This invention is related to a new substrate (6) for soilless cultivation consisting of a three-dimensional reticular structure which is elastically compressible, with empty cells bounded by threads made of polymer or any other material which are chemically inert, hydro-phobic or weakly hydrophilic. For example, the substrate which consists of a lattice made of threads in polyethylene (6) compressed into a container (4) equipped with an irrigation system(3) and with a support (2) where the plants have been inserted (5). The system is a closed cycle wherein the stored solution (1) is recirculated.