Gardening Ideas: Rooftop Gardening

Many older buildings — and quite a lot of modern, tall flats — lend themselves to rooftop gardening. If you are planning a roof garden, it is wise to get some expert advice — just to make sure that the roof is structurally sound and will be able to stand not only the weight of the garden, but also the regular tread of human feet. Once that is established you can begin your planning.

The size, lavishness and luxury of your roof garden will depend on your pocket. If, for instance, you are able to call in specialist assistance for structural additions, perhaps designed by an architect, your garden in the clouds can be quite spectacular. There will be scope for a wide range of features, like archways, sheltered areas, water features, an aviary, special lighting, furniture and even a miniature greenhouse, all of which can be built in lightweight materials if necessary.

The first thing to remember is the garden will be entirely artificial and that all your materials will probably have to be carried up several flights of stairs — unless you have a lift or are able to get hold of a builder’s pulley. So bear this in mind as you begin your planning. And while mentioning planning, you will be advised — as with all garden design situations — to work to a scale drawing.

Rockefeller Center rooftop 2 gardens

Image via Wikipedia

The design itself will have little resemblance to ground level planning. There will be few landscape features to take into account, apart from other buildings and passing clouds. There will be no need to establish privacy, though you will require screens for shade, not only for yourself but also for the plant life. The rooftop scene will be scorching in the heat of summer and your soil beds will not have the natural power of conserving moisture.

The rooftop can also be fairly desolate, so you will need to establish shields around the edge of the roof to screen your garden from a somewhat bleak outlook and also to form a resistance to the wind which will also be more noticeable.

Take a note of existing structures, such as a protruding chimney breast or lift housing that may be utilised for your own construction work and for the siting of secluded alcoves. It is important at an early stage to examine the roof surround. Most flat roofs will have a wall of reasonable height, but for safety’s sake this may require additional building to make it at least four feet high.

The walls themselves can be used as an extension of your gardening space, by clothing them with climbers and hanging baskets. It is likely they will be of bare brick — so before you put in the plants, paint it all with cement-based paint, available in many pastel colours. This will have the effect of illuminating the green foliage that will be growing against it. A white wall will also highlight the various container-grown trees and shrubs close to the wall for additional windbreaks. This sort of perimeter arrangement of climber and container specimens will also help add a degree of depth to the garden. Banking schemes can also be used against walls. Taller conifers, for example, can be grouped as a backcloth to a row of more prostrate shrubs.

The beds should be long and narrow, and with imaginative planting some really excellent features can be worked out. Island beds can be used well, but these generally need a fairly open area to set them off. Try also to establish some focal point that attracts the eye as you enter the garden; a specimen tree or shrub, or perhaps a pergola clothed with climbers around a protruding structure. So to sum up, the basic design will follow these lines: a central focal point, a logical, rather formal arrangement of beds whose low line will be interrupted by occasional prostrate trees or shrubs; a backdrop or shield of climbers and taller specimen subjects. Additional windscreens and shade can be effected by building a fairly sturdy trellis on the wall or parapet surrounding the garden.

Beds will naturally be contained in wooden structures, light concrete blocks or peat blocks, and you will be advised to place a layer of heavy gauge polythene beneath each bed. They will require regular water throughout the year so some sort of rainwater conservation arrangement on the roof will be handy, otherwise you will be forever carting up buckets of water.

In fact, if space allows, a screened section for your tools, compost heaps and peat reserves will also be useful. Soil may be in short supply, so supplies of peat, humus and soft sand should be available on the roof.

The floor of your roof can be ‘paved’ for a patio area or a path. There are now on the market some lightweight concrete-based patio tiles which would be suitable.

Large areas of water are usually out of the question because of the weight factor, but you might consider a small water garden with either a polythene or fibre-glass pool.

Although you will have plenty of year-round heat on the roof — scorching in summer from above and comfortable from heat rising from the building in winter — you may wish to install a greenhouse for additional interest. Again there are several all-polythene, lightweight models available that are ideal for this situation — but they must be properly anchored to the roof or they will blow away during high winds.

Grass can be grown on the roof with varying degrees of success, but remember that you will require at least six inches of soil and a good supply of water and constant maintenance.

There are simulated lawn carpets, rather expensive, admittedly, but entirely trouble free and eminently suitable for the roof.

05. September 2011 by admin
Categories: Gardening Ideas, Roof Gardens | Tags: , , , | Comments Off on Gardening Ideas: Rooftop Gardening


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