Sol Soils offers a variety of high-quality soils, soil components, and soil toppers designed for potted cacti, succulents, and houseplants. We select and hand-mix the best ingredients to produce fast draining soils that help protect against root rot, the number one killer of indoor plants. Pumice (filtered 3/8" to 1/4" in size) is relatively lightweight volcanic rock used as an amendment in all types of soil. Its porous composition allows it to retain moisture and nutrients during watering, and release them slowly over time as the root system requires. Think of these components as little batteries for your plants!