Guide to Garden Hedging

A hedge can be one of the most prominent features of a garden, yet few amateur gardeners seem to appreciate the great variety of hedging plants that is available or give much thought to which of many possible roles their hedges are intended to play. A hedge can mark a boundary or be used to divide a garden into separate areas. If it is reasonably dense and high it will offer not only privacy but shelter from wind – or a screen to hide a compost heap, dustbins, or other potential eyesores. It can act as a backdrop to beds and borders or, more interestingly, it can provide colour in its own right by way of flowers, foliage, and berries. For these and other reasons, then, you should have a pretty clear idea of the overall design of your garden, including the larger permanent plantings, before you decide which hedging plants to use. For example, if the main area in front of a hedge will be put down to grass, it would be a pity to plant the kind of hedge that will also be permanently green. On the other hand, a hedge in full flower is likely to be merely distracting if it is sited immediately behind border plants in bloom.

If you have a small garden, of course, you must decide first if you have enough space to accommodate a hedge at all, rather than a fence or a wall; your hedging plant must either have an essentially vertical habit of growth or stand being clipped to prevent it encroaching too far into the garden. Only a large garden can comfortably accommodate a lax, informal screen; and, incidentally, a tall screen that looked impressive in a large plot might well be claustrophobic in a small one. Speed of growth may be important if you have a new garden and need to provide a screen as quickly as possible; but remember that quick growth will involve you in more frequent clipping once the screen has reached the required size. You will save yourself a great deal of labour in the future if you are prepared to wait three or four seasons for your hedge to develop, rather than insist on maximum vigour of growth in the early stages. Some of the traditional hedging plants, such as holly and box, are not as slow-growing as many people believe (though yew, perhaps the finest of all, is very slow -and very expensive). As long as you prepare the site properly before planting and help the plants to become established, they will soon make a handsome screen.

Preparation of the site involves digging a trench about 900 mm (3-1/4ft) wide and 600 mm (2 ft) deep where the hedge is to be sited and working in plenty of well-rotted manure or garden compost. If neither of these is available, use leaf mould or peat instead, and fork a dressing of general fertiliser into the soil to provide food for the young plants. Be sure to buy only plants that are bushy and short-jointed and have roots that are firm and moist. Deciduous species should be planted in the dormant period between October and March in ground prepared up to six months before; evergreens are planted in April or May in ground prepared the previous autumn. The first clipping should not be made until at least a year after planting.

Selection

The commonest garden hedging plant is green privet (Ligustrum ovalifolium), miles of which can be seen bordering suburban plots all over the country. Its main virtue is cheapness, but it has two serious disadvantages if used extensively: it is a very hungry plant, tending to impoverish the surrounding soil, and it needs frequent clipping. Another plant commonly used for short hedges is the small-leaved Japanese honeysuckle (Lonicera nitida). For tall screens the most frequently used are Lawson’s cypress (Chamaecyparis lawsoniana) and much-faster-growing Leyland cypress (Cupressocyparis x leylandii). All these ever-greens retain their colour throughout the year: although they provide an excellent background to flowers in summer, they make a rather monotonous contribution to garden colour in other seasons. Make a point, then, of choosing coloured-leaved cultivars to add variety to the scene. If you wish to use privet, for instance, the golden form (L. ovalifolium ‘Aureum’) will do much to brighten an otherwise cheerless, open site, especially in winter; be warned, however, that it may shed its leaves in severe winters if it is in an exposed position. The Japanese honeysuckle also has a beautiful golden form (L. nitida ‘Baggesen’s Gold’); it is, however, much more expensive that the golden privet and rather slow growing.

Some of the best hedging plants are provided by the conifers, including the various forms of Lawson’s cypress. The western red cedar (Thuja plicata) can be clipped to shape in August and makes a fine bright-green hedge, especially on chalk soils. It also has the advantage of being able to make new growth from old wood if it has to be cut back severely. Yew (Taxus baccata), in spite of its leisurely growth rate, can sometimes be encouraged to put on 150 mm (6 in) a year if it is kept well fed.

The common laurel (Primus laurocerasus) makes a fine hedge; its popularity, which waned after Victorian times, is now increasing as people rediscover its virtues. Few other evergreens grow as well in shade as the laurel, or put up so well with drips from overhanging trees. Its polished leaves are good reflectors, sparkling with yellow in sunlight, and echoing the blue of a clear sky on the shady side. One of its best cultivars for hedging is called ‘Rotundifolia’.

A rich colour can be provided by the related sand cherry (P. x cistena). It is deciduous, but its small crimson-purple leaves make a delightful show from spring to autumn; as a bonus it bears white flowers in March and April. Of modest growth-rate, in mature form it can be clipped to make a neat hedge of about 1.2 m (4 ft) or less.

Among several hollies, the best hedging ones are cultivars of Highclere holly (Ilex x altaclarensis), which are virtually thornless. One of the most decorative is ‘Lawsoniana’, whose dark green leaves are splashed with yellow. It bears orange-red berries throughout the winter. If possible choose an open site – the leaves lose their variegation if the hedge is permanently shaded.

imageCommon beech (Fagus sylvatica) is a superb hedging plant that, although not evergreen, holds on to its warm golden-brown leaves throughout the winter. Its young spring growth is pale green, turning to deep green in summer, so it provides changing interest through the year. An even greater variety can be had by planting a mixture of purple (copper) and green beech plants in one hedge. Beech is happy in most well-drained soils provided they are not too heavy. Where clay predominates it is better to plant the common hornbeam (Carpinus betidus), which also holds its leaves in winter, although they are smaller and duller in colour. Neither species should need clipping more than once a year in summer to keep it in good trim.

There are not a great many flowering shrubs that can be sheared into hedge-shape, but one that can is Berberis darwinii, an evergreen with small holly-like leaves and clusters of orange flowers in April and May that are followed in late summer by purple berries. It can make a dense hedge well over 2 m (6 ft) high, and its sole disadvantage is its prickles. Another good hedging barberry is B. x stenophylla. It forms a dense hedge from which arching branches emerge, bearing golden yellow flowers in April. It should be pruned immediately after flowering. A third barberry, B. gagnepainii lanceifolia, has an erect habit and forms a very narrow but dense hedge about 1.2 m (4 ft) in height. Its narrowness makes it ideal for screening off, say, a vegetable plot in a small garden. The spiny stems carry yellow flowers in spring and, later, blue-black berries. Although evergreen, the narrow leaves take on plum-red tints in the cold months.

The firethorns (Pyracantha), more commonly seen as evergreen wall shrubs, can also be trained as hedges. They carry white or cream, hawthorn-like flowers in clusters in June and July and brilliant berries in autumn.

Forsythias can also be used to make a flowering hedge, provided care is taken in the early years to get the base to fill out by means of pruning – or even by tying down some shoots if necessary. It is, of course, a more open shrub and deciduous, so the framework of stems is exposed during the winter. But there are enough examples around to show that it can be kept shapely. The best cultivar for the purpose is probably Forsythia x intermedia ‘Spectabilis’, with upright growth and an ability to withstand being clipped two or three times in the summer yet still flower well.

An uncommon but effective flowering hedge can be made from x Osmarea burkwoodii, a hardy, compact, slow-growing evergreen shrub that stands up to clipping and shaping. Its oval, dark-green, glossy, leathery leaves are 25-50 mm (1-2 in) long. Small, strongly scented white flowers develop in clusters at the ends and leaf joints of the previous year’s shoots in April and May. Once formed the hedge needs no more than an annual clipping in July. This allows time for the new shoots to develop and ripen before the cold weather arrives. Having an appearance rather like a hedge of box, it never looks untidy or overgrown if given this annual trim. Osmanthus delavayi, one of its parents, is another useful hedging plant that can be clipped to shape several times in a season. This, too has small, box-like foliage and bears white, scented flowers in April; but it is not fully hardy and is likely to do well only in mild areas of south-west England.

In the 1-1.2 m (3-4 ft) height level, the shrubby cinquefoil (Potentilla fruticosa) can be used to create a very effective summer-flowering hedge, blooming as it does from May to the autumn with single white or yellow flowers. It is not evergreen, but makes twiggy growth and can be clipped in winter.

Even shorter, at a mere 450 mm (18 in) or so, the silver-leaved cotton lavender (Santolina chamaecyparissus, syn. S. incana) can be trained to make a dwarf hedge in town gardens and in milder areas. It makes an effective border to a path and can have its uses in those open-plan front gardens where planting of tall bushes is banned. It bears lemon-yellow flowers in July.

Although much less formal in appearance, roses can make colourful flowering screens. The tall-growing, pink-flowered ‘Queen Elizabeth’ (a modern shrub rose sometimes grouped with the floribundas) is often used for this purpose, but the older stems can look rather gaunt; another suitable modern shrub variety is ‘Heidelberg’, with bright red flowers. Much better are the hybrid musk roses, such as the creamy-salmon ‘Penelope’ and the coppery-apricot ‘Cornelia’. Both are well scented, bloom throughout the summer, and make a hedge 1.2-1.5 m (4-5 ft) high, but you must allow at the very least 1m (3-1/4ft) of space for their width. The site must also be sunny if they are to flower well.

Japanese honeysuckle Lonicera nitida There are many other flowering shrubs that can be used to make informal hedges if you have sufficient room to allow them to develop. Unfortunately, however, space is so often at a premium in modern gardens. As a last resort you can contrive a screen from chestnut paling or chain-link fencing through which the shoots of ivy, honeysuckle, or some other climber are trained. Done with care so that the base is properly filled in, it can be remarkably attractive and certainly does not take up much lateral space, although of course the plants’ roots will project out into the soil on either side.

Always strongest at the top and so there is a tendency for a hedge to bulge out at the top between clippings. It is much better if the sides are clipped so that they slope inwards slightly towards the top, giving the hedge an ‘A’ shape when viewed end on. This ensures that the base gets a fair share of light and so remains green and healthy.

All too often established hedges receive no attention other than necessary clipping in summer. Many of them would be better if any rubbish were cleared away from their bases in the autumn and a scattering of bonemeal scratched into the soil around them. On poor and sandy soils a tired hedge often responds well to an annual, early spring dressing of general fertiliser and a 50 mm (2 in) layer of rotted manure, garden compost, or peat laced with bone meal, spread over a strip of soil at least 450 mm (18 in) wide over the root area on both sides. Apart from providing some plant food such a mulch helps conserve soil moisture during the dry summer months.

Maintenance

It is essential to curb your impatience for height and to trim plants such as privet, laurel, and Lonicera nitida regularly during their first full season of growth and thereafter. This is the only way to gain a sound foundation of shoots at the base. If they are allowed to rush straight up without this attention the bottom of the hedge will always be weak and gappy. It is also imperative to destroy weeds to prevent them from smothering the low growth, since this will seriously weaken it and may cause the basal shoots to die out.

The tendency for old hedges to become bare or gappy at the bottom may also be due to letting the top growth overhang the base. Although most people aim for straight, vertical sides when clipping a hedge, growth is always strongest at the top and so there is a tendency for a hedge to bulge out at the top between clippings. It is much better if the sides are clipped so that they slope inwards slightly towards the top, giving the hedge an ‘A’ shape when viewed end on. This ensures that the base gets a fair share of light and so remains green and healthy.

All too often established hedges receive no attention other than necessary clipping in summer. Many of them would be better if any rubbish were cleared away from their bases in the autumn and a scattering of bonemeal scratched into the soil around them. On poor and sandy soils a tired hedge often responds well to an annual, early spring dressing of general fertiliser and a 50 mm (2 in) layer of rotted manure, garden compost, or peat laced with bone meal, spread over a strip of soil at least 450 mm (18 in) wide over the root area on both sides. Apart from providing some plant food such a mulch helps conserve soil moisture during the dry summer months.

05. July 2013 by admin
Categories: Shrub and Tree Garden, Types of Gardens | Tags: , , | Comments Off on Guide to Garden Hedging

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