A plant growth system is provided in which an irrigation device provides water and/or nutrients to a plant growth substrate. The plant growth substrate comprises an MMVF slab and a single MMVF block on a first surface of the MMVF slab. The MMVF slab comprises a drain hole which is disposed at one end of the surface, and the irrigation device provides water and/or nutrients to the substrate at a position more than 50% of the length of the slab away from the drain hole. This improves the control of water an nutrients in the slab as a whole.
