WHEN TO PRUNE YOUR OVERGROWN PLUM TREE?

The answer to that question is simple, prune your plum tree when it’s growing strongly and for established plum trees early June to mid July is the best time. Do not prune it in winter /spring because the risk of fungal infection is high and don’t prune it in autumn because the leaves are needed by the tree to transfer nutrients to it as they die.

THE PRINCIPLES BEHIND PRUNING ESTABLISHED PLUM TREES

Established plum trees are all very different in shape, size and structure which means that one set of absolute rules can’t be applied to them all. However a set of basic easy to understand principles can be used to apply to almost all overgrown plum tree which amateur gardeners can use to guide them through the process.

We recommend that you take a four step approach before you even begin to prune an established plum tree. The reason for this is that although plum trees withstand neglect better than many fruit trees they can be put at risk from bacterial and other infections if you don’t carry out pruning correctly. Incorrect pruning techniques are far more liable to damage the tree compared to lopping off the wrong branch using good pruning techniques. Those steps are:

• Have the correct tools. A sharp pair of secateurs can be used to cut away smaller stems. For larger stems and branches use a pruning saw. If you are pruning more than one tree, disinfect the tools between trees. One measure of bleach to ten measures of water should be sufficient.
• Use a safe set of steps / ladder to reach branches higher up. If you are not confident using a set of steps or ladder, get someone else to do the job for you.
• Decide a means of getting rid of the pruned stems and branches. Often, the sheer volume of branches and stems can be a problem, be sure you know where they can be disposed of  / burnt.
• Read our guidelines on pruning techniques for plum trees at the end of this page to help you inflict the least possible damage possible on your plum tree when you prune it. This is especially important if you plan to remove any sizeable branches.

Now read through the guidelines below, then go outside and take a good, long look at your plum tree. Decide how best you think it can be pruned and then come back and read through the guidelines again before doing any of the pruning. The basic principles are:

• If significant pruning is required spread it over two or three years.
• Remove dead, damaged and diseased branches (the three Ds) first. They contribute nothing to healthy growth of the tree and are sites for bacterial and fungal infections to enter. You need to cut back to good, clean and healthy wood, anything less is pointless.
• Prune away any crossing branches. If they rub together the bark will be damaged and infections will enter the wood.
• Thin out the centre of the tree. Ideally, the main stem should have three (maximum four) main branches coming from it and they should spread outwards not inwards. If you have more than this then reduce the number to three or four. This may involve cutting away a couple of large branches but in the end it’s for the best. Remove some side branches / stems which grow in the centre of the tree.
• When pruning at this stage, try to maintain the “balance” of the tree. By this we mean keep the major branches spaced roughly evenly around the tree. This is sometimes difficult to achieve but just do your best. The tree will, of its own accord, balance its own growth out over a year or so.
• Prune lower branches so that main stems and branches which turn downwards are cut to be at least parallel with ground, preferably growing upwards and outwards.
• If the tree is excessively tall, prune a third of the height to bring fruit production lower down.

PRUNING TECHNIQUES FOR PLUM TREES

This section explains how to prune a branch, the same rules apply to plum trees and other fruit trees. The principle is to avoid damaging the collar of the branch and to make a clean cut which doesn’t tear the bark. The picture below illustrates the three steps.

STEP 1
Cut a notch about 3cm deep into the underside of the branch. This will stop the branch tearing under the weight of the branch as you make cut 2.

STEP 2
Cut downwards (in the direction of the arrow) through the branch trying to support it as you cut.

STEP 3
The final cut should be made as near to the collar of the branch without cutting into the collar.

PRUNING WATER SPROUTS

Water sprouts are quick growing shoots which grow straight upwards. They often appear on a plum tree when it has been hard pruned the previous year. They will not produce plums and simply sap the strength of the tree for no real purpose. If allowed to grow unpruned they will quickly block out light and reduce beneficial air circulation in the centre of the tree.

Prune them as close to the main branch / trunk as possible using a sharp pair of secateurs. If you keep on top of this task they will stop growing after a few months. Do this when the plum tree is in full growth, any time from early June to early August. It is best done on a dry dry to reduce the risk of infection.