How to prune a tree

Unlike trimming a fruit tree or hedge, pruning a tree often involves removing larger branches. It's important to ensure that your tree really does need pruning as this is a fairly traumatic process for the tree. Here are the main reasons why you might need to prune a tree:

• To follow certain rules; remember that home owners do have the right to cut any tree branches that overhang their garden.

• To clear branches overhanging buildings or electric cables when the crown has spread too far.

• To cut off any dead wood before it falls off the tree.

• To rebalance an uneven shape (after a storm, for example).

• To decrease the size of a tree that is exposed to strong winds.

Steps

1. Choosing the right time to prune

2. Picking the right branches to prune

3. Cutting branches precisely and cleanly

Required skills 

Ideally, you should have a good idea of the anatomy and physiology of trees: you should be able to distinguish a healthy branch from a sick one and be able to spot suckers. It's also a good idea to have a good knowledge of the morphology of your particular trees in order to prune in line with their natural silhouette.

Using small tools like saws or secateurs shouldn't be too tricky but bear in mind that larger branches may require the use of a chainsaw. The job will also get tougher if you have to work from a stepladder; in this case, you might want to hire the services of a tree-cutting professional.

Time required

1 to 2 hours, depending on the size of the tree

Number of people required

1 person

Tools and equipment

• Secateurs

• Branch cutters or electric pruners

• Tree loppers

• Stepladder

• Pruning saw

• Chainsaw

• Spatula and pruning sealer

Personal protective equipment (PPE)

• Protective gloves

• Safety shoes

• Safety goggles

• Ear defenders

• Hard hat with chinstrap or forest helmet

• Tree surgeons sleeves

• Any other tree-cutting equipment you may need (e.g. ropes, harness, etc.)

Please note: this is a non-exhaustive list; be sure to match your personal protective equipment to the job at hand. 

Picking the right time to prune your tree will help your tree to heal quicker and inflict as little damage as possible. Pruning is traditionally done while the tree is dormant. The process will be easier when the tree doesn't have any leaves and you'll be able to better identify branches.

The best time of all to prune is the end of spring or the start of summer as this is when trees seem to heal more quickly. Avoid pruning at the start of spring as your cuts may cause the tree to lose excessive amounts of sap. Additionally, it's best to be sure that the frost has definitely finished for the season.

Ideally, you should prune several times over a period of a few years to avoid pruning a lot in one go as this is not good for the tree.  The best way to proceed is to plan ahead and cut branches while they're still young so you only have to prune small branches.

• Remove any branches that are growing from the roots and get rid of any suckers that have appeared on the trunk or under scaffold branches.

• Remove any dead or broken branches.

• Remove any branches facing the wrong direction (towards the ground or centre) or any crossing branches.

• Thin out the centre of the crown as required to allow the light to enter.

• Trim down any lateral branches that have grown too long to maintain the natural shape of the tree.

• Cut any secondary branches growing upwards but keep the connecting branches.

• Trim down any top branches as required to stop your tree growing too tall.

Cutting a large branch in 3 steps 

Any branches measuring over 4 cm in diameter should be cut in three stages. This technique allows you to ensure that the branch doesn't fall of its own accord and end up tearing part of the bark below. Here are the steps to follow:

1. Around 20 cm from the trunk or supporting branch, trace a line with a saw underneath the branch you want to cut. Using a chainsaw or prune saw depending on the side of the branch, cut around a third of the way in.

2. Saw the branch from underneath a few centimetres below your first line; the branch should break, leaving behind a stump.

3. Cut the stump at the correct angle. You will have to cut diagonally but make sure not to cut too close to the trunk. This will allow woundwood to form around the cut. By following this technique, you'll avoid creating a stub.

 Pruning sealer: a controversial practice

It generally used to be recommended to apply pruning sealer to any cut over 2 cm. However, many do not advise this approach as this layer is thought to trap in pathogenic micro-organisms, heat and moisture which creates the ideal environment for fungi. That said, pruning sealer does tend to be used on fruit trees to tackle disease and is recommended for sensitive trees such as lime trees, poplars and cherry trees.

1. Always work with very sharp tools in order to make neat, clean and tear-free cuts. Disinfect your tools between trees using alcohol or bleach.

2. Pruning should always involve a lot of forward-planning to ensure your tree maintains an even silhouette.

3. When cutting larger branches, you may need to attach a rope to the branch so another person on the ground can guide its fall.