A significant number of public gardens own or manage natural areas or are directly involved in in-situ conservation within protected natural spaces. Sometimes single natural areas just aren’t enough to ensure the protection of species and habitats. Reinforcing ecological connections and corridors can be advanced by forming alliances among organizations that themselves own or manage natural areas in proximity. We showcase five examples of major public gardens in leadership roles in land conservation alliances, with strong emphasis on plant species diversity and plant conservation. Each of these programs involves different types of partner agencies and conservation programs, but all enhance and extend the plant conservation work of their leading public garden to new locations, conservation challenges, and audiences.