Palmetto Vermiculite Grade C – 3 is a medium particle size material meeting ASTM C516 Type 1, Grade 3 specifications. The material is widely used as a component in growing media for professional growers. The Greenhouse Industry uses large quantities of this material as a component of soil mix media for growers. The unique properties improve moisture retention and soil aeration and when mixed with bark provides a good growing medium for plant propagation performance.