Cold water lime pasteurisation of sawdust pellets is an easy, affordable and efficient method of preparing bulk substrate for the growing of vigorous mushroom species like oyster mushrooms , using readily available materials. Sawdust pellets are in general a very clean substrate with low levels of mould spores or chemical residues. This method utilises the high alkaline pH of hydrated lime (calcium hydroxide) to suppress the germination of mould spores in the substrate while