RESUMEN
Despite growing interest in promoting urban biodiversity conservation, there are few concrete examples of how nature stewardship initiatives can be rapidly scaled, in number and across landscapes. This paper explores the factors that promote or inhibit the proliferation and impact of collaborations between citizens and their local governments that involve residents in municipal biodiversity conservation efforts in their gardens (wildlife gardening). We studied the Gardens for Wildlife Victoria network in Australia, which supports citizen-agency co-development of municipal wildlife gardening programs. In three years the network has expanded from one program to 39 initiatives in various developmental stages in 49% of the local government areas in the state of Victoria. Data are drawn from 21 semi-structured interviews of network participants running or developing programs in 12 municipalities, complemented by a survey of 33 network participants, and participants' evaluation of network workshops. We find that scaling occurs in four different domains of policy, values, locales and participants. Scaling is influenced by six interlinked factors: empowerment of actors; a civil-agency co-design and delivery model; conservation framing; links to and between landscapes and communities; resources - particularly time; and the network's role in promoting innovation and shared learning. Key barriers include short-term, top-down, and monetary agency foci; conservation framed as the principal domain of specialists and professionals; and prioritisation of listed species rather than local species more broadly. We present a framework for considering scaling of biodiversity stewardship and related factors.