Most maple species do not like pruning, and they naturally grow very harmoniously and form well-proportioned crowns. However, even the most beautiful maple needs to be pruned, either because it overgrows the garden fence or to remove damaged branches. Unlike many other deciduous trees, this should not be done in spring, but at the beginning of autumn. You can find out why this is so and how to prune your maple here.
Is it necessary to prune a maple?
It is therefore by no means obligatory to prune a maple. Rather the opposite is the case: many tolerate severe pruning rather badly. Pruning will also have no positive effect on the growth, flowering or habit of your maple, as is often the case with other woody plants. Most species shine in all their glory even without this care measure. So you can let your maple grow without a guilty conscience. Pruning is only necessary in certain cases.
The right time
The sap flow of plants is the transport of water absorbed through the roots and the nutrients contained therein to the tips of the shoots. This process is responsible for sprouting and growth. In maples, this sap flow is comparatively strong, so that it literally drips out of the cuttings. Towards the end of summer, or at the beginning of autumn, a window of opportunity opens in which the sap pressure decreases. That is why this is the best time to prune a maple. Preferably choose a mild autumn day when it is dry but a little cloudy.
Pruning maple: This is how it’s done
Most species of the genus Acer can be pruned between late summer and early autumn. Two robust exceptions that tolerate pruning better than most other species are the field maple (Acer campestre) and the fire maple (A. ginnala). They also tolerate pruning into perennial wood.
On the other side of the pruning tolerance spectrum, however, are delicate ornamental maples such as the fan maple (A. palmatum): Here you should prune as little as possible and not in autumn, but in spring, shortly before the first leaves appear.
Of course, you can always remove deadwood from woody plants that do not tolerate pruning, such as maples, all year round without any problems. However, cut on a frost-free day to prevent splintering of the wood. This not only makes the maple look tidier, but also eliminates a source of danger in the garden – especially with larger maple trees such as the Norway maple (Acer platanoides), falling branches can quickly become a hazard. Always remove only the dead part, not the healthy wood. Also, do not leave any stumps.
Branches affected by pests or diseases should also be removed to preserve the health of the maple. Affected areas are cut back just into the healthy wood to completely remove the disease or pest in question.
Keeping an eye on the health of woody plants
A regular check of the woody plants in the garden is recommended in order to be able to detect disease or pest infestations in time. This also avoids having to cut back into the old wood later on – this is not good for many maple species and they often sprout again with difficulty.
In principle, however, maples are robust trees that remain healthy if they are in a suitable location. Too frequent or improper pruning can be the cause of problems, e.g. because fungal diseases can penetrate more easily.
If you have to use scissors because of disturbing shoots, you should remove them up to the base with a smooth cut – i.e. up to the next side or main shoot. If the branches are too long, for example, if they extend into the neighbour’s garden, do not cut them back to the old wood if possible, but cut them off early in the one-year-old wood. If shoots need to be shortened, cut at an angle of a few millimetres above a bud or a leaf node.
Thinning out the crown
If the crown grows too densely and branches shade each other, you can carry out a discreet thinning pruning in autumn. This may be necessary, for example, for the compact-growing globe maple (Acer platanoides ‘Globosum’). It is usually sufficient to remove all branches that grow across or inwards up to the branch ring.
Regulate growth height
It is a fallacy to think that the growth height of a maple can be regulated by uniformly cutting all shoots to the same height. A healthy maple will simply sprout again at the intersections of young shoots; and usually even shoot up all the faster. Instead, whole shoots that grow far out of the crown would have to be removed regularly. If you are still deciding which maple to plant in the garden and have little space, choose a small maple to avoid this problem (dwarf varieties such as Acer palmatum ‘Shaina’ or ‘Pixie’ remain particularly small).
Avoid broom growth
If thin shoot tips are cut back several times at any height, the so-called broom growth can be promoted. The maple may form many small new shoots that sprout from the cuttings like small brushwood brooms.
Pruning maple into a hedge shape
The field maple (Acer campestre) is one of the more robust species of its genus. For example, it can also be shaped into a hedge. It is also an exception to the autumn pruning rule. For an even shape, you should prune a field maple hedge twice a year; once between May and the end of June and a second time in mid-August to early September. In general, you can do less wrong here, as the field maple is quite hardy.
Cutting maple: The right tool
It is especially important to use clean and sharp tools for pruning woody plants such as maple. After all, cuts are always an entry point for diseases and pests. And the faster they can heal, the better. If you have used scissors to take back diseased shoots, it is even necessary to disinfect the scissors before working with them again. Even if larger branches have to be removed and a saw is used, for example, the cut should be smooth and not show any severe fraying.