In recent years, the global decline in biodiversity due to worsening environmental conditions, such as climate change, has become a major concern. The urgency for conservation measures to protect biodiversity, especially indigenous plant species, has never been greater. Arboretums and urban gardens are playing a crucial role in preserving plant diversity and are increasingly acknowledged as important for urban biodiversity and as carbon sinks. As we mark the International Day for Biodiversity on May 22, it is important to acknowledge the vital role of arboretums and gardens in biodiversity conservation and enhancement. Arboretums serve as havens for a wide range of plant species, contributing to the preservation of genetic resources and playing a key role in research, education, and public engagement. Meanwhile, urban gardens are becoming important contributors to urban biodiversity conservation, providing habitats for wildlife, supporting pollinators, and acting as carbon sinks. These gardens also offer valuable opportunities for community engagement, environmental education, and sustainable practices, empowering individuals and communities to actively participate in biodiversity conservation efforts. The Korea Forest Service has announced plans to strengthen the collection and conservation of rare, endemic, and endangered plants, as well as to enhance the conservation and restoration of biodiversity, promoting garden culture and boosting the garden industry. On this International Day for Biodiversity, it is crucial to recognize the significant role of arboretums and gardens in biodiversity conservation and enhancement. Collaborative efforts between arboretums, gardens, policymakers, and communities are essential to effectively address the challenges facing biodiversity and work towards a sustainable future for all life on Earth.