Nature-based solutions (NBS) can act as a valuable complement to conventional ‘grey’ infrastructure for stormwater management (e.g. dams and dikes) in reducing flood risks as these ‘green’ solutions are perceived to be more flexible and multifunctional. However, to achieve effective NBS, a multi-actor approach in developing appropriate measures for specific sites is required as NBS occupy more space than ‘grey’ infrastructure and often overlap with private land. NBS also necessitate a multidisciplinary approach, to maximise environmental, social, and economic benefits. Thus, a transdisciplinary approach is needed for the effective implementation of NBS. Viewing NBS as a boundary concept, focusing on the common ground for different disciplines and actors, can facilitate communication and provide a first step towards effective flood risk mitigation.