Keep your large, long-term crops happy and healthy with these slabs. Each slab is made of molten rock spun into soft, cotton candy-like fibers that have been compressed to support plant growth. Grodan is a unique growing material in that it has a great capacity for absorbing nutrient solutions while retaining large amounts of oxygen for rapid plant growth. These slabs are ideal for plants with extensive roots, such as peppers, tomatoes, or cucumbers. You can even use the slabs as growing media for hydroponic systems. Slabs drain quickly thanks to their vertical fibers, which help prevent root rot in plants. The 12 slabs are packed in UV-resistant poly sleeves, making them incredibly easy to use. Yield a bigger, healthier crop from your backyard garden, or increase the production of your greenhouse, thanks to these unique Grodan slabs.