Tony Dickerson answers your questions
Q What should we do with a large mature ash tree in our new garden? Michael Bland, Rugby, Warwickshire
Ash are large trees when fully grown, reaching 25m (82ft) or more in height and are usually unsuitable for most residential gardens. They don’t respond well to hard pruning, which is normally only recommended to remove damaged branches. However, a tree of this size will be beneficial to local wildlife so, where possible, it’s always better to try to preserve a mature tree. Whatever you do with the tree, check first that it’s not under a Tree Preservation Order (TPO), as fines for unapproved work are considerable. The tree officer of your local council can advise. Of the pruning options available, crown lifting is relatively straightforward. This involves removing the lower branches completely, which allows more light in. It also limits the number of pruning wounds, which could become points of infection, and will make a noticeable difference to the size of the tree in the long run. If possible, pruning should be carried out gradually over a few successive winters, starting with the worst-placed branches and taking them back to the main trunk; however, this often makes the process more expensive. Ensure you employ professional tree surgeons. The Arboricultural Association (tel: 01242 522152) can give details of suitably qualified contractors.
Crown thinning is your secondbest option. This involves removing some of the branches in the canopy to open up the tree, but exposes large pruning wounds. Simply trimming back all of the branches will just result in vigorous water shoots, spoiling the shape of the tree.
Although replacement seems drastic and will, in the short term, affect wildlife, it’s often sensible to remove a large tree from an urban setting before it becomes a potential problem.
Bear in mind that even if you do pay to have the crown lifted, you may still need to pay for the tree to be removed in the future. Consider the tree’s value in your garden, not just in terms of wildlife, but also aesthetically. Perhaps you could plant a smaller replacement now, giving it the chance to establish while you continue to enjoy the ash, and plan ahead for its removal.