Brunnings Vermiculite is the perfect medium for use in potting mixes, seed raising and hanging baskets where its light weight and water holding characteristics are valued. It is a clean, sterile, naturally occurring, non-toxic aluminium iron silicate mineral thathas been super heated to a high temperature to produce a lightweight material with a high surface area, ideal for propagation. Ideal for aerating potting mix, garden soil and hydroponic mediums. Helps moisture retention in sandy soils and aeration of clay soils. Ideal for growing fine seeds.