Perlite is used to improve moisture retention and aeration in soil.   Uses of Horticulture or Agriculture grade of Perlite   Perlite's many uses and beneficial properties include:   ¤ Inorganic, inert and sterile.¤ No known toxicity or fire hazard.¤ Prevents compaction - improves aeration and drainage.¤ Does not decompose - lasts for years.¤ Stimulates root initiation and vigorous growth.¤ Insulates and minimises temperature fluctuations.¤ Almost neutral pH.¤ Holds moisture but does not become soggy.¤ Free from disease, weeds and insects.