There are many advocates and critics of urban agriculture’s role in a sustainable food system but little quantitative data, potentially due the difficulties in collecting it. Urban food production is an example of a distributed system intrinsically linked to urban farmers and urban lifestyles and therefore cannot be recreated in a lab. Citizen science (CS) is identified as a potential method to measure aspects of urban agriculture but has potential issues associated with maintaining participation in data collection. This paper presents the development of a citizen science methodology combining general CS project design methods with methods for engaging and retaining participants in CS projects, based on motivation, for the design of a citizen science project measuring the sustainability performance of urban food gardens in Melbourne, Australia. It was found that an additional motivation emerged that is not yet documented in existing literature and is particular to citizen science projects. Other conclusions were also drawn related to timeline management, potential cost reductions conflicting with reducing barriers to participation and diversifying recruitment methods to attract participants with more time to be involved.