When incorporating plants into your garden pond, there are several types that you can use. Lilies, bulrushes and cattails are typically contained in pots below the water's surface and use nutrients found in the soil of those pots. A second type of pond plant, known as a floating plant, uses no soil. Here is a look at some of these floating pond plants.
Duckweed is an extremely invasive floating plant that is spread from pond to pond on the feathers of flying ducks and swans. In summer, duckweed may spread to cover a pond completely. Once duckweed has covered a pond to the point that no light can penetrate below the pond's surface, it may rob the pond of all oxygen and kill all life within that pond. This is a condition known as fish kill. Duckweed only becomes invasive in small ponds that do not experience seasonal turnover. In these ponds, nitrogen becomes trapped in the pond, creating an environment for duckweed to thrive.
Parrot feather is another floating plant that has become invasive in some ponds and is often considered a weed. Parrot feather gets its name from the featherlike leaves that are arranged around the stem in whorls of 4 to 6. Parrot feather floats on the surface with leaves that rise above the water as well as those that stay submerged. The submerged leaves are generally darker than the emergent leaves. Emergent leaves may grow up to a foot above the water, resembling small fir trees. In carefully cultivated ponds, parrot feather can be quite attractive. However, parrot feather that has been planted in the wild provides a place for algae to propagate. This changes the physical and chemical characteristics of lakes and streams.
Like parrot feather and duckweed, water lettuce makes an attractive free-floating plant in garden ponds, and an invasive interloper in wild lakes of the southern United States, particularly Florida. The plant consists of up to six light-green leaves in a rosette shape. Water lettuce remains upright through a series of trailing, feathery roots that are submerged underneath the plant. Water lettuce reproduces through sucker plants. Because of this, water lettuce can cover a lake with a dense mat of rosettes in a short period of time. Water lettuce must have moist roots and warm temperatures. It can survive in mud, though it prefers to float in water. It can endure temperatures as low as 59 degrees F. The optimal growing temperatures are between 72 and 86 degrees F. Because of this, water lettuce is an annual in colder climates.