Pruning Hedges and Trimming Hedges
Pruning Hedges and Trimming Hedges
Hedging plants fall into three categories:
- those with a naturally upright growth habit which must be encouraged to thicken up at their base;
- those with a naturally low and bushy growth habit which must be encouraged to gain height and density at their top;
- and the conifers which need only minimal training to establish their shape.
Upright Hedging Plants
Upright plants, such as privet, hawthorn, snowberry and blackthorn, must be cut back hard throughout their early years to promote strong basal growth. Left inadequately pruned, these plants become bare at their base.
At planting time they should be cut back to about 15cm (6in) from the ground. During the following summer lightly trim all branches to encourage active growth of as many new shoots as possible. The cutting pattern must reflect the desired final shape of the hedge. Cut back new growths again by half during the second winter to make them bush still further. At the same time, prune back all other branches close to the main structural stems. Above all, discourage the leaders from reaching their final height too quickly.
Pruning hedges during the next year will depend on how dense the hedge has become. If further thickening is desired, repeat the winteronce more as for year two. If the density is satisfactory, trimming in subsequent years can be restricted to the growing season. The frequency of trimming during any one year will depend on the cultural conditions and on the species concerned, but every six to eight weeks from mid to late spring through to about early autumn is the usual requirement. Aim to keep the plants neat and within the confines of the desired overall hedge shape, and ensure that the sides of the hedge taper.
Bushy Hedging Plants
Bushy, such as beech, hazel and hornbeam, need less severe pruning in the early formative years.
At planting time, trim back the major side branches and the leader by about one-third. Allow the plants to develop naturally during the first summer. During the second winter, repeat the pruning as for year one. Eliminate all straggly growth.
As with upright hedge plants, trim only during the growing season in every subsequent year, maintaining a tapered outline. Preferably, trim twice in each season — in early summer, then again in late summer or very early Autumn. The early summer trim can be ignored if you wish. Coniferous hedging plants, such as Lawson and Leyland cypresses, and Western red cedar, need rather different treatment. The leader must not be removed at planting time. Slightly trim only the straggly side branches to promote the formation of well-balanced laterals.
The main stem of most young conifers is not rigid enough to withstand strong winds or snow loads and must therefore be staked and tied loosely but securely. As the conifers get older and stronger, remove the stakes.
Allow the leader to develop unhindered until it reaches the desired final height. During the second and subsequent years after planting, trim only the side branches during the growing season. Most species require only one trim in late summer If vigorous species become too overgrown by mid summer you can overcome this in subsequent years by giving an extra trim in early summer. Flowering formal hedges, such as forsythia, should be trimmed during the growing season immediately after thehave faded. A second trim in late summer may be necessary to maintain a neat shape, but do not remove too much growth or next year’s developing flower buds will be lost.
Flowering Informal Hedges
Flowering informal hedges, such as berberis, should be pruned according to the age of wood on which they flower. If they flower on old wood, trim to shape immediately after flowering; if they flower on the current season’s wood, trim in early spring.
Fruiting Hedging Plants
Fruiting hedging plants, which develop attractive fruits after the flowers have faded, such asand berberis, should have their young growth trimmed in mid to late summer, leaving most of the fruiting wood intact. This selective trimming must be done with secateurs. Alternatively, leave trimming until the fruits have gone.