Ultratech Vermiculite Fine Grade 4 CU FTHorticultural Vermiculite is a valuable growing medium for small area gardening and hydroponics. A 50 50 mix of vermiculite and perlite is a popular medium for drip hydroponic and ebb and flow systems. Mixed with natural soil, peat, organic compost, or bark, it will hold moisture, retain air, and provide plant food with a minimal amount of water required. Excellent buffering for the root zone. Holds moisture and nutrients for later use. Supplies the