Urban greening plays a crucial role in enhancing climate resilience, environmental quality, public health, and societal wellbeing. Policy makers at all levels are increasingly embracing greening and other nature-based solutions; however, successful implementation of these approaches requires a multidisciplinary strategy involving collaboration, community engagement, and adaptive interventions. This paper synthesizes key insights from an expert panel, comprising representatives of government agencies, research institutions, private sector, and local authorities, forming an international panel of experts, convened by the RECLAIM Network Plus (https://www.reclaim-network.org). Funded by the United Kingdom Research and Innovation (UKRI), this network project brings together over 650 members from 40 plus countries. It provides national leadership in urban greening, serving as a “one-stop-shop” for towns and cities to access green and blue infrastructure support, resources, and peer connections. The paper highlights grand challenges, priorities, successful case studies and opportunities in urban greening initiatives. The importance of strategic planning is also addressed, together with technological advancements and access to suitable data for maximizing the impact of green infrastructure as well as innovative funding models, such as corporate social responsibility and green finance. This work highlights the importance of an integrated, inclusive, and forward-thinking approach to urban greening for more resilient, sustainable, and equitable cities. Further, it emphasizes the need for cross-sector collaboration among local authorities, researchers, and businesses, as well as community involvement in successful planning for both short- and long-term outcomes. Ultimately, urban greening strategies must be informed by future climate scenarios while prioritizing equity and social justice to ensure adaptation options benefitting all communities.

Green and blue infrastructure (GBI) is emerging as a key strategy for climate adaptation and urban resilience, yet its implementation often faces critical contextual barriers. This review initially screened over 29,000 publications, ultimately synthesizing more than 500 relevant studies supplemented by diverse expert input. The result is a novel integrative framework that connects previously siloed knowledge and consolidates 21 underexplored barriers across four key domains of GBI implementation: environmental, social, economic, and governance/policy. Environmental barriers include conflicts between GBI and renewable energy goals, specifically photovoltaics, unintended consequences of GBI (such as allergenic pollen production), urban ventilation disruption, and vulnerability of plant species to multiple urban stressors. Effective responses include thoughtful allocation and integration of photovoltaics and GBI, developing context-specific frameworks combining ecological knowledge with technological innovation, fostering cross-disciplinary collaboration across technical and social domains, science-based species selection and implementing multi-scalar strategies that enhance ecological connectivity. Social barriers encompass environmental injustice, cultural disconnection, limited public adoption, safety concerns, and esthetic preferences favoring manicured over ecologically functional landscapes. These challenges highlight the need for participatory design, culturally responsive planning, and inclusive resource allocation to strengthen community engagement and long-term stewardship. Economic barriers stem from biodiversity undervaluation, inadequate asset recognition in accounting frameworks, incomplete cost-benefit analyses, and limited private investment. Innovative financing tools such as green bonds and debt-for-nature swaps offer promising mechanisms for resilient financing, while standardized natural capital accounting frameworks can better capture GBI’s multifunctional value. Governance barriers include land scarcity, urban design limitations, policy fragmentation, and disconnects with other urban agendas such as walkability. Overcoming these requires institutional realignment, cross-sectoral collaboration, and integrated spatial planning. The review unifies these findings into 12 actionable recommendations to support holistic decision-making, emphasizing that effective GBI implementation demands context-specific strategies combining innovation, inclusive governance, and long-term stewardship to mainstream GBI in sustainable urban development.