•Financing is an important barrier to developing public nature-based solutions.•The design, implementation and maintenance phases require different financing strategies.•The interplay between policy and financing is an important catalyst for investments.•Three approaches are identified to negotiate this interplay, and secure (public) resources. As climate change continues to impact cities, nature-based solutions (NBS) are being advanced as important adaptation strategies for mitigating these negative effects. As is the case throughout Europe, Flemish cities have enacted adaptation policies and plans outlining the importance of NBS. Nevertheless, the implementation of NBS has been slow. Local governments identify financing as an important barrier. Although private financing is often proposed as a solution, few studies have applied a public-financing perspective to generate insight into and remedies for such issues. In this article, we examine how four Flemish cities are financing NBS implemented in public spaces as climate adaptation strategies. Based on a multiple case study approach, our results uncover that different financing strategies are employed during the design, implementation and maintenance phase of developing NBS projects. Additionally, we learn that the interplay between policy and financing becomes an important catalyst for investments in public NBS. We identified three approaches administrations use to secure (public) resources. During the design phase, support is developed within the administration and politically through (1) fostering internal collaboration by developing integrated spatial NBS designs. In the implementation phase resources are attracted by (2) putting the developed spatial designs to work and seizing available funding opportunities. During the maintenance phase (3) strategic partnerships are established with NBS beneficiaries to alleviate costs for municipalities. We conclude that, in the absence of more long-term forms of public financing, these approaches offer smaller cities tools to overcome the financial barrier.