What is pollarding
Pollarding is the technique of regularly pruning trees or shrubs back to a trunk to form a head of branches. The trunk height can vary, with around 1.5 to 3m usual in a garden situation. Pollarding is done for several reasons: to restrict growth of a tree in a confined space, to create a formal shape, to encourage the production of stems with more colourful leaves and decorative bark, both of which are brighter on the young, vigorous growth that hard pruning stimulates, and lastly to produce larger than usual leaves. Pollarded trees are a common sight in cities and particularly in many European countries. The practice of pollarding should be done as a form of training from when the tree is young and should not be used as a means of reducing growth on an older tree.
Pollarding is similar to coppicing. The difference between the two is that coppicing involves cutting a tree or shrub back to a stump at ground level, whereas a pollarded tree has a trunk that broadens with age and a head with stubs of branches from which new shoots grow each year. In traditional woodland management, both techniques were used for practical reasons, such as firewood production and to harvest straight stems for fencing.
What to pollard in your garden
Trees with decorative foliage that produce much larger leaves or more intense colouring when pollarded include Catalpa x erubescens ‘Purpurea’, Eucalyptus species, especially Eucalyptus gunnii, Paulownia tomentosa, and tulip tree (Liriodendron).
Shrubs and trees that benefit from pollarding to produce coloured stems include many willows (Salix) including Salix alba ‘Britzensis’ and Salix alba var. vitellina, and Tilia cordata ‘Winter Orange’.
Trees that have a formal appearance when pollarded, or are pollarded to restrict growth where space is limited include London plane (Platanus x hispanica) and lime trees (Tilia).
When to pollard your tree
You should pollard your tree every year when the tree is dormant, in late winter or very early spring.
How to pollard
Start by planting a young tree with a single stem. Once the trunk or stem has reached the height you want, cut back the branches in late winter or early spring. Select three to five branches to keep as the basic framework and cut these back almost to the trunk. This hard pruning stimulates the growth of many slender shoots from each stump.
In future years, repeat the process either annually or every second year, cutting back all stems to within 1-2cm of last year’s growth, close to the pollarded head of the tree. Take care not to damage the bark on the head or stem, as wounds can allow disease into the plant.
Depending on the size of stems, either use secateurs, loppers or a pruning saw. Ensure tools are sharp so they make clean cuts and don’t tear the bark.
Pollarding: problem solving
An abundance of shoots is encouraged by pollarding and if too much growth is produced, thin out overcrowded stems in spring or summer. First, remove the weakest shoots, any that look unhealthy, and those which cross as they’ll rub on each other and create wounds that could allow disease to enter. Then, thin out any stems that still look overcrowded.
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Any shoots that grow from the trunk below the pollarded head should be taken off as soon as they appear, which can be any time during the growing season. Ideally remove by snapping off, rather than cutting which can encourage even more shoots to develop.
Avoid pollarding older, established trees as this can cause disease or decay, leading to loss of a tree.