Opus Mix ZERO is the ideal base potting soil blend for professional growers. Made primarily with an equal blend of coir and perlite, we add a little extra of our own special ingredients and mycorrhizae for a very special blend that only comes in Opus Grows and made in-house in Eugene, Oregon. Use as a professional style potting soil in patio planters and boxes, and all types of cloth grow bags or polycan grower containers. Add your own unique blend of nutrients during each stage of growing. Opus Grows Mix ZERO is OMRI listed and approved for organic growing.