Urban trees provide substantial ecosystem services, and trees on private land are a sizeable segment of overall urban tree cover. Trees provide shade, cooling and habitat, and contribute to aesthetic values, sense of place, and urban dwellers’ mental and physical wellbeing. With increasing size and density of cities, tree cover decreases, as buildings replace private open spaces. As a result, there is intensifying focus on establishment and maintenance of trees in public spaces, through street tree establishment, and in public open spaces. There has been less research on tree cover in private open space in areas of increasing residential density. This research focuses on the influence of development density on urban trees on private residential land. Specifically, we analysed the relationship between dwelling density and the proportion of available land that is used for trees. Available land within residential properties may be used for a number of different purposes, including tree cover, garden beds, paved surfaces and so on. Our analysis utilised data on recent multi-unit residential development and GIS-based analysis of aerial photos of inner city areas in Melbourne, Australia. We found that with an increase in development density, tree cover increases proportionally compared with other private open space uses. Changes to soft landscaping cover had greater impact than development density on the proportion of tree cover in private open space. Our research can be utilised by policy-makers seeking to maximise urban tree cover. Further research could examine the social and policy influences on hard and soft landscaping practices.