Epsom Salt, or magnesium sulfate, is one of our "secret" ingredients for growing healthy robust plants. Tomatoes, peppers, eggplant, and roses are heavy feeders on magnesium. Sprinkle 1-2 tablespoons around your garden plants and herbs to give them a boost. The crystals dissolve slowly over the course of 1-2 months. Epsom Salt is sold in a 1/2 cup bags.