You cannot have a Water Garden without plants. A modest water garden can be contained in a barrel or trough or you can have an elaborate pond with streams, fountains and waterfalls. Which ever one you choose, a combination of plants will not only make it beautiful, but healthy. Aquatic plants play essential roles in the pond.
Submerged plants are those that grow fully immersed in the water. They get their nutrients directly from the water thru their leaves rather than through their roots in the soil. Underwater plants play a vital role in water gardening. They compete for the nutrients in the water that promote algae growth. They provide the fish with some food. They help oxygenate the water. They also provide hiding places for your fish if they feel threatened. One bunch of submersed aquatic plant per square foot of water surface in a pond that is not overstocked with fish will keep the pond water clear. Some of the best-submerged plants to have in your pond to help keep the water clear is:
Cabomba caroliniana. Subtropical (will not over winter outside) with bright green, fan shaped, flat-leaved up to1.5 inches in diameter. Surface leaves are linear with pointed tips. It produces a charming white flower at the waterâ€™s surface. The flower is several times as large as the very tiny white bloom of Anacharis and the equally tiny purple bloom of Elodea.
Elodea canadensis. North American native (a smaller leave version of the commonly sold Anacharis) that breaks dormancy earlier than other submersed plants. Elodea is an ideal plant for preventing spring algae blooms. Plant this in soil or pea gravel. Elodea is hardier than Anacharis.
Ceratophyl lumdemersum. Coontail, Hornwort. North American native That winters well at the bottom of your pond. Buds usually break off from the mother plant and will anchor itself to a pot on the bottom of your pond and waits for spring. This dark green plant is a free-floating plant.
Egeriadensa. Anacharis. Subtropical and a vigorous grower with multi branched stems of mid-green sessils leaves that will get up to an inch long and bend back. Can be easily propagated from stem cuttings. Tiny white flowers are borne atop thin stems at the waters surface. This plant should be planted in pots of soil or pea gravel or weighted to remain submersed. Sunlight and exposure to the air dries out the plant or can turn it to mush. My fish love to eat this plant so it does not stay very long in my pond.
Myriophyllum aquaticum. Parrots feather. At the surface you will find the touch-sensitive whorls of feathery lime green leaves. These leaves can be tucked into crevices of the waterfall or ponds edge. You can also plant them in pots. The submersed leaves are sparse along with stems of 20 to 60 inches in length and are not very effective at nutrient removal. If it remains below the ice in the winter it is hardy in zone 5.
Vallisneriaspiralis. Spiral tape grass. Tropical plant that forms long ribbon like leaves from basal rosettes. It is the slender flowers stem that spirals to the water’s surface. The leaves may grow as long as 32 inches. It spreads by both runners and seed from its separate male and female plants.
All the above-mentioned plants can be potted but if you do not have the room in your pond for all those pots try and anchor them down with a rock or another pot. I have pea gravel in the bottom of my pond so most of my submerged plants are grown on the bottom. I do however anchor them with larger rocks to keep my koi from digging them up and the plants from floating to the surface and into my filter.
Darlene Jennings (pond Lady) President, Mid-Michigan Pond & Water Garden Club Advanced MSU Master Gardener