If you are ever lucky enough to take a helicopter flight over New York, you will undoubtedly be amazed by the dramatic rise of the skyscrapers mushrooming from the ground. You may be equally surprised to see how, in this futuristic land of cement and brick, green and leafy pockets of vegetation flourish on top of many of the buildings. This network of ‘sky gardens’ exists all over the Big Apple, creating a secret and enchanting world above unsuspecting passers-by in the streets below.
What I call ‘gardens on another level’ have now also become a common sight in other major cities, such as Tokyo, Berlin and Chicago, where the local powers-that-be have actively encouraged their creation. Sadly, despite Ken Livingston’s support for the concept – and the fact that many of the capital’s buildings easily have the capacity to support a roof garden – London is still rather lagging behind in this exciting development of the 21st century cityscape.
The economic, social and environmental advantages of having this additional green lung are many – and in many cases they benefit both the homeowner and the world at large. A sky garden will retain heat in the winter and cool a building in the summer, so saving on energy bills and helping to protect the fabric of the roof. It also gives the owner somewhere to grow fresh container vegetables and, above all, it will automatically add value to any property.
The social benefits of adding a top-level ‘extra room’ are obvious. It could be used as an entertainment space or as a relaxing, meditative area – the owner may even end up with a fantastic new vista! And finally, from an environmental point of view, the vegetation in a roof garden will absorb a significant amount of the surrounding pollution and produce more oxygen, so attracting birds and insects, absorbing rainfall and lowering local temperatures in the heat of the summer. These features are all particularly relevant in London’s heavily built-up areas. I recently finished a roof garden project at a flat in Brentford that was surrounded by a motorway, a railway line and a building site; many of the advantages I have mentioned will certainly apply to this property and its owners.
If you are interested in creating a roof garden, the first priority must be to get an engineer from a specialised firm to check that the structure of your home is able to support it. The design of the borders is also crucial; they must be secure and allow the wind to pass through them if they are to sit along both sides of the roof.
Of course, the plants you choose must be reasonably tough and capable of dealing with dry and windy conditions – remember, you are far more exposed to the elements, both good and bad, at a higher level. In my experience grasses, such as the Zebra Grass (Miscanthus var.sinensis Zebrinus) and other vegetation that thrives by the sea, work particularly well. Plants such as lavender are also particularly good at handling lofty conditions, and they also attract wildlife and provide a welcome splash of colour. Succulents that are accustomed to arid conditions, such as the Agave americana and any Sempervivum cultivars, also have a successful track record in roof gardens. In less exposed areas you could also plant bamboo, olive (Olea europea) and a number of small fruit trees – and don’t forget tomatoes, salads and herbs.
Roof gardens are fun, beautiful and intelligent spaces and in an increasingly congested city their potential is huge. So why not think green skies, as well as blue ones, this summer?
Sarah Bevin works for Urban Roof Gardens.
She can be contacted at sarah@urbanroofgardens.com