In this paper, we explore legalising urban agriculture as a contested way of planning for decline, beyond the usual ‘mutual benefits’ narrative of urban agriculture in shrinking cities. Through the case study of Detroit (MI), we examine the content, implementation, and debates concerning zoning legislation legalising urban agriculture adopted in 2012 and assess both its advantages and drawbacks. This paper derives from fieldwork carried out in 2012–2013 and a qualitative method based on interviews with urban agriculture stakeholders, including several with the designer of the legislation as well as readings of the documents legalising urban agriculture. Our results show that legalising urban agriculture is not a beneficial practice per se, allowing a city to shrink ‘better’. We thus encourage advocates of legalising urban agriculture to encompass the complexity of decline as well as acknowledge the role of public policies in shaping a ‘just’ urban agriculture.