Jacks Classic No.1.5 17-6-6 Acid Special Fertilizer. Perfect for greening up all acid loving garden and houseplants. Feeds through both the roots and the leaves. Jack’s Classic Acid Special 17-6-6 is very effective in reducing the soil pH, which keeps iron and other trace elements available to the plant. In plantings next to the concrete foundations of the home, where the pH is elevated, it will keep the leaves green and healthy, promoting lush vegetative growth and better blooms. This formula contains elevated levels of iron and sulfur which most of the acid loving plants require.