When a tree has outgrown its space or started causing concern, pruning is often the first solution people think of.
But not all tree work is the same. Two terms that are often confused are pollarding and crown reduction, yet they are very different techniques with different purposes, appearances and long-term effects on the tree.
Here is everything you should know about the differences between tree pollarding and crown reduction.
What is crown reduction?
Crown reduction is the selective reduction of a tree’s height and spread by cutting back branches to suitable lateral growth points.
The aim is to make the tree smaller while keeping its natural shape intact. A correctly reduced tree should look like a smaller version of itself, not like it has been hacked away.
Every cut is made to a lateral branch that’s large enough to take over as the new growing tip, and cuts are made at the correct angle to the branch collar so the tree can seal the wound efficiently.
The result is a tree that retains its form, continues to grow, and doesn’t produce the clusters of weak watersprout growth that poorly carried out work tends to generate.
Crown reduction is commonly used where a tree has grown too large for its setting. This could mean the tree is shading a neighbouring property, growing too close to a building, or simply outgrowing a garden it was planted in decades ago.
It’s also used to reduce wind resistance on trees in exposed positions, and as part of managing the long-term health of trees that have become structurally unbalanced.
What is tree pollarding?
Pollarding is the removal of all branches above a fixed point on the main stem or scaffold branches, leaving a framework of stubs called a pollard head.
New growth shoots vigorously from these points, and the process is repeated on a regular cycle, typically every one to three years depending on the species and growth rate.
Unlike crown reduction, pollarding doesn’t try to preserve the tree’s natural form. It replaces it with a managed form.
A pollarded tree looks quite different from an unpollarded one, and over time the pollard head develops a characteristic knobbly structure at the cut points.
The technique has been used in Britain since Roman times, originally to produce a regular supply of straight rods from willows, ash, and lime without killing the tree.
In a modern context, it’s used to keep fast-growing trees at a fixed manageable height, to prevent them from encroaching on overhead lines or adjacent buildings, or to produce the dense seasonal stem colour effect on certain willows and dogwoods.
Which technique is right for your tree?
For most trees in a domestic garden, crown reduction is the more appropriate choice.
It reduces size and manages the tree while keeping it looking like a tree.
The range of species it can be applied to is broad, the ongoing commitment is lower, and the result is generally more in keeping with a garden setting.
Pollarding is the better option when the goal is to keep a fast-growing tree at a fixed height indefinitely, when the species is well suited to the technique, or when a tree has already been pollarded and the cycle needs to continue.
Starting a new pollard on a mature tree that has never been pollarded before is a more significant intervention and should always be discussed with a qualified arborist first.
The species you’re dealing with makes a big difference.
Willows, limes, London planes, poplars, and sycamores respond well to pollarding. Conifers, most oaks, ornamental cherries, magnolias, and many garden focal trees do not.
Crown reduction can be applied to most of these more sensitively where size management is needed.
When to carry out crown reduction or pollarding?
Late winter or early spring is the preferred window for most deciduous trees, for both techniques.
The tree is dormant, which means the wound is exposed for the shortest time before new growth begins to cover it, and the bare canopy makes it easier to see the structure clearly and make considered cuts.
There are exceptions.
Prunus species (ornamental cherries, plums, and related trees) are better dealt with in summer, when the risk of silver leaf disease spreading through fresh wounds is lower. Birch and maple bleed sap heavily in late winter and are better tackled in late summer once sap flow has reduced.
For pollarding, getting the timing right is particularly worth attending to, since the whole point is to give the tree a full growing season to produce vigorous regrowth from the pollard head.
For trees with a Tree Preservation Order or in a Conservation Area, timing is secondary to getting the necessary consent in place before any work starts. TPO applications take time, and starting without consent risks prosecution and an unlimited fine regardless of how well the work was carried out.
When to call a professional tree surgeon
Small trees at low height can be managed by a competent gardener who understands what they’re doing. Most crown reduction and all pollarding on trees above head height should be left to a qualified tree surgeon.
The risk with doing it yourself isn’t just physical safety, though working at height with a chainsaw carries serious risks both to the tree to your persons.
If you are ever unsure how a tree should be pruned, it is always best to seek advice from a professional arborist or qualified tree surgeon.
At GGM Landscaping, we have decades of experience in tree care and working at height. We hold City & Guilds NPTC qualifications, and all associated tree work is carried out in accordance with BS 3998.
If you need expert advice, contact our tree surgery team for an honest, independent assessment of what your trees actually need before any work is carried out.
Get in touch with our team on 07946 322717 to book your free consultation.