G-Rex is formulated to be used throughout the entire growth cycle. It will continue to work from the rooted cutting stage all the way until harvest. When making cuttings, add G-Rex as soon as callus forms at the base of the cutting. After transplant, continue to use G-Rex in your system at the recommended rate through harvest. G-Rex is compatible with any fertilizer product, however, G-Rex is developed for use with Cutting Edge Solutions Fertilizers.