Rooftop gardening is not a new idea: people from ancient Babylon, from the Roman city of Caesarea and many other places took advantage of their roof spaces to grow all kind of plants. This practice is gaining new popularity today, as cities grow and access to land for gardening is limited.
Turning roofs green can add some appeal to urban spaces dominated by concrete and asphalt, offering attractive views while providing an ecological isolation layer for the building and capturing some of the city’s carbon emissions. Architects and urban planners from all corners of the world have perfectly grasped the great potential of rooftop gardens and have incorporated them in public buildings design or in city center renewal projects. The roof of Chicago’s City Hall is now covered by a flowering garden and a large tree park forms a canopy over the Fukuoka Prefectural International Hall in Japan. City farms have propagated in many metropolises such as New York, Toronto, set up on long roofs atop busy streets.
Less spectacular although more crucial are the small scale, individual or community rooftop vegetable gardens that supply fresh green products to families suffering from food insecurity. In Bethlehem’s crowded Dheisheh refugee camp, fifteen families now benefit from rooftop micro farms that have been set up by the women’s group Karama. The simple garden system, made of open pipes placed of the roofs and filled with soil, is covered by a large net providing some shade to the plants, lowering the need for water. In Gaza also some inhabitants are planting herbs and seasonal plants on their rooftops to supplement the family diet. In July 2010 the Food and Agriculture Organization (FAO) launched an emergency food project, providing several hundred households with innovative rooftop garden units, combining a vertical garden connected to a fish tank.
Got a flat roof and want to create your own rooftop garden, to enjoy some greenery and your own vegetables? You got the spirit! Check first the legality of your project: you may have to obtain adequate authorization, especially if you live in a block of flats. In addition, ensure that you have an adequate, safe access to your future garden. Then, first step before getting your hands muddy is to assess the weight bearing capacity of your roof. Few buildings could bear a forest, and as you are planning to bring soil for your future garden bed, think carefully about how heavy it is: a fifty centimeters deep soil covering the entire roof is more than most buildings’ capacity. Still, you will have the options of using lighter soil and lightweight containers adapted to your needs and your space.
Your next concern might be the exposure of your garden to wind, sun and heat. Carefully choose your plants to resist to these harsh conditions, using drought-resistant local varieties, and provide them with shade and a windbreak if needed. You may want to use some resistant plants themselves as a windbreak to protect the more delicate ones. Also make sure your watering system is adequate. Plants on a roof are likely to experience more evapotranspiration and shallow soil retains less humidity, thus watering needs to get some special attention. In order to save water, you could install a rooftop water collection system. Last but not least, to feed your plants, think of making your own compost. Compost can be produced with very little effort, in a backyard or indoors, using most of the organic waste from your kitchen and from the yard; once the matter is well-broken up or “composted”, it will provide your rooftop garden with a natural fertilizer.
Then… well, let it grow and enjoy! And if you live in a collective building, why not organize with your neighbors to create a shared rooftop garden that everyone can enjoy?
This blog post has been written by FoEME intern Amélie Joseph. Amélie holds a MA in agronomy and environment and is working with FoEME on water-related issues in agriculture, in Tel Aviv office.