Grodan slabs come in 3 different sizes. Normally, you would place a Rockwool cube on top of them and let the roots grow into them. They are great to cut up into squares and use them for the extra root growth below cubes and to keep the plants from tipping over. It has a tremendous capacity for absorbing nutrient solution while retaining plenty of oxygen for rapid plant growth. It is made from molten rock spun into cotton candy-like fibers and then compressed into cubes, blocks, or slabs. It comes in graduated sizes. Seedlings started in cubes 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. Grodan slab is used in final stage of planting with growing blocks. These slabs come in clearly marked UV resistant poly sleeves for ease of use. Grodan slabs are recommended for larger, long term crops with extensive roots like peppers, tomatoes, or cucumbers. Typically, seedlings in blocks are placed onto slabs.
