shoots to a length of 15cm / 6in. Prune weak shoots away completely and trim back any stems which are crossing. Prune on a dry day and use a sharp pair of secateurs. Make the cut a sloping one to avoid water settling on the cut surface.

Cut the shoots and branches to an outward-facing bud to try and achieve the goblet shape with a clutter-free central part. If the position of an outward-facing bud only occurs further down the stem to be pruned, prune to that point. Particular attention should be paid to keeping most of the centre of the plum tree free from branches. This helps the overall health of the tree by allowing free air circulation, thus avoiding fungal diseases.

When To Prune Your Plum Tree

Plum trees differ from most other fruit trees because they should only be pruned when fully growing. In the AU, the best time to prune your plum tree is in mid-June, never in winter when they are dormant. The reason is that pruning your plum tree when it is dormant will expose it to the risk of Silver Leaf disease and other fungal infections.

Strongly growing plum trees are more resistant to fungal infections. It’s also the case that Silver Leaf Disease spreads through spores that are far more common in the damp conditions in autumn and winter.

In general, any time from late spring to the end of July is the risk-free time to prune your plum tree.

There are two exceptions to this rule (there is always an exception or two!), and they are:

A newly bought one-year-old plum tree was planted in winter. The supplier of a new plum tree should have identified if they have sold you a one or a two-year-old plum tree. If not, see the two diagrams lower down this article to help you identify what age your tree is.

It is important to prune a one year plum tree as soon as possible to help it establish a good structure. At the same time, pruning in winter exposes the tree to fungal infections. With these two factors in mind, we recommend pruning a one-year-old tree in early March .

Prune on a dry day and use a sharp pair of secateurs. Make the cut a sloping one to avoid water settling on the cut surface. See pruning a one year tree below for more details.

Where an established plum tree suffers breakages of one or more branches (wind and weight of fruit are two common reasons), then it is best to prune back the broken branch to good solid wood immediately. The tree will suffer less if a branch has been cleanly cut compared to a breakage where the surface of the broken branch is open and ragged.

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