What does the urban gardener do, in the process of reclaiming and transforming previously vacant and abandoned land? What are the political, social, and ecological implications of creating community managed and owned spaces through urban agriculture? To address such questions, in the context of work that is being done across the world to transform vacant land into community resources, this article investigates the powerful potential of community managed gardening projects from the perspective of urban citizenship. First, the term “urban citizenship” is explored, with particular emphasis on the distinction between passive and active forms of citizenship. The article then explores the kind of city that gardening practices produce when they aspire toward their radical potential as manifestations of urban citizenship, with cases from Boston, New York, and Philadelphia that unearth empowering and effective fields of action. Insights from theory and practice reveal how community managed gardening projects can create opportunities for creative political participation, the development of local leadership, and ultimately a resilient social infrastructure that top down policy or business models are unlikely to achieve. Finally, the article suggests that organizing gardening and sustainability initiatives as a project of urban citizenship could fundamentally remake urban society—in a way that is more equitable and responsive to local contexts—as it generates community capacity in the age of 21st century urbanization.