Premier PRO-MIX® HP Mycorrhizae - 2.8cu ft Loose Fill Bag High porosity peat-based growing medium. Perlite ensures optimum growth, especially when high air capacity and extra drainage are required. An ideal formulation for growers in need of a media adapted to watering flexibility and crop seasonality. with mycorrhizae added. $30.00 each 5+ $27.00 10+ $25.00