Turface is a high fired calcined clay that is one of the best additives for bonsai soil mixes or any other soil mix that requires moisture retention as well as great drainage. Due to its rock like consistency, Turface will provide small air pockets in your soil which promotes strong root growth and water drainage. Turface is also semi-porous so it will hold water without becoming water-logged. This helps when you are determining how often to water your plants because there is a visible difference when turface is dry or wet.