Over the last few decades, the concept of Green Infrastructures (GI) has been studied in several disciplines such as landscape architecture, landscape ecology and planning. However, scholars are still debating the best approaches to enhance the understanding of GI amongst practitioners. Indeed, a multi-disciplinary collaboration is needed to move beyond any obstacles to the development of GI. This paper presents a literature review that focuses on the barriers which still limit the adoption of GI, the concept of multifunctional GI, and the need for collaborative groups of professionals. In particular, the study explores the three Finnish cities of Vantaa, Tampere and Jyväskylä which are currently addressing new GI strategies and introducing the Urban Green Infrastructures within the built environment. The study presents the results from a multi-disciplinary collaborative process that consisted of a pre-questionnaire, learning activities, workshops, as well as a post-questionnaire. 23 official practitioners (architects, landscape architects, engineers and experts in natural sciences) from the city planning departments as well as four researchers in landscape architecture and urban planning were involved in the collaborative process. The results show that an understanding of GI gradually evolved amongst participants. The findings also reveal that rigid planning practices still represent obstacles to the development of GI. Hence, new urban planning approaches to the GI are needed, as well as more concrete actions involving stakeholders. New activities should be used when developing GI, such as learning about GI, proposing GI strategies and actions, as well as reflecting on existing planning tools.