Made with your lush and exotic plants in mind, the Miracle-Gro Tropical Potting Mix has an added element present that is not found in any of the other soils we currently carry; Scoria Volcanic Rock replaces the perlite content in this mix as they are not dissimilar but Scoria has a leg up in the competition. Perlite is created from compressed volcanic rock that is expanded with heat, giving it the lightweight, porous attributes for water absorption and aeration of the soil, but its weak structure degrades overtime as the soil compacts. Scoria has the same benefits listed for perlite, but the volcanic rock structure is much more durable, making it much more long lasting.