Espoma® Organic Perlite is 100% Perlite with no additives. Perlite is one of the components in most potting soils and is the tiny white pieces that look like styrofoam. It loosens and aerates the soil and prevents compaction and promotes root growth. Espoma® Organic Perlite can be used for seed starting, or for blending your own custom potting mix. When creating your own mix combine two parts Peat Moss with one part compost and 1 part Perlite. For seed starting use a blend of 80% Peat Moss and 20% Perlite.