The device has a bag (1) with an upper wall (3) and a lower wall (4) integrated to one another along the bag`s circumference (5) and adapted to retain a cultivation substrate (2). The wall (4) extends above the circumference along a peripheral structure (6), where the wall (4) is made up of a hydrophilic material. The wall (4) is structured in a manner so as to be permeable to the root of a plant that has to be cultivated in the device.