Bloody Dock (Rumex Sanguineus) An attractive plant that is also an edible herb, great for the water garden or the vegetable garden! Bloody dock has long green leaves with rich, burgundy veining. Grows 8 - 12 inches tall in up to 1 foot of water at the edge of your pond or moist garden or bog soil. Bloody Dock blooms in summer with tiny, grey-green star shaped flowers. Flowers can be cut back so you can enjoy the foliage all summer long. Bloody Dock is a perennial plant and cold tolerant. Plant in part sun-part shade to add texture and unusual color to your water garden feature.