Coco coir has been traditionally used as a liner for hanging baskets and containers. They help to maintain the moisture in them, and it does the same job when added to a potting mix. This by-product of coconut processing is just a finer version of that used to line baskets and has been used in hydroponic growing for a while. This fibrous, dark brown material could be mistaken for soil, and it is used in a lot of commercial potting soils. This all natural and organic material is an absorbent addition to any soil mix that adds great soil retention and drainage to the mix. It is a sustainable replacement for peat and makes a fantastic medium to grow seedlings in as it is easy for them to support the root systems of young plants.