Most hedges in the countryside were originally planted to control stock or mark boundaries, with urban and garden hedges planted for privacy and shelter. However, hedges have other uses and advantages and form an important habitat, especially valuable in otherwise intensively farmed areas. Hedges have a high landscape value, being a major element in the appeal of British lowland scenery.
However, although multi-purpose, many hedges have one particular use which is of prime importance, and which will help determine the choice of species. As well as use, the other important factors to be taken into account are those relating to the site. These include the soil type, drainage, exposure to wind, altitude and the occurrence of late spring frosts. Possible damage from browsing stock or wild animals needs to be taken into account, as well as possible vandalism or theft of young plants. Hedging species also vary in their initial purchase cost, which is likely to be a factor. See table 5.2 here.
The choice of species is most easily made by looking at hedges in the vicinity of the new site, which will indicate which species should thrive given the local climate and soils. In some areas particular species are traditionally used for hedging, and are thus well proven as successful in that area.
This handbook is concerned with native or long-established woody species, but there are many introduced species which may be suitable for garden hedges or hedges in urban areas. For further information, refer to a book on garden hedges, such as Hedges and Screens (Pollock, M, 1994).
Note that nearly all the species described here will become trees if left untrimmed and not laid. Most species have to be trimmed to encourage the dense, compact growth that characterises a hedge.
When planning a new hedge, remember to allow room for the hedge to grow. A mature hedge of hawthorn planted in a single line will spread to cover a width of approximately 6ft (2m). A double line hedge may take up as much as 10ft (3m). See the diagram below. If the hedge must be narrower than this, one of the species used for garden hedging, which are slower growing and so require less trimming may be suitable. Note though that many garden hedge plants are poisonous if eaten by farm stock.
Stockproof Hedges
Most hedges were originally planted for stock control, in the time before the advent of cheap wire fencing. The craft of hedge laying developed as a method of keeping hedges stockproof, at the same time as rejuvenating the hedge to keep growth young, dense and bushy. In spite of many hedges also now being fenced, being stockproof remains an important quality, and with it come other benefits. These include being an effective windbreak, a barrier to people, and a dense, continuous habitat for wildlife. Laying greatly prolongs the life of the hedge, and may maintain a genetic pool going back over the centuries. Uniform growth is important for a stockproof hedge, so that it has no weak points where stock can get through, and so that the hedge can be trimmed and laid effectively. This often means using a single species.
The qualities necessary of species for a stockproof hedge are as follows:
- able to withstand hard cutting by producing strong growth that is compact, dense and difficult for animals to penetrate. Dense, leafy growth at the base is particularly important. Thorny growth is a further deterrent.
- unpalatable to stock.
- hardy to wind and frost.
- quick growing, both to establish when newly planted, and to regrow quickly when laid.
- long lived.
- adaptable to a variety of soil conditions.
- free of serious diseases or insect attack.
- easy to propagate and so cheap to produce.
Farm hedges should never include species which can be poisonous to stock (see table 5.2). Species that sucker into adjacent ground can also be a problem.
Throughout most of Britain, hawthorn is the best hedging plant on nearly all counts, and has long been used for this purpose. Blackthorn is also suitable, though its suckering habit may be a problem. Some species which are second rate on good sites come into their own under more extreme soils and climatic conditions.
Boundary Hedges
Hedges may be planted to mark the boundaries of land ownership. On farmland, stock control is an additional factor, whereas for estates and gardens, privacy and being proof against people are important. In the past, boundary hedges on farmland were often made more significant and easily recognisable by being set on banks, or by including particular species, notably holly. Boundary hedges may need to be kept trimmed, in order to stop them encroaching on neighbouring land, including roads and other public areas.
Shelter Hedges
All hedges give shelter which can be important for stock, people, crops and garden plants. However, in some areas hedges are planted specifically for the shelter they give. These include shelter hedges and windbreaks on the flat areas such as the Fens, where they help prevent soil blow. Fruit-growing areas often have shelter hedges, as do the hop gardens of Kent. In exposed areas of the West, shelter is increased by planting shrubs on stone-faced banks, which are themselves referred to as ‘hedges’. On Exmoor, the tall beech hedges give shelter from the south-west winds.
Species for shelter hedges need to be tough and hardy to withstand the exposure, and preferably fast growing. Sometimes fast-growing species such as willow, alder, or the introduced Leyland cypress (Cupressocyparis leylandii) are used as initial shelter, to allow slower-growing native broadleaves to allow to establish in their lee. The shelter hedge can then be removed when the more desirable species are established.
‘Wildlife’ Hedges
These are hedges planted mainly for their wildlife value, where their use in controlling stock or people is not significant. Species may be chosen because of their value for butterflies, birds or other organisms, rather than for their ability to produce dense, compact growth. However, when choosing the species, a decision needs to be made as to whether the hedge is to be maintained by trimming and occasional laying, or whether it is to be allowed to grow more freely, in which case it will form a line of shrubs and trees for which sufficient space must be allowed for growth. The flowers and fruit of the hedgerow are important factors in its value for wildlife, and the timing of any trimming should take this into account. Many of the species which are valuable in a wildlife hedge, such as elder, bramble and dog rose are considered as weeds in a stockproof hedge. The management of the adjacent field margin is also important in determining the wildlife value of the hedge.
Screening Hedges
Hedges may be planted to screen farm buildings, factories, caravan sites and other developments. It is tempting to go for fast growing species, but a much better criteria is to choose those species already common in the locality. Not only are they proven to be successful, but when grown, they will blend in with the surrounding landscape, rather than sticking out as an eyesore to equal the one they obscure. Leyland cypress in particular has been much mis-planted in the past for screening, along with other introduced conifers. The siting of screening hedges needs to be made carefully. It may be possible to screen an eyesore by planting hedges or trees nearer the point from which it is viewed, rather than trying to plant a taller screen close to the eyesore.
Hedges for privacy
These are mainly hedges to give privacy to gardens, homes, schools and other sites. Tall, dense evergreen hedges also have the benefit of filtering noise and dust, discouraging intruders, providing shelter, and being a habitat for garden birds, small mammals and invertebrates. Interestingly, the native British flora included the perfect plants for the classic garden hedge: yew, box and privet. However, all are unsuitable for stock hedges: yew and box because they are poisonous, and privet because of its weak growth.
The introduced garden privet (Ligustrum ovalifolium) has mainly superseded the semi-evergreen native privet (Ligustrum vulgare) for garden use, but the native privet was long used for garden hedges, and occasionally mixed with other species in farm hedges. Yew and box are slow growing, which is seen as a disadvantage when planting a new hedge, but is a distinct advantage when maintaining an established hedge. Beech and hornbeam make good garden hedges, as they produce neat growth when trimmed, and hold their dead leaves over winter to give privacy and shelter. Most of the other native species are too vigorous or thorny or do not produce sufficiently dense growth to make good garden hedges.
