Pumice is a light siliceous vesicular volcanic rock that is suitable for use in horticulture and hydroponics. Its porosity provides air spaces that maintain aerobic conditions around the roots while water is contained within the pores. Surface tension around the outside of the pumice particles increases water-holding capacity of the growing medium. Pumice is a popular growing medium for Cacti, Succulents, Bonsai, Orchids and many other plants.
