Sun Gro® Horticulture has long set the standard for the industry to follow in professionally formulated growing mixes. They formulate their mixes to give consistent results in every bag and bale. Mix #4 is recommended where high air capacity and fast drainage are needed with water and salt sensitive crops, or where frequent leaching is required. Ingredients: Canadian Sphagnum peat moss, coarse perlite, starter nutrient charge (with Gypsum), dolomitic limestone & long-lasting wetting agent.