Windbreak Hedges and Shelter-Belts

Unless you happen to live in a farmhouse in the middle of a bleak fen, your attempts to alter the windspeed around your home will probably concentrate on the planting of a windbreak hedge rather than a true shelter-belt of trees. Before deciding on the type of hedging plant to use you will have to consider the local soil (clay, loam, peat, etc..); the degree of exposure of the site; the speed of growth of the hedge, and the final height required; whether the hedge is to be clipped or unclipped; the relative costs of the different plants; and finally, of course, your own personal preference. Whatever its relative merits, if you love the snowy blossom of the damson in springtime, then plant a damson hedge and enjoy it.

Windbreak hedges

If you are starting with a recently abandoned building site, where the earth is a typical mixture of sub-soil, brick bats and empty crisp packets, you must provide a bed of topsoil, with perhaps some well rotted manure or compost in which to start the young plants. In an established garden most hedging plants (e.g., hawthorn, blackthorn, holly and cherry plum) will accept a variety of soil conditions and grow well. If the soil is very acid the hardy purple rhododendron can be grown as a windbreak. For a chalky soil the common beech can be trained into a hedge; indeed, the beech can be so grown anywhere that is not wet. In wet soils the goat willow will grow rapidly into an untidy hedge, and the common alder would also be suitable.

The common alder, blackthorn and hawthorn all withstand strong winds, although hawthorn is not suitable for high altitudes, and will not grow under the shade of other trees. On very high ground and if the soil is thin and sandy, gorse will thrive and can be made to form an untidy hedge. The sea buckthorn makes a good windbreak hedge, will thrive in sandy areas and is useful for exposed coastal sites. Other hedging plants that will withstand salt laden winds include the maple, which is often seen in hedgerows in southern England, and elaeagnus. Not all hedging plants will thrive in shade but hornbeam will grow as long as the soil is not thin and holly will also tolerate a shady position.

In establishing something as long lasting as a windbreak hedge the rate at which the plants first grow may be an unimportant guide to the choice of species. However, for the impatient, hawthorn, willow and Leyland cypress will soon produce a hedge. The latter when grown as a tree will reach a height of fifteen metres and is characterised by a thin leading shoot which must be clipped to round about 300mm below the required final height in order to make the side shoots branch and thicken the top. At the other extreme, a hedge of common holly will grow very slowly.

For a formal clipped hedge, evergreens with small leaves, such as privet, cypress and holly, can all be trimmed to a precise shape. Beech can also be clipped as a formal hedge and, if trimmed in late summer, it will keep its russet leaves until the next spring. Plants with larger leaves are better kept as informal hedges and these need only minimal pruning with secateurs. Rhododendron, the outdoor fuschia, and cotoneaster (although the last two are actually small leaved) will all make useful informal windbreak hedges.

The rules for hedge planting are much more established than those for selecting a suitable species. Deciduous hedges should be planted in the autumn but evergreen are best left for the spring. For both types the ground where the hedge is to be established should be dug over deeply and all the roots of perennial weeds (such as bindweed and ground elder) should be removed. The prepared bed should be about 600mm wide and a layer of well rotted manure or compost should be put in about 300mm below the surface of the soil. With very wet ground, apart from choosing a water tolerant species of plant, it will help if a ridge about 300mm high is built up over the bed.

When buying the plants make sure that they are small enough not to need staking, say about 300mm high. It is also wise to sort the plants into similar sizes for planting as a large, strong plant placed next to a smaller specimen will grow faster and eventually suffocate the weaker plant, leaving gaps in the hedge.

Using a garden line as a guide, the specimens can be planted in a straight line or staggered, the exact spacing depending on the plant you have chosen (hawthorn 200-300mm apart; cypress 600-900mm apart); take advice on this when you are buying. Using the soil mark on the stem as a guide put the plants in to the same depth as they were in the nursery. Spread the roots when planting, cover them with fine earth and press the earth firmly round the stems with your heel.

The following spring and summer, if the weather is dry, you may need to water the plants: don’t just shower them briefly with a watering can, soak each plant with a whole can of water. Remember to keep young plants free of weeds. In very exposed sites it may be necessary to shelter them with a temporary fence or to support them by putting in stakes at either end of the row with string stretched between.

The general principles outlined will apply to all hedging plants, but when buying the plants it would be wise to enquire about the best way to set them out. The nursery should also be able to advise you about how and when to do the pruning to ensure a bushy hedge. As the idea is to encourage side branching at the expense of the growing tip, pruning will usually consist of cutting back all growths by half or a third of their length either at planting, leaving you with a very expensive handful of twigs, or in the first spring. An unclipped hedge should be left to grow up after this, although another severe pruning in the second year may help. Formal clipped hedges require more attention to achieve a better shape.

Shelter-belts

The difference between a windbreak hedge and a shelter-belt of trees is not clearly defined as the same plants can be used for both (e.g., common alder and Leyland cypress). However, trees in a true shelter-belt will be planted 1800- 2400mm apart, in two or three staggered rows. The types of trees to use are pines (the Austrian pine) which is useful on exposed sites; cypress (Lawson’s cypress, Leyland cypress); poplars (Lombardy poplar); alders (common alder); and, on wet soils, the white willow, the aim always being to grow a screen of trees as quickly as possible.

The trees should be planted very young so that the rapid root growth common to all young trees is made in the tree’s permanent position rather than in the nursery. This ensures that the tree is anchored firmly into the soil; it is especially important in the case of the cypress which should always be planted young and always in deep soil. The remarks about the preparation of the ground and the planting of the young specimens discussed for hedges also apply here although the spacings will be different. Again, the young plants should be well heeled in and looked after during the first year.

Before planting a windbreak hedge or a shelter-belt, you can probably get the best information on What specimens to choose by looking at what grows best in your area. In our own garden, on an area of heavy soil that is rather poorly drained, a line of willow fence posts that once supported the netting of a chicken run have now reached maturity as a fine screen of white willow 8 metres high.

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