Grodan Grow-Cubes, 5.3 cu ft (loose in box)This loose fill, non bagged product consists of small stonewool croutons about the size of a fingernail. When you use this potting mix the miniature cubes stack on top of each other and air pockets are created throughout the pot. Growcubes are difficult to overwater if the container has good drainage. The Grow Cubes are a lightweight alternative to your regular potting mix. You can use Grow Cubes in any size pot and in many different growing systems,