A soilless plant growth device characterised in that it consists of a sandwich construction comprising three main portions, namely an intermediate portion (1) forming the medium and covered on one side by a carpet of vegetable matter (2) and on the other side (3) by a sealing sheet or plate. The substrat contains a grid-like reinforcement. The basic reinforcement is obtained by combining two grid-like sheets of which one remains planar while the other is wavy so that the resulting reinforcement has a certain volume that in turn defines the volume of the growth medium.
