Culterra Aquatic Mix is ideal for potting up water plants and re-potting old ones.Culterra Aquatic Plant  Mix is a loose soil mix that anchors the plant in position. A small bag of gravel has been added to apply to the surface of the newly potted aquatic plant which will hold the soil in place once the plant is submersed into water. The clay mix allows the roots of the aquatic plant to anchor the plant in position and at the same time take up nutrients.