"Greenhousing": Integrating low-input simplified hydroponics for roof gardening in bologna's public housing

Since 2007, most people of the world live in cities. Urban agriculture, and more specifically urban horticulture may allow improvements in food supply and reduce the city ecological footprint. Furthermore, gardening practices are associated with social and therapeutic effects. In the last decades, as a consequence of the increased awareness on its related benefits, urban horticulture has assumed a paramount role in defining the city landscape. It is true, however, that within cities, the main constraint to the expansion of agriculture is represented by land availability and soil fertility. Simplified soilless gardens are getting more popular worldwide since they allow cultivation in courtyards, small gardens, walls, balconies, and rooftops, also by intensifying production per surface area, since plants are provided with nutrient and water according to their needs. Moreover, simplified soilless systems may use low-cost recycled materials to build growing containers, and through the adoption of closed cycles water-and nutrientsefficiency is improved. Starting from 2011, the Greenhousing project aims at the introduction of soilless gardens in the rooftop of public housing buildings of the city of Bologna, Italy. In the present paper the beneficial elements of multifunctionality of these gardens will be outlined.