Initial pruning and training
If the transplants are well branched avoid cutting them back. Otherwise, for the first two years after planting, concentrate on shortening the longer shoots and just tipping back shorter ones to encourage branching and dense growth without much loss in height. Trim in the second week of August.
From the third year onwards, trim the sides of the hedge, aiming for a flat-topped A-shape (in cross section) to ensure that sunlight reaches the top and bottom equally. Aim for a width of about 1m (3¼ft) at the base, tapering upwards to the desired height.
Pruning established hedges
Once established trim regularly in August. This late summer trimming allows the hedge to retain its recent flush of new leaves over the winter in a brown, autumnal state, providing year-round screening. If you are too late for August pruning wait until spring.
To renovate an overgrown beech hedge, cut it back hard in February while still dormant but delay if the weather is very cold. If the height needs reducing by 50 percent or more, then stagger pruning over two seasons rather than doing it all at once. If the sides need drastic reduction, then do one side and the top in the first year, leaving the other side to the second year. However, where recovery is poor, with little new growth, delay completion of cutting back for a further twelve months.
To obtain accurate levels and angles when renovating, use garden lines stretched tautly between sturdy canes or stakes driven in at the ends and at intervals along the hedge. Cut so that the sides slope slightly inwards; the hedge narrowing a little from base to apex. This encourages lower growth. Use a pruning saw for cutting thicker growths. It is not necessary to apply any wound treatment to pruning cuts. Mulch and feed after renovation, to encourage regrowth. A general purpose fertiliser such as Growmore is ideal, applied along both sides of the hedge where possible. Water thoroughly from time to time during any dry periods in the first growing season following cutting back.