The grow bag comprises a growing medium in the form of a slab 7 positioned within a wrapping 3, the growing medium slab comprising an inorganic substrate 9 and a plurality of biochar pieces 11, wherein the biochar pieces are dispersed throughout the slab. The inorganic substrate may be mineral wool or perlite and the grow bag may be soilless. Also disclosed is a method of manufacturing the grow bag and a method of providing a growing environment by introduction micro-organisms into the bag
