The present invention relates to a method of producing a coherent growthsubstrate product formed of man-made vitreousfibres (MMVF), comprising the steps of (i) providing MMVF； (ii) providing anuncured binder composition； (iii) providing an additive；(iv) forming a mixture of the MMVF, the uncured binder composition and theadditive； (v) curing the uncured binder composition in themixture to form the coherent growth substrate product； wherein the uncuredbinder composition comprises at least one hydrocolloid；and wherein the additive is a micro-organism, fungus, biologically-activeadditive or combination thereof.
