Perlite
Porous, hard white granules of a treated volcanic rock mineral, usually mixed with potting soil to improve drainage and promote moisture retention.
Additional Information
The treatment begins when the mineral, expanded to 7-15 times its original volume by a heating process, forms the light granules. When added to soil perlite reduces the weight of the soil, a point of great benefit when dealing with very large containers. There is, however, no nutrient value.
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