How to Choose the Materials for Your Garden’s Horizontal Surfaces


It is absolutely essential for a designer to know at least something about the materials he or she intends to use. In the case of plants, even greater knowledge coupled with some experience is needed.

Apart from plants (with the exception of grass), the remaining materials can be broadly divided into two main groups: horizontal and vertical surfaces.

HORIZONTAL SURFACES

GRASS

It is important to realize that grass requires food, light and moisture just like any other plant. If it is to be used as a lawn it will have to withstand regular mowing, which means it will need to be an amenity type of grass, similar to those which are used for sports facilities. Its shape must also facilitate easy mowing. Tight corners, especially where these occur against retaining walls, tortuous curves and excessively steep slopes, all make mowing difficult. Where grass does come close to walls, steps and raised patios, a small gap can be left without grass. This is usually called a ‘mowing strip’ and might be constructed of some hard material such as brick, set flush with the lawn.

Garden’s Horizontal Surfaces

The best lawns are constructed on a good depth of even topsoil, at least 15 cm (6 in). Grass grows less well under trees and will die off quickly during droughts if old paths or areas of paving have been left beneath the surface.

Steep banks will need a hover-type mower or strimmer and if a ‘sit and ride’ mower is likely to be used, adequate width access must be given all round, especially to and from a mower shed.

Trees and shrubs

If these are growing in the lawn, mowing can be difficult, especially in small lawns. In larger gardens, areas of grass around trees could accommodate bulbs and wildflowers and be left unmown for much of the time. Sooner or later, perhaps towards the end of the growing season, this grass will need mowing. Distinction between this and regularly mown lawn can be defined on a plan by a dotted line. Having a definite mowing line does help to maintain a lawn shape in these areas and prevent the longer grass from looking like an example of blatant neglect!

Clover

Clover can be used as a ‘lawn’. It is not usually mown as closely as grass and may sometimes be left to flower (white). It, therefore, has a much less manicured appearance than grass but is relatively maintenance free and quite drought resistant. If, however, it becomes diseased, excessively untidy or riddled with weeds, it can be very difficult to remedy. I have seldom seen it equal the manicured appearance of grass but it can look quite neat from a distance. It is much better used under circumstances where a less formal effect is wanted.

Chamomile

This lush green creeping herb (Anthemis nobilis) is aromatic, releasing a pleasant fragrance when crushed underfoot. Because it bruises easily, it is not usually used on its own but grown with grass to form a slightly springy lawn. It should not be mown as closely as a normal lawn.

It is often best to have a chamomile lawn in only selected and limited areas of the garden, preferably somewhere not too hot and dry, perhaps in partial shade and certainly not where it will receive heavy wear and tear. It is difficult to control weeds in a chamomile lawn since, in effect, the chamomile is a weed and therefore precludes the use of selective weedkillers.

Automatic irrigation

This is essential in very dry districts if a lawn is to remain green and healthy at the height of summer. Although it can always be added later, it does help if a layout of pipes, nozzles and other facilities are positioned on paper at the design stage.

Edging

If it is important to preserve a very precise shape to a lawn as a part of the design, it is possible to install a timber, metal, brick or similar permanent edging. This is especially useful in light sandy soils which erode easily but is less critical in heavy clays. In areas of heavy foot traf­fic, along frequently used paths, under arches, main routes off the patio and so on, it is often best to have an area of hard paving rather than grass. This also applies to paths around vegetable and fruit gardens where soil may be spilled and heavy wheelbarrows are used, and to the areas immediately around and alongside washing lines, particularly during wet winters when the grass cannot easily recover.

BARK AND FIBRE

There are a number of products, derived from trees, which can be spread over the ground to produce a useful and often attractive surface. The bark from a number of different trees is available in various grades, most usefully as ‘chips’. These are usually spread either over planted borders as a mulch against weeds or onto compacted ground as a path. The mulch would need to be about 100 mm (4 in) thick but a path covering would be less. All these products are brown and have a texture which goes well in wood­land settings or wild gardens. Paths would need some form of edging to contain the material. I once saw these chips used near a house in a very modern scheme which displayed a number of contrasting materials. Unfortunately, once the chips have become wet they often release a brown stain and this was trodden into the house carpets! It is important to remember these chips are very unstable and can be kicked or scuffed out of place. They are not really suitable for wheeled traffic nor for heavy pedestrian traffic unless they are on an exceptionally well drained, firm base.

SHINGLE

Most shingle is derived from river bed deposits. As such it is usually made up of rounded stones which never compact very well. This means that they are always mobile and crunch under foot. If laid to any great depth they are difficult to walk on so, as a general rule, they should not be more than say 3 stones deep. Most shingles are used as a covering or dres­sing over some more substantial base and therefore their suitability for various practical situations depends almost entirely on what is put underneath. A common base for shingle paths or drive­ways is compacted hoggin. Shingle is often graded into pebbles of a certain size, 5 mm, 10 mm, 20 mm etc. Colour is very variable but is mostly brown, yellow or creamy white.

GRAVEL

Gravels tend to have more angular stones, very often as a result of crushing rock. Those which have been washed and graded tend to behave rather like shingle, being reluctant to compact. Other gravels are made up from several stone sizes together with some dust and these do compact to produce a reasonably stable surface. This could be used to a thickness of about 25 mm (1 in) although its use will still depend partly on the type of base. Gravels are available in a wide range of colours and can be used purely for decorative purposes, even as a coloured mulch around certain plants.

SCALPINGS

This is a mixture of relatively large and small pieces of crushed rock mixed with dust. When compacted it can produce a very hard surface, but is not particularly attractive. The larger stones may kick out and it is really only used as a base for patios, paths, driveways and even motor­ways. Just occasionally it is used for tracks running through woodland or forestry developments. Its compacted thickness beneath a driveway could be 150 mm (6 in) more for a road, less for a path.

PATH GRAVELS

These seem to be a cross between gravel and scalpings. They have the ability to compact like scalpings yet have an attrac­tive gritty or dusty surface. There are many colours and textures available depending upon which pit they have come from. Some are rusty brown, others grey and all produce a very attractive and reasonably stable path or driveway surface. They do, however, need a firm base, perhaps of scalpings, and are not usually laid deeper than about 35 mm compacted.

All shingles and gravels have to be contained by edgings or kerbs. These might be brick, timber, concrete, natural stone etc. Where shingle (or gravel) comes against a lawn, it is wise to have the shingle at least 25 mm (1 in) below the lawn but with the kerbs higher, at lawn level. This helps to prevent the shingle from migrating into surrounding areas. The same applies to the edges of plant borders.

On steeply sloping driveways and paths, path gravel is likely to be more stable than shingle but constant heavy rain can cause serious erosion to both. Flat, poorly drained areas may cause path gravel to become mossy or even soft, with the added danger of freezing in winter. On thawing, path gravels tend to become very sticky. A well drained base or good surface drainage is important.

Garden’s Horizontal Surfaces

HOGGIN

This is a mixture of roundish stones (various sizes), sand and clay. When compacted it becomes rock hard. Mixtures containing the largest stones are only useful for rough tracks or as a base beneath other forms of paving. The finer grades, with smaller stones can make attractive paths and driveways but these must have some form of kerb or edging and be well drained. Hoggin is usually a sandy colour or brown and its surface can be enhanced by a thin layer of shingle.

TIMBER

Planks of timber are often used for patios, decking and walkways. Hardwoods are best because they have a high resistance to decay and because they are less likely to splinter than softwood. Softwood decays much more readily but if it has been pressure treated, it will resist decay for many years. Hardwoods are not usually stained but merely enhanced with a suitable ‘paint-on’ product. Softwood, on the other hand, takes stain very well and can be given a wide range of colours. Horizontal timber surfaces do not perform very well in wet areas, or where there is constant shade. A common problem is that they become slippery with algae, although it is possible to clean this off. An exception could be made in a woodland setting where timber can look especially attractive and where, perhaps, its disadvantages can be tolerated. Under these circumstances, any softwood should have a ‘sawn’ finish (rough surface) as opposed to being planed or ‘prepared’ (smooth).

Clay bricks

Brick paving and edging is widely used in gardens, especially if there is already some brick in various buildings nearby. The bricks must be hard and frost resis­tant — described as ‘stock’ bricks or possibly engineering bricks, although the latter are often very smooth and could become slippery. Bricks can be used in all manner of ways but it is important to remember that water may drain rather slowly from their surface and that to avoid the possibility of a slippery surface they must have a good slope (fall) towards a suitable soakaway.

Bricks can be used to create a number of interesting patterns, but do not rely on their dimensions being as exact as these illustrations portray.

BRICK PAVIORS

These are made specifically for paving. Unlike house bricks, they are usually thinner and are made to fit together, often without the need for pointing. Their surface is often more precise than a stock brick, and their overall appearance more modern. Brick paviors are also available in interesting shapes which can be used to create interlocking patterns.

CONCRETE PAVIORS

These are available in a similar range of shapes and sizes to clay bricks and paviors. Their surface seldom looks as mellow as that of clay units but they are available in a wide range of colours and shapes which, again, make it possible to create interesting patterns. Especially valuable are those which are shaped in such a way as to make tight circles possible. Circles in bricks are more difficult to achieve, especially near the centre, and even with the bricks used on end (probably as half bricks) joints can become irritatingly wide.

CERAMIC TILES

These are used to surface a solid and stable base and provide a useful dimen­sion in patio design. Although commonly associated with the surround to swim­ming pools and the floors in conser­vatories, there is no reason why they should not be used in other paving projects, so long as they are suitable for outdoor use, frost resistant and unlikely to become slippery.

NATURAL STONE PAVING

Pieces of natural stone have always been used for garden paving. There are natur­ally many different types, some being more suitable than others. At one end of the range, pieces of marble and slate will produce a hard, smooth elegant surface but this may become slippery when wet. In contrast, some of the softest sandstones (usually brown in colour) are of little use since they soak up water and disintegrate after frost. Some stone is available as random-sized rectangular pieces and these are used to create a ‘random rectangular’ pattern. Other stone comes as ‘broken’ stone, pieces of all shapes and sizes, and this is used to create areas of crazy paving. A brick edging can often enhance these areas and link them with the surrounding buildings.

GRANITE SETTS AND COBBLES

These are often known as one and the same thing. Square or rectan­gular blocks of stone, usually granite, are often used to pave the surface of drive­ways and roads. Some are quite small and useful for circular patterns. They are also used as kerbs to driveways and roads but are just a little too chunky or clumsy for the edge of narrow paths. The most common colour is dark grey. Also known as cobbles are the large round or oval pebbles which are often found on beaches or in chalky areas. They can either be mortared together to produce an attractive surface (which is difficult to walk on) or they can be laid loose in or around water features. They are also useful in a Japanese-style garden along with large boulders and stones of other sizes. Their colour is usually grey or light brown.

CONCRETE SLABS

Because of the relatively high cost of natural materials, a huge range of concrete slabs is available, some imitating natural stone, others displaying a more modern face. Those with a rustic stone­like surface are called ‘riven’. Others have a smooth but non-slip surface, and many are available in several sizes which, together, make a pattern. Some of the more expensive slabs use a high propor­tion of natural, crushed stone and are described as ‘reconstituted stone’ slabs. The designer has almost infinite choice, especially if natural and manufactured products are intermixed.

Garden’s Horizontal Surfaces

It is important to appreciate that slabs vary in strength. Those which have been hydraulically pressed during manufac­ture are the strongest and usually have the flattest surface (which is sometimes polished.) Some slabs are vibrated and these tend to be rather brittle although they do often have a non-slip surface. A good number of the more decorative slabs, particularly those with a riven or patterned surface are made in a mould. They may vary a little in thickness and are not very strong.

TARMACADAM

This is obviously used mainly for roads and driveways and seldom in the garden. In some surroundings, the red/brown form can look more attractive than the black. It should always be used with a kerb or edging and be given good surface drainage. It is usually laid over scalpings or hoggin and its surface can be tar sprayed for a thin dressing of shingle or chippings. This does at least give the appearance of a shingle driveway or path without the disadvantages, but the shingle may wear off after a year or so and need renovating.

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About the Author: Greenery always attracts Arthur Kunkle. He has a big garden where he plants many fruits and vegetables. His passion for gardening motivates him to write and share different tips on gardening.

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