Rockwool is the most common media for rooting cuttings and seed germination. Many growers claim that rockwool cubes are the easiest method for this stage, but rockwool can be an ideal substrate for plants of all sizes because its unique structure provides a good balance of water and oxygen, which promotes healthy root growth. Rockwool should be soaked overnight to adjust the pH.The rising cost and difficult disposal of rockwool (it doesn't decompose) have led many cannabis growers to move towards clay pellets and coconut fibre. Clay pellets are made by baking clay in a kiln and are full of tiny air pockets, which give them good drainage. You should, however, flush clay on a regular basis with a flushing agent. Though pellets are rather expensive, unlike most other media, they can be reused. After harvest, be sure to sterilize and remove old roots. Coconut fibre, also known as coco or coir, has become one of the most popular growing mediums because it's an "organic" medium that provides ideal conditions for hydroponic systems.Coconut fibre is the pulverized husks of coconuts and comes in different grades. It can maintain a larger oxygen capacity than rockwool, while also holding more water and some growers say that it offers natural insect-repelling qualities. It also has low nutrient levels, and therefor won't interfere with the composition of your nutrient solutions. JUMP TO HYDROPONICS