Enjoy complete control over plant growth and nutrient systems with our Starter Plugs. Made from molten rock spun into cotton candy-like fibers and then compressed into blocks. Where other rockwool brand manufacturers cut all sizes from one batch of wool, Grodan is unique by making different types of fibers. The purpose is to support the requirement of the plant in the different plant stages. Grodan has a tremendous capacity for absorbing nutrient solution while retaining plenty of oxygen for rapid plant growth. Grodan comes in sheets of 98 plugs. Seedlings started in plugs are easily transferred to blocks and then onto slabs, if desired. Seedlings or cuttings started in the Grodan cubes can also be transplanted into more traditional planters and growing mediums.