Whilst objectivist epistemologies have been dominant in productivist agriculture, the local, cultural and environmental contexts of sustainable agriculture are more fully informed by constructivist epistemologies. Within constructivism, tacit knowledge – an intuitive knowledge that cannot be formalised – is explored empirically. Six types of tacit knowledge were identified as a result of working closely with a sustainable food network: the Brighton and Hove Food Partnership. Customs cohere around integrating food with other sustainable activity; developing a complex unregulated organisation requires savoir‐faire. The unique character of Brighton has developed an operational folklore, and network identity is important, particularly in relation to conventional agriculture and to the city as a whole. A confidence in people's roles has helped define network development and using different discourses, communicating the network in diverse contexts, is important for understanding the network. All these tacit knowledge elements have a strong influence over the network but have to be assimilated knowledge rather than learned.