Vermiculite is a natural mineral that comes from Mica rock. Thanks to its vast surface area it is able to hold many times its own weight in water and so is an ideal substrate if you need to retain nutrients around the root zone. However Vermiculite comes into its own when used in conjunction with Perlite, which does not retain water well. A 50/50 mix is a popular combo that retains moisture but also allows plenty of oxygen to get to the roots. It is ideal for use in drip systems such as Wilma’s or in flood & drain systems like Autopots, AquaFarms or IWS.
Green’s supply the V3 or Medium grain type of Vermiculite which is fibre-free, completely non-irritant, inert, incombustible, non-abrasive, rot-proof, odourless and clean to handle without the slightest danger to face of hands. However, as with all fine materials, avoid inhalation of dust.