Rockwool vs. Coco Coir: A Sterile Perspective

Coco is great, but it’s organic. It comes with its own cation exchange capacity (CEC), meaning it holds onto Calcium and Magnesium. That’s an extra variable in your math.

Rockwool is basalt rock spun into fiber. It is chemically inert. It holds nothing. If I pour 100ppm of Nitrogen in, 100ppm is available to the plant. For scientific growing, Rockwool wins. If you want sterile, rockwool plays nice; coco fights back.