In soil-less culture, the small water retention capacity of the root medium implies a high watering frequency with a discontinuous rhythm during the day. For this reason, the study of models of the water consumption is necessary. These models can be employed for the water management of gardens, to allow sustainable maintenance, by using climate sensors to record the climatic parameters. Considering water consumption equivalent to transpiration (E), the modified equation proposed by Penman-Monteith [E = A f1(LAI) G + B f2 (LAI) VPD] can be used for its estimation. This equation is composed by a radiation component (G) and an advective component (VPD), related to the leaf area index (LAI). The trial was carried out for two years in a buried greenhouse where external radiation, temperature and humidity were measured continuously using a Q20-B sensor and a RTV-5B sensor. In order to estimate the leaf area, the length (m) and the maximum width of each leaf of all the plants used in the trial were measured twice a month. Besides, the regression equation previously established was applied, introducing the experimental estimation coefficient in a random sample of 50 leaves; length, width and area were measured using a leaf area meter Delta-T. As parameters A and B are related to LAI, they depend on the species and show the following values for Dieffenbachia amoena 'Tropic Snow': A = 0.25 (adimensional) and B = 0.016 kg h-1 m-2 kPa-1 (values obtained through multivariate regression with a determination coefficient of 0.92). These results allow the use of the water consumption model for irrigation management in commercial crops.