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The FEW-meter project was developed by an international consortium comprising researchers, practitioners, and associations in the urban agriculture sector from five countries: France, Germany, Poland, the UK, and the US. The project was funded under the Sustainable Urbanization Global Initiative (SUGI), Food-Water- Energy Nexus call, established by a Joint Programming Initiative of the Belmont Forum and Urban Europe. The consortium´s submission proposed to investigate the FEW-nexus in urban agriculture. At the core of our project is the collaboration between researchers, farmers and gardeners. We invited associations to cooperate, such as the Polish Allotment Gardeners Association, the German Landesverband Westfalen und Lippe der Kleingärtner, which represent allotments holders in the regions of these countries where some case studies are located, Jardin des Eglantiers - a local French allotment garden association, Social Farms & Gardens (the UK charity representing community gardens and city farms), and Green City Force (a US-based organization training young people from low-income social housing communities to farm). Their insights, experience and dedication were invaluable and enabled the co-production of new knowledge. They supported the recruitment of case studies, participated in workshops and, together with farmers and gardeners from our case studies, provided constructive feedback for the development of the project’s methodology and data analysis. This report presents the main outcomes of the three-year FEW-meter project.&nbsp

International audience; Rooftop gardens are a promising way to supplement the growing demand for local food production, and are especially relevant in large cities with acute space constraints. However, they face the challenge of achieving viable food productivity while minimizing their impacts on the environment, two priorities that often oppose one another. Also, the actual impacts of management practices, which are deemed environmentally friendly in principle, are rarely quantified. Therefore, evaluations that encompass all components of urban gardens and a comprehensive range of environmental issues are necessary to reveal potential trade-offs and provide guidance in the design of these systems. In this study, we evaluated the environmental and economic impacts of rooftop gardening practices, focusing on crop and substrate selection, which are key parameters in system design but whose consequences have seldom been evaluated so far. Life cycle assessment (LCA) and life cycle costing (LCC) were used to analyze a case study in the center of Paris (France). The production systems considered involved crop rotations of tomato and lettuce each grown in three different substrate types: compost and wood chips; compost, wood chips, and earthworms; and conventional potting soil. Despite the large environmental burdens of compost production, systems with compost performed better environmentally and economically than the system involving potting soil, specifically having 17-47% less greenhouse gas emissions per kg of product. Across systems, length of cultivation and yield appeared to be the most influential determinants of the environmental impacts. Within the compost systems, the most impactful component was the material used for garden infrastructure, and substrate production for the potting soil systems. This is the first study that considers compost as a substrate, weighs its benefits and impacts, incorporates it into a complete garden, and compares it to potting soil. Our results demonstrate that careful system design could significantly abate environmental impacts. They provide critically needed information to people implementing urban rooftop agriculture and considering the trade-offs involved in each decision.; Rooftop garden