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There is growing interest in using the vegetation in the urban environment as an element that contributes to climate control. Traditionally, in warm areas, vegetation has been used to protect from direct sun lowering the temperature and increasing humidity. In Spain and more specifically in the southeastern Spanish and areas around the Mediterranean, the concept of urban "naturation" is starting to enter, although there are numerous barriers to using vegetation as an element for passive climate control in buildings. In the Mediterranean regions (arid and semi-arid), extreme weather conditions, and the scarcity and poor quality of water, requires to minimize the use of irrigation water for gardening. To ensure the survival of the facades and ground cover is necessary to optimize water consumption. The aim of this study was to quantify the water needs of green roofs planted with native and naturalized plants located in the southeastern Spanish to ensure their survival, and to know the effect on temperature for their use as insulation of roofs of buildings. The water consumption can be minimized by tailoring the dose to water demand system. To achieve the following parameters were considered: the incorporation of drip irrigation, the dose calculation based on the local evapotranspiration, the use of flora adapted to climatic conditions (native and naturalized) and the physical characteristics of the material used as substrate (water reserve). Three watering treatments were applied according to three coefficients as a function of evapotranspiration and water retention capacity of the substrate. The experiment results indicate that green roof gardening in our latitudes demands considerable water consumption, more than 200 mm year(-1). This means that the implementation of irrigation systems in the design of an extensive green roof must be considered, and it could be consider that 52% v/v minimum substrate water content, even when using native and xeric plants naturalized, to ensure the sustainability and survival of roofs. With regard to the capability of controlling the temperature of the covers, the results show that significant differences were observed in maximum temperatures, being lower below the landscaped surface, however the minimum temperatures are not significantly affected.