Flat Rooftop Gardens and Balcony Gardening
Balconies and flat rooftop gardens can be made very bright and colourful with a little forethought and planning of their design and content. Containers really come into their own in these situations.
Garden Tubs and Containers – Weight Problem
It really isn’t a good idea to put unnecessary weight on flat rooftop gardens and balconies, so lightweight containers are always to be recommended, such as fibreglass or plastic tubs and troughs etc. There is a wide choice of these available.
To keep your rooftoplight, fill them with lightweight potting compost or , such as an all-peat variety. Gro-bags are very useful for growing your plants on balconies and rooftop gardens, and there is no reason why you can’t grow colourful bedding plants in addition to vegetables in them. Cascading and trailing plants will completely cover and hide the gro-bags which are actually acting primarily as utility containers.
Provided the rooftop or balcony is strong enough, you could possibly even consider having a small garden-pool in a tub. However, you must be particularly cautious with flat rooftop gardens. Some of them will not take much weight at all and are not designed to be used as outdoor gardens or living areas. This definitely applies to flat roofs of house extensions which have simply been boarded and covered with roofing felt. You would be surprised that even lightweight containers filled with a peat only soil can be amazingly heavy straight after watering and a group of a dozen or so could just be too much weight for some roofs. It may be a good idea to place containers around the edges of rooftop gardens, as this is the area of greatest strength – rather than making a collection of them in the middle, which is the weakest area.
It is also recommended to slightly raise the gardening containers off the rooftop floor using blocks of wood. This will allow for freeof any surplus water and will ensure good circulation of air beneath. This will benefit not only the plants but the roof also.
It is advisable to consult with either an architect or a structural engineer in order to determine to what extent a rooftop can be used for outdoor living and growing plants. You should also consult the local planning authority so that you can find out whether it is legal to have a garden on a rooftop in your area and to discover if there are any particular safety measures you should be undertaking.
Other Types of Containers
Some containers, like hanging flower baskets and fixed wall planters, of course, do not contribute to any substantial weight; they are great for both balcony gardening and roof gardening also. If there are any external windowsills, thencan be filled and used to add yet more colour. If a balcony has a sturdy wall around the edge, it could be possible to mount window flower boxes on top. Each planter should have a drip tray beneath it, and even more importantly the planters should be very securely fixed to the wall by means of appropriate fixings and brackets.
Wind and Sunshine
Being high up, balconies and rooftop gardens, are often a little more prone to the effects of colder winds than ground level gardens. The wind can whip around the plants, swaying them dramatically and therefore cause damage to them. Drying winds can quickly dry out any soil or compost and give cause windburn to their foliage. Plants can also just have too much sun – extremely hot sun can not only damage the plants themselves, but it can also dry the soil out very quickly.
If you know that either wind or sun is going to be a problem for your rooftop garden or balcony, then it would be wise to try to choose plants that will tolerate them. Or at least provide some sort of protection against the elements.
Rather than trying to block out the wind entirely with solid panels that could look awkward or lead to turbulence as the wind travels over and around them, you could filter or slow the wind down with the use of trellis panelling. Ready-made wooden trellis panels are available up to 1.8m (6ft) in height. Be aware though, that when fixing them to the boundary walls or indeed anywhere on the rooftop, that they should be very secure. Balcony gardens can really only be partially screened, of course; perhaps trellis panels at each end would work well.
Trellis panels also make perfect supports for, and these plants would in turn add extra wind protection to the panels. I would suggest that you choose really tough for the screens and that you grow them in tubs of a suitable size. Ivies instantly come to mind, particularly cultivars of Hedera helix, which is the toughest climbing species. Climbing of modest stature are comparatively tough and so is the winter-flowering jasmine, Jasminum nudiflorum, whose yellow give a lift to dark gloomy days. The climbing hydrangea, Hydrangea petiolaris, is an amenable plant, as it tolerates both shade and atmospheric pollution, whilst producing large heads of greenish-white flowers in early summer.