When is the best time of year to prune an overgrown beech hedge? Ours is too high and wide and is beginning to block a pathway, but I’m worried about damaging it if I cut it back too hard. E Gilligan, Waterford

Beech (Fagus sylvatica) is very popular with Irish gardeners as it makes an exceptionally handsome and robust garden hedge. Although it’s a deciduous species, it also holds on to its faded autumn leaves when grown for hedging (unlike beech trees), only shedding them in late spring when the new, fresh foliage emerges. In this way it also provides great shelter throughout the year.

But as you’ve discovered, an established beech hedge does need to be carefully trimmed every year to keep it in good shape. This is best done in mid-August, using a sharp shears or hedge trimmers to neatly cut back the sides and top, and making sure that you cut back enough to prevent middle-aged spread. Ideally the sides should be slightly tapered, so that they slope slightly outwards from the top (think A-shaped, but with a flat top). This encourages healthy growth and also makes the hedge less vulnerable to damage from heavy snowfalls. A bottom width of 1m-1.2m is generally advised.

In the case of an overgrown beech hedge such as yours, you’re right to be cautious, as overly harsh pruning can shock the plants, especially if carried out at the wrong time of year. In this case, what’s known as remedial pruning is required, which should be carried out on a phased basis over a couple of years. This is best done in February while the plants are dormant. In the first year, cut back the top of the hedge as well as one of the sides to the size required. If your hedge takes this in its stride, then the following spring cut back the remaining side. But postpone the second phase of this remedial pruning for a further year if your hedge shows any signs of struggling to recover from being harshly pruned. From then on, an annual trim in August is all that’s required to keep it in shape.