Ultra Tech Premium Horticultural Vermiculite, Fine GradeIf you are growing an organic crop and looking for an OMRI listed and CDFA product that will provide maximum yield, then look no further! This Fine Grade Horticultural Organic Vermiculite will keep the soil from clumping, making it easier for roots to develop. This is great when used as a top dressing in seed germination. Provides added water retention in both the mix and on top of the trays. Vermiculite is an essential element that promotes healthy