PRO-MIX® HP MYCORRHIZAE™ HP - high porosity PRO-MIX® HP, with its high perlite content, provides a growing environment which benefits growers looking for significant drainage capacity, increased air porosity and lower water retention. The added benefit of a fibrous peat moss and coarse perlite makes this formulation ideal for growers demanding a superior quality product adapted to their needs for watering flexibility and crop seasonality.