Enhance Soil Aeration & Moisture Retention with Viagrow Premium Coarse Vermiculite Viagrow Premium Coarse and Chunky Vermiculite is a natural soil amendment designed to improve moisture retention, aeration, and nutrient delivery in potting mixes. This high-quality vermiculite supports better root development, faster growth rates, and higher yields by naturally holding and slowly releasing essential nutrients such as potassium, magnesium, calcium, and ammonium. Viagrow Coarse Vermiculite can be mixed with peat moss, mushroom compost, cactus soil, organic soil, bark, perlite, compost, coconut coir, worm castings, and potting soil to create a customized, well-balanced growing medium.