Granulation: "Medium" - suitable for smal volumes of substrate or casing.

Vermiculite is made from a naturally occurring mineral - mica. Crushed mica containing water is heated and expands to a volume several times greater than that of the untreated mica. Vermiculite is able to hold several times its own weight in water and it gives the substrate an airy structure.

Perfect for mushroom substrate and casing layer.