What are the psychological and cognitive wellbeing benefits as reported by people experiencing green space? A meta-ethnography

•Meta-ethnography synthesising 23 studies spanning eight countries.•11 themes translated into third order constructs, including negative experiences.•Constructs juxtaposed and grouped to form an explanatory theoretical model.•“Sense of self & others” contributes to eudaimonic wellbeing, moderated by “agency”.•“Altered thinking” aids hedonic wellbeing, mediated by “emotional processes”.•A sense of self and others is important for mental wellbeing in green space.