Premier®PRO-MIX® HP Mycorrhizae™ High Porosity Grower Mix 2.8cu ft Loose Fill Bag High porosity peat-based growing medium. Ensures optimum growth, especially when high air capacity and extra drainage are required. Contains Mycorrhizae™, a beneficial endomycorrhizal fungus that increases resistance to stresses and plant survival related to transplanting, nutrition and drought and increased crop vigor, plant quality and quantity of flowers/fruits.