BRILLIANT TIPS OF ROOF GARDENS

If a roof has been specially constructed to take a conventional garden, it can bear enough soil for a lawn and plants to grow in. However, such roofs are extremely rare. Most are not meant to be used for anything, so if your plans are at all ambitious, it's vital to get advice from a building surveyour or architect. Otherwise, it's largely a matter of common sense. Keep as much weight off the roof as possible, by using wall-hung pots, baskets and troughs. If there are no walls, although you may need planning consent before going ahead, You could build them up from the walls of the house. Alternatively, you could create an evergreen hedge in pots or troughs-making sure to position them over the walls of the house, so they take the weight instead of the roof. Alos make sure they are very firmly fixed: rooftops are very windy places, and even a small flower pot falling from a height could kill anyone in the street below. Choose lightweight containers for floor-standing plants-plastic or fibreglass rather than stone or cast iron. And even though they are light, keep them on the small side, because they will become very heavy once they are filled with soil, and even heavier when the soil is watered. (Indeed, it might be better to fill the containers with peat compost, because this is much lighter than ordinary earth.) I dually, keep the pots near the edges too, because this is where the roof is at its strongest.

Most roofs are covered with a bituminous compound or lead sheeting, both comparatively soft materials, particularly in hot weather. This means they could easily get cut by heavy or sharp containers, which would cause leakage through to the ceiling below. It makes sense, therefore, to spread the load as widely as possible, either by using shallow containers, or resting containers on planks of wood. If you are sure your roof can take the additional weight, you could have it covered with special lightweight outdoor tiles; although asbestos-cement tiles are still manufactured, non-asbestos equivalents are now available.

The snag about creating a lightweight roof garden is that container-grown plants dry out very quickly; peat dries out more rapidly than soil; shallow containers dry out faster than deep ones; and roofs are very exposed to wind, which has a harsher drying effect even than strong sunlight. This means plants may need daily water in summer as well as fairly frequent watering in winter and, as in window boxes, they are going to need feeding. Furthermore, plants that thrive quite happily at ground level may so dislike the wind and polluted atmosphere that they die on a rooftop. Given that plants will need extra attention to survive, and that everything needed for them- from peat and containers to tools and possibly water- will need lugging up a flight of stairs, there seems little point to creating a roof garden if you have got one below. Even if you don't have any other form of garden, it's vital to be sensible about what you attempt. The average roof is only intended to take the weight of snow, and an occasional repair-man. If in addition to the weight of pot plants, you add a table and chairs and start inviting friends round for al fresco meals, you are just asking for serious structural problems.

If this is what you want to use a roof garden for, you will need to have an entirely new roof constructed. If, on the other hand, all you want is to potter peacefully on a private island' walled' with plants and flowers, and have somewhere to sunbathe with a (preferably lightweight) friend, the charm of a roof garden in the middle of a town is such that you won't be put off by the snags. As with all container- grown gardens, you will be able to enjoy one major advantage. You can grow acid lovers and acid haters in pots next to each other: think of azaleas beside pinks, or camellias beside peonies. Another plus factor: you shouldn't have to do much weeding, because you are too hogh up for most wind-blown seeds, and will only have to bother with those the birds deposit.

FURNISHING THE OUTSIDE

The ideal garden furniture looks good, is comfortable, and can be left out all year round but unfortunately it doesn't exist.