Course grade perlite is used primarily in soil mixes. Horticultural perlite is clean, sterile, pH neutral, non-flammable, odorless, non-toxic and neither decays nor shrinks - even pests such as insects and fungi can't destroy it. When bulk perlite is mixed with organic compost, natural soils or composted bark, it helps anchor the roots of young plants so they grow stronger. While horticultural perlite does retain water and food for the growing plants, it is best used for drainage purposes. A good potting soil should contain at least 25 percent perlite for proper drainage.
