Abstract: A method and apparatus for growing plants (P) hydroponically includes a plant substrate material (52, 54, 56) comprising activated carbon and/or carbonized fibers with or without additional, non-carbonated, non-activated cellulosic fibers. The activated carbon and/or carbonized fibers with or without the additional, non-carbonated, non-activated cellulosic fibers are usable in bulk or manufactured into slabs (56) or other configurations by any of a variety of non-woven, woven, molding, or other techniques. The activated carbon and/or carbonized fibers are made from cellulosic or synthetic carbon fibers, for example, bamboo fibers.