Globally, many complex issues, like the ageing population and health inequalities, require attention. People are experimenting to combat these issues in their local contexts through bigger or smaller networks; however, much of the knowledge about these initiatives remains localised and elitist and omits the voices and perspectives of citizens. This article identifies the characteristics of a more horizontal, emergent and plural epistemology to mobilize knowledge. We used local networks building age-friendly communities in the Netherlands as a case study. With members of 110 local networks, we worked with a new methodology called "dynamic knowledge synthesis" to create fruitful interactions and learn with stakeholders, including older citizens, in a learning community. Four working principles helped us, namely (1) a rhizomatic design based on multiplicity, heterogeneity and non-linearity of knowledge; (2) fertile soil nurtured by the talents and wisdom of participants through participatory arts-based methods; (3) so-called 'wicked skills' of a forester 2.0 to facilitate learning; and (4) an ecosystem metaphor as a boundary object to understand local networks. We invite colleagues to experiment with dynamic knowledge synthesis to connect on different levels, with particular attention to the inclusion of citizens in creating sustainable local communities.