Healing gardens are green spaces designed to promote and improve health and well-being for people suffering from illness. This paper proposes a methodology for defining a master plan for healing gardens. The methodology is based on site analysis (identification, limitations and potentials of the area) and the evaluation of user needs (patients, staff, relatives). The aim of the master plan is to provide guidelines for the definition of the executive plan, and to set up a sufficiently flexible project suitable for future new categories of patients, according to the different needs of the regional health authorities. The methodology has been applied to a case study: this paper considers the design of the healing garden of a building named Villa Bianca, part of the wider complex of the clinic for mental disorders Villa di Salute located in Trofarello (in the province of Turin, Piedmont, Italy). The main kinds of disturbances treated at Villa di Salute are schizophrenia and personality disorders; there are also some patients with severe depression. At the present time the building and the garden of Villa Bianca are not being used and are undergoing renovation.