Our popular Grow Big Liquid Plant Food is available in a special formula just for hydroponic systems. This is a potent, fast-acting, water soluble fertilizer that encourages vigorous vegetative growth from the first week through bud set. We add earthworm castings and Norwegian kelp into this special brew to encourage sturdier, healthier stems and leaves, but we 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.