[header] How to grow hydroponic mushrooms [title] Purchase a mushroom growing kit from your local gardening supply store. [step] Kits are blocks of compressed sawdust that have been saturated with mushroom seeds. [title] Immerse the mushroom block in a container of cold water. 
[step] Make sure it is completely immersed; allow several inches of water to cover the top of the block. [title] Allow the block to soak for several hours.