August 21, 2015
By Donna Legare
Garden pond at Native Nurseries using all native plants. Photo by Donna Legare
A garden pond is a tranquil spot, bringing the relaxing sound of cascading water to a landscape while providing excellent habitat for wildlife. Plants are of utmost importance in creating a healthy garden pond.
There are two categories of underwater plants – submerged and deep water aquatics. Both survive and thrive with their roots under water or in permanently saturated soil.
Submerged plants have underwater leaves. Two of the best submerged plants are hornwort and tapegrass. Both provide cover and breeding habitat for fish, frogs and other wildlife. They help oxygenate the pond, releasing oxygen from their leaves as a by-product of photosynthesis. Oxygen passes directly into the water, enabling the water to support other life forms.
Hornwort is a free floating plant and is purchased by the handful and released to float loosely in the pond. Tapegrass, purchased in small pots and placed on the bottom of the pond, is a graceful underwater flowing grass for sun or shade. Both will multiply and need to be thinned periodically.
Deep water aquatic plants have roots and flexible stems which are submerged, but leaves and flowers must float above the water. Good examples are water lilies, which must have sun in order to bloom well.
In addition to providing habitat, underwater plants also absorb nutrients (from pond fish) that are dissolved in water thereby competing with algae. Probably more important in the control of algae is the shade that water lilies and other plants provide. Good advice is to plant your pond with enough aquatic plants to cover sixty to eighty percent of the pond’s surface. However, remember that algae is a fact of life for a water gardener. It cannot be totally eliminated, but can be controlled through creating a balanced ecosystem.
Your pond should also contain marginal plants that inhabit shallow water or the edges of a water garden. They provide vertical contrast and cover for birds, aquatic insects and other small creatures. It is important to position marginals in the depth of water that best suits each individual plant. Most grow quickly; you may need to control growth by isolating them in planting beds or in pots.
Some good examples are lemon bacopa, lizard’s tail, duck potato or arrowhead, pickerelweed, rush, Howie’s sedge, cardinal flower and blue flag iris. Lemon bacopa is a low growing, mat-forming perennial found on saturated soil or shallowly inundated. It has bright blue flowers in summer and what I love most about it is its lemon scented foliage. Another favorite is cardinal flower, with its brilliant red flower spikes that hummingbirds visit in summer. This can be planted at the edge of the pond or kept in a clay pot sitting in shallow water. Want butterflies? Plant pickerel weed with its lovely purple blossoms.