I do know that aquatic iris survive well growing in 1/2"-3" sized rocks submerged in water. I know they grow bullrush and iris in baskets with just gravel/rocks in water. The rocks I think are just to hold the plant upright and in place. Cattails and numerous other wetland plants tolerant of anoxic soil conditions would also probably grow just water. The neighbor has a greenhouse where he raises hydroponic lettuce and the root mass gets to be 12"-16" long from mature lettuce roots growing in the dark with just water around it.
Last edited by Bill Cody; 02/05/13 12:12 PM.
