Vermiculite is a naturally occurring micaceous mineral that undergoes an industrial heat-exfoliation process, causing it to expand into lightweight, absorbent, accordion-like granules. In hydroponics and soilless cultivation, it is primarily used to manage moisture levels and improve the nutrient-holding capacity of a substrate.

High Water Retention: Unlike mediums that promote rapid drainage (such as perlite or expanded clay), vermiculite acts like a sponge. It absorbs and holds moisture within its layered structure, releasing it slowly to the root zone.