Perlite is a white, sterile propagating medium used by growers to keep soil loose, allowing air and water to reach roots. It is ideal for seeds germination, for potting plants, to root cuttings, to hold cut flower and to help establish new lawns. In horticulture, perlite can be used as a soil amendment or alone as a medium for hydroponics or for starting cuttings. All of these are natural minerals, and are often part of other soil blends. It has a pH of 6.6 to 7.5.
Perlite is quite porous. The cavities in perlite help store nutrients and some moisture that the plant might need, but drain excess water away. It is non-toxic, clean, disease-free, and extremely lightweight and easy to work with. Its has been observed that perlite will form powdery residue due to storage and tranportation and its accepted by industry standards.
Perlite is a natural filtration system, allowing excess water to easily drain away while retaining a little moisture and catching nutrients that plants need to grow. This is especially true in raised beds and container gardens, but also in the ground as well.
Airflow in the soil is greatly improved in a bed amended with perlite, and that’s necessary both for your plant’s roots to breathe and for any worms, beneficial nematodes, and other good natural garden inhabitants. Because it’s a mineral glass and thus harder than the soil around it, it also helps to slow down compaction, and keeps your soil fluffy and lightweight.