In this study, the effect of water stress on the germination rate of the seeds of nine pieces of species used for landscaping works in Kastamonu is investigated. The seeds of these species have been subject to germination trials with water stress level between 0 and -8 bar and the germination percentages of the seeds have been identified. The water stress was constituted with the use of polyethylene glycol (PEG-6000) solution and germinations were carried out at 25ºC in a period of 35 days. Depending on the water stress as a result of these studies, it has been stated that the percentages of all species have decreased as from -2 bar water stress; there are no germinations in -6 bar water stress for the tree of heaven, and in -8 bar water stress for Cupressus arizonica and Sophora japonica. We found that the species most resistant to water stress are Pinus nigra, Cupressus sempervirens, and Pinus brutia.