The present invention relates to a method of producing a coherent growthsubstrate product formed of man-madevitreous fibres (MMVF), comprising the steps of (vi) providing MMVF； (vii)providing an uncured binder composition； (viii) providinga superabsorbent polymer； (ix) forming a mixture of the MMVF, the uncuredbinder composition and the superabsorbent polymer；(x) curing the uncured binder composition in the mixture to form the coherentgrowth substrate product； wherein the uncured bindercomposition comprises at least one hydrocolloid.
