For Vegetative Growth in Hydroponic Systems 3 - 2 - 6 Based on our popular Grow Big® Liquid Plant Food, Grow Big® Hydroponic Liquid Plant Food is a liquid concentrate fertilizer specifically designed for hydroponic use. Grow Big® Hydroponic contains earthworm castings, Norwegian kelp and essential micronutrients to support vigorous vegetative growth. Our special brew is designed to enhance plant size and structure, allowing for more abundant fruit, flower and bud development. Hydro tip: When plants show their first sign of flowering, usually around week 5, switch to Tiger Bloom® and Big Bloom®. For best results, refer to the FoxFarm Feeding Schedule.