Perlite is a lightweight, porous volcanic glass that has been heated to extremely high temperatures until it expands into white, popcorn-like granules. In horticulture, it is used as a growing medium or amendment to improve drainage and aeration. Perlite is chemically inert, pH-neutral, and does not decompose β making it suitable for both soil blends and hydroponic systems. Its porous structure holds a small amount of moisture while allowing excess water and air to flow freely around roots.
Key Facts
- Made from expanded volcanic glass β lightweight, sterile, and pH neutral
- Excellent drainage and aeration properties; does not compact over time
- Common uses: mixed with coco coir (70:30 coco/perlite), soil amendment, standalone drip medium
- Holds approximately 20% water by volume while allowing oxygen access to roots
- Reusable after sterilisation between grows
- Fine perlite can be used in NFT channels; coarse perlite suits deep drip and Dutch bucket systems