These materials generally increase the aeration porosity and drainage yet decrease the water-holding porosity of media.
Inorganic components are usually inert materials characterized by a low cation exchange capacity.
Vermiculite Grades Vermiculite Vermiculite is a commonly used inorganic media component which is mined in the U.S. and Africa. The production of steam results in a pressure that expands the material, increasing the volume of the pieces 15 to 20 times their original size. Vermiculite is sterile because of these high heating temperatures used during processing. Because it compacts readily when combined with heavier materials, vermiculite is sometimes recommended more for propagating material than container media. Vermiculite can fix ammonium into a form that is not readily available for plant absorption.