Handful of perlite

About Perlite

Perlite is a soilless growing medium and soil conditioner. It is made from hydrated volcanic glass, raw perlite, that is rapidly heated until it melts. Rapid vaporization of water within raw perlite causes it to pop similar to popcorn. This causes it to expand to up to twenty (20) times its original volume. The result is an inert, sterile, light, airy and highly permeable material. This material is known as expanded perlite or simply perlite.

Perlite’s physical and chemical properties makes it an excellent an hydroponic growing medium. It provides superb root aeration and its rough surfaces promotes healthy root growth.

Perlite is also used as a soil conditioner to “cut” dense potting mixes providing lightness, aeration and drainage. It can also be used to cut water retentive soilless growing media such as cocopeat and vermiculite.

Mixture of coco peat and perlite in a fabric pot.
Coco-perlite mixture in SmartPot.

Perlite does not hold water as well other growing medium. Its spongy appearance gives it high permeability. However, the rough micro-surfaces of perlite gives it a high surface area from which water adheres. In this manner, perlite provides moisture, nutrients and oxygen to plant roots.

Close up picture of perlite
Macro picture of perlite showing its coarse and porous appearance.

Because Perlite is sterile, it makes for an excellent rooting medium for cuttings. The moist, well-aerated and sterile conditions it provides makes it easier for cuttings to strike roots.

Perlite tends to float on water and can easily be blown away by strong winds because of its very low density. It can be problem for manually irrigated or fertigated grows. This however, is not an issue for drip systems or other similar hydroponic setups.

Perlite is a non-renewable resource. We recommend using it responsibly or use eco-friendly alternatives such as pumice.

Learn more about perlite in the video below from Happy Grower’s Channel. The video is in Filipino with English transcript coming soon.

Happy growing!