The majority of deciduous trees are best pruned when dormant, this is around late autumn or winter. It is not advisable to prune in late winter or early spring as many trees bleed sap at this time of year. Trees are less likely to close pruning wounds at this time of year leaving them prone to infection.
There are exceptions to the deciduous trees rule including maple, horse chestnut, birch, walnut and cherry trees which all bleed extensively even towards the end of their dormant season. These trees are best pruned in mid-summer after new growth has matured.
Fruit trees should be pruned when they are dormant in winter. Dead, dying and diseased branches and branches that cross over each other should be removed. Branches which grow into the centre of the tree, should also be removed as this prevents sunlight reaching in.
The following are a list of reasons why pruning works may need to be carried out:
- Trees may be in physical contact with buildings, fences and other infrastructure.
- Trees may be growing close to or across a neighbour’s boundary.
- Trees may have branches that obstruct or overhang the public highway or a public right of way.
- Trees may be causing a ‘legal’ nuisance to an adjoining property.
- Large trees in a small garden may prevent the reasonable enjoyment of the property.
- Trees may be obscuring sightlines, access, signage and streetlights.
- Young trees may require formative pruning to improve crown shape and branch structure.
- Removal of hazards such as dead or diseased material, broken branches and storm damage to make a tree safe, or to re-shape a tree and balance the crown.
Pruning should only be carried out if it is deemed necessary to do so, since any cutting can potentially weaken a tree and each pruning wound exposes vulnerable tissues, which may be invaded by wood decaying organisms. Generally most trees which need pruning will require one, or a combination of the following techniques. Pruning should aim to remove no more than 15-20% of the crown at any one time.
This is the removal of a small portion of the secondary and small live branches throughout the crown. Thinning should provide a uniform density of foliage around an evenly spaced branch structure and reduces the density of the crown without altering the shape and form of the tree.
Thinning allows more light to pass through the crown, reduces wind resistance and can lessen the weight of heavy branches. Crown thinning includes crown cleaning- the removal of dead, dying, diseased, crossing, crowded and weakly attached branches of low vigour.
This is the removal of the lowest branches and preparing of lower branches for future removal. Crown lifting should avoid creating large wounds on the main trunk of older trees as these may take many years to heal. To avoid lack of balance after crown lifting the crown should be at least 2/3 of the total height of the tree.
Useful for allowing more light into a property. Provides clearance above roads, footpaths and smaller outbuildings such as sheds and garages.
This is the reduction of the crown of a tree, or the tree itself, whilst maintaining its natural shape and form as far as is practicable. The ends of the branches should be removed back to a suitable growing point and the diameter of the remaining branch should be at least a 1/3 of the diameter of the branch which is being removed.
Ideal for preventing branches contacting buildings, roofs and gutters. Removal of branches obstructing street lighting, overhead cables, signs and other infrastructure.
Pruning techniques for different groups
- A feathered tree such as a sorbus has an upright trunk and a balanced pattern of horizontal branches running from top to bottom.
- Each year, check for shoots growing at odd angles, extra shoots growing from the top of the main trunk, or basal shoots (strong shoots coming from the base which deprive the tree of nutrients).
- All of these shoots need to be removed.
- Young standards like cherry trees are trained in the same way, but the lowest branches are cut off until a clear trunk has formed.
- In the first year remove the lowest third of the tree’s branches, and shorten those in the middle third by half. Remove these latter branches in the following year.
- By the fifth year the trunk should be developed, so prune branches out from the tree’s crown to produce an open pattern of branches.
- Some trees, especially those grafted onto special rootstocks, produce suckers, which are secondary shoots growing from the roots. As these may exhaust the tree, pull each one up while it’s still small, after first exposing the point where it joins the root.
- Pollarding and coppicing are traditional techniques that are used for timber production, but they’re also useful when pruning ornamentals grown for decorative bark or leaves. It can also be used for keeping trees trimmed to a fixed height.
- Coppicing involves pruning growth back to, or near, ground level in winter and is used for coloured willow and hazel varieties.
- The same trees respond to pollarding, which is a taller version of coppicing with growth cut back to a short trunk.
- Eucalyptus and lime are often pollarded every two to three years to maintain a compact size or smaller foliage. Remember to feed your tree after pruning to encourage plenty of new young growth.
- Most standard conifers develop without the need for pruning, but you may need to prune out any damaged or distorted growth.
- This is best undertaken in autumn or winter. If a tree forms two stems, select the strongest, most upright shoot and cut out the competitor at its base.
- You should remove any plain green shoots which appear on variegated conifers, and any abnormally-shaped shoots on dwarf and prostrate conifers.
- Patches of dead or brown foliage need to be taken out and any gaps can be disguised by tying nearby shoots together so they grow across the pruned area.
Conifers require little or no regular pruning except the removal of dead or diseased branches in late summer.