While numerous plant types are available for growing in, around, and adjacent to water gardens, few are more fish-friendly than submerged water plants. As their name implies, these plants grow beneath the water surface. In so doing, they absorb harmful nitrites and nitrates and give off oxygen, which fish need to survive.
Here are a few of our favorite submerged water plants to consider for your garden.
Submerged Water Plants
CANADIAN PONDWEED (Elodea canadensis) The diminutive, darkish, red-green fern-like leaves on pondweed's delicate branches create the perfect cover for spawning fish. The foliage also makes a nice meal for fish, especially over winter. Pondweed grows quickly. In fact, the plant may need occasional thinning with a pond rake. One of the best and most reliable of the submerged plants, pondweed competes with algae for food. Plant it 6 inches to 5 feet below the water surface, depending on water clarity. It thrives best in full sun but will tolerate some shade. Weight the pot down with small stones in order to keep it on the bottom. Hardy in zones 4 - 10.
HORNWORT (Ceratophyllum demersum) Also called coontail, the slender stems of hornwort grow up to 2 feet long and carry whorls of feathery, densely forked leaves. The effect of the stems and leaves is similar to that of a bottlebrush. Hornwort tolerates more shade and deeper water than many other submerged plants and is highly recommended for water gardens. It is a rootless floater during the summer, and it anchors itself to the bottom during winter. Plant it 2 - 4 inches below the water surface in sun or shade. Hornwort is hardy in zones 4 - 10.
CURLED PONDWEED (Potamogeton crispus) The narrow, translucent, stalk-free leaves of curled pondweed feature wavy edges that resemble seaweed. Each leaf grows to about 3 inches long, but its stems can grow disproportionately up to 14 feet. Its use is therefore usually restricted to larger water gardens. In the spring, the plant develops small, pink-tinged flowers. Curled pondweed can be invasive in some situations, so you may have to watch it carefully. It does best in a pond with moving water rather than in a still pond. It will tolerate cloudy water. You can plant it as deep as 3 feet. The best site for it is in full sun to partial shade. Curled pondweed is hardy in zones 4 - 10.
CABOMBA (Cabomba caroliniana) Also called fanwort, cabomba leaves vary with the species. Most have bright green underwater foliage of graceful fans and tiny white flowers in summer. The foliage makes a great spawning area and a safe haven for young fish. Plants do best in cool water up to 30 inches deep. Avoid planting in warmer shallows. Cabomba grows up to 8 inches in length. Plant it in coarse, sandy soil 2 inches deep and submerged under 1 foot of water. It likes filtered light but tolerates part shade to full sun. Plants are hardy in zones 5 - 10, depending on the species.
WATER MILFOIL (MyriaphyRum spp) Water milfoil has long, trailing stems that grow from 6 to 20 feet long with tufts of fine, feathery foliage in green or brown. It provides good spawning areas for fish and is a good plant for trapping debris. Its stems extend above the surface with spikes of tiny, pale yellow flowers. Some varieties produce flowers on the water surface. They sway attractively in moving water. Water milfoil does well in shallow water or small ponds. Plant it 12 - 30 inches below the water surface in full sun to partial shade or filtered light. It is hardy in zones 4 - 11, depending upon the species.
WILD CELERY (Vallisnsria americana) Also called ribbon grass, eel grass, or tape grass, wild celery has attractive, ribbon-like leaves that reach 1 - 3 feet in length. The leaves sway in moving water. 'Spiralis' is a dwarf cultivar that grows to only 8 inches in height and is suitable for small ponds and containers. Wild celery is tolerant of warm water, and it will spread to form a pleasant carpet across the surface. Itís an excellent source of food, shelter, and shade for fish. The plants produce greenish flowers all season long, and they are an ideal natural filter for the garden pool. Plant wild celery in water that is 12 - 24 inches deep. Grows in full shade to full sun, and it is hardy in zones 4 - 11.