The most important issue is the to use of urban space to increase the number and size of green areas. As well as another important issue is to work towards maintaining these spaces. One such important effort is to meet the water needs of plants. Naturally, the amount of water needed by plants depends on the species. In order to successfully implement modern irrigation techniques in parks, gardens, rest and recreation areas, both direct calculation methods and estimation methods from climate data are used in determining evapotranspiration. In this study, climate elements based Penman-Monteith equation is used to investigate the water consumption, irrigation water need, irrigation interval and irrigation for the grass plant in park areas located in three different climate zones (Antalya, Ankara and Trabzon) in Turkey. The result of calculations, using the climate data of July, value of the province of Antalya were ETo=7,10464 mm/day, for Ankara ETo=6,77215 mm/day, for Trabzon ETo=4,03544 mm/day. The study also reveals the importance of identifying the water consumption needs of plants while preparing irrigation projects.