Dear Sibe,

I have a birch tree in my front garden that is as tall as I want it to be, about 22ft (6.7m)with a clear trunk of about 10ft (3m). What advice would you give about pruning/lopping it back so that I can control its height without sacrificing a reasonably shaped crown?

Thanks
Dave

Our gardens expert replies

Hello Dave,

Assuming your birch tree is the common silver birch, Betula pendula, then this could grow as high as 35in (9m) or more at maturity. It would be possible to control the height of the tree by regular pruning but whether this results in a reasonably shaped crown depends on the care you take in removing branches. The worst thing you could do is to cut off the ends of the branches - ie trimming. This would merely result in new vigorous growths towards the cut ends which would always look like... cut ends. The best approach would be to remove complete branchlets quite close to the stem they join, leaving an elbow of no more than half an inch. New growth would then be channelled to the existing branch network which would, unfortunately, grow more vigorously and require pruning at a later date.

Provided you are prepared to prune regularly it should be reasonably successful, at least for a number of years. It would be better to prune in the summer months rather than winter, though you could take advantage of the leafless state of the tree at this time of the year to plan where you intend cutting, as it may be difficult to see later in the year. If you can gain access to the upper parts of the tree you could tie on pieces of coloured wool, for example, marking places to cut. The reason for not cutting until the summer months is that the spurt of spring growth will be dissipated through the existing network of branches rather than being concentrated in new growth points which would break through following a winter prune.

Birch trees can look extremely attractive for many years and I think you are taking the right approach in enjoying this tree as long as possible. Remember, though, that when it is approaching the end of its useful life, you can always plant a younger sapling birch where it can ultimately take over once your existing tree is destined for removal.

For additional advice see Pruning Tips.

Good luck with it,
Sibe