Rootcubes? Growing Medium offers a versatile system that has multiple applications for those crops that require high water usage. Hydroponic seed germination and foliage plant propagation are good examples. This medium is designed to drain off excess water from the base of the cutting or seed, yet provide for the proper balance of air/water needed for good root development. Rootcubes? are commonly used for hydroponic lettuce, tomato, herb and onion seed germination.