Pruning a Japanese maple
The Japanese maple or Acer palmatum
The Japanese maple or Acer palmatum is a shrub or tree that comes in a range of magnificent colours, from light green through to dark red. This hugely popular tree is the perfect choice to give your garden the wow factor and unmissable if you're following the latest trends closely.
The Acer originates from Europe and North America, where they grow to full size. The Acer palmatum is the smaller version of this tree or shrub and comes from Japan, where its size makes it the perfect choice for gardens and patios. It is fully winter hardy and requires very little attention. In other words, it is no delicate flower! The only exception to this is periods of absolute drought, when you will need to water the tree or shrub several times a week.
The Japanese maple grows slowly, so does not need frequent pruning. Its sap also flows strongly between February and June, which means it can bleed to death if you prune it at the wrong time of year.
Read on to find out when to prune the Japanese maple and the best way to go about it.
Pruning in the spring
The Japanese maple can sometimes suffer from dieback, often caused because the soil contains too little or the wrong nutrition. The initial treatment is to administer feed. The Japanese maple is an acid-loving plant, so it prefers an acidic soil. The next step is to get rid of affected branches, ideally just before buds appear, when you should prune back to living wood. Make sure that you don't go any further than that; sap rises in maples from early in the winter, so trees pruned in the spring could bleed to death. Of course, that doesn't affect any deadwood that you remove as it no longer contains any sap.
Pruning in the summer
By nature, the Japanese maple grows relatively evenly, so some need no pruning at all, unless branches die back or you want to change its shape. If you want to maintain a compact shape, you can trim the plant in the summer; ideally at the end of June or start of July, when the flow of sap tails off again. Cut the branches back depending on the size of the plant and what you want to achieve. We recommend that you reassess your progress regularly, and always aim to maintain a natural shape. It's important that you trim evenly across the plant, starting at the end of each branch and looking at how many twigs it has. Always cut the branch back to just above a new twig, as this will take on the job of the old one. Make sure that you don't create any big holes in the plant and never simply cut bare wood away. This will create shoots that are difficult to keep under control. Finally, you can also cut away deadwood in the summer, but always make sure that you cut back to living wood.
Pruning in the autumn
Trees with long branches help to create a cosy atmosphere in your garden, but if you do want to cut your Japanese maple back, we recommend that you remove the lowest branches; ideally between October and December. The best way to deal with larger thick branches is to saw them off but don't remove them right up to the tree trunk; this will protect the branch collar and be better for the tree. We recommend sawing thick branches off in stages, to prevent additional damage to the tree if the last section of branch tears off during sewing. Always start with a vigorous cut on the underside of the branch. For very thick branches, start around 10 cm from the trunk; for thinner branches, you can reduce this to around 5 cm. Once you've sawn the branch off, you will be left with a stump, which you should then remove as well. Remember to stay far enough away from the trunk, so you don't damage the branch collar. We recommend applying a wound treatment product to fresh saw cuts.
You can prune trees and shrubs with secateurs or pruning knives for the small branches. Use a saw for thicker branches or stumps. Always make sure that your tools are clean and as sharp as possible, to prevent cuts and infections. If you do leave cut marks, however, apply a wound treatment product to the plant to prevent disease and limit the loss of sap.