FoxFarm's extremely popular Grow Big Liquid Plant Food is also available in a special formula just for hydroponic systems, Grow Big Hydroponic Plant Food. Fox Farm Grow Big Hydroponic is a potent, fast-acting, water soluble fertilizer that encourages vigorous vegetative growth from the first week of growth through bud set. FoxFarm adds earthworm castings and Norwegian kelp into this special brew to encourage sturdier, healthier stems and leaves, and 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, blooms, and fruits.