Grow Big® Hydroponic - The Right Juice for the Right Use! Based on FoxFarm's popular Grow Big® Liquid Plant Food, this is a special formula just for hydroponic systems. Grow Big® Hydroponic Liquid Plant Food is a potent, fast acting, liquid concentrate fertilizer specifically designed for hydroponic use. When used as directed Grow Big® Hydroponic encourages vigorous vegetative growth. FoxFarm adds earthworm castings and Norwegian kelp into this special brew to encourage sturdier, healthier stems and leaves, but they also provide enough nutrients and trace minerals to create the kind of healthy branching that you’ll need later in the season for more abundant buds and blooms. Hydro tip: Beginning the first week, use 2-3 teaspoons per gallon. Maintain pH between 5.8 and 6.3. When plants show their first sign of flowering, usually around week 5, switch to a bloom enhancing plant food.