Planting the areas in and around ponds makes them look more natural and provides an essential component in a biological system. If you plan to keep fish in your pond, the right plants create shelter for breeding and safety. It also provides essential water oxygenation. Ponds also give the gardener an opportunity to grow beautiful and exotic-looking plants that could never survive in a traditional perennial border or garden plot.
Flowering Water Plants
Water flowers sparkle in the pond habitat, providing color and accents. Plant water lilies (Nymphaea) and lotus (Nelumbo) in still waters on the end opposite a waterfall or aerator in a fish pond. Waterlilies and lotus may be hardy or tender tropical plants that come in shades from purple and reds through pastel pinks and peach to yellow and white. Water hyacinth (Eichhornia crassipes major), white milkweed (Asclepias lanceolata), and American violet (Viola spp.) are just a few of the dozens of flowering plants that can be anchored in pots or soil on the bottom of backyard ponds. Their cultural needs vary; lotus need full sunlight and tropical water lilies tolerate shade, for example. Always purchase plants based on the mature size of trees and shadows of buildings adjoining your pond.
Flowering plants and foliage plants help consume the nitrates and carbon dioxide produced by fish and other aquatic life. They use these chemicals to produce new plant tissue and discard unneeded oxygen in a process called transpiration. Floating oxygenators like water lettuce (Pistia stratiodes) and water fern (Salvinia minima) provide shade that discourages algae formation as well as providing oxygen and shelter for aquatic life. Rooted foliage plants like arrowroot (Sagittaria latifolia), water celery (Oenanthe), hardy eel-grass (Vallisneria) in pots prefer still or slow-moving water. Duckweed (Lemna minor) is a fast-growing floating oxygenator that can become invasive unless you have fish---they think it makes great salad.
Lawn grass is hard to maintain on pond banks, so pond-keepers often limit its use on the margins around their water gardens. Marginal or stream-side plants tolerate wet soil well and often grow into the water's edge, joining water and shore. Grow native plants like cardinal flower (Lobelia cardinalis) and bog bean (Memyanthus trifoliate) in shallow water or along shorelines. Cattails (Typha), Japanese iris (I. kaempferi) and pickerel weed (Pontederia) are attractive, low-maintenance bank-dwellers. Low-growing, deep-rooted sedges and moisture-loving ornamental grasses to protect moist soil against erosion. Use tolerant perennials like thyme, daylilies, purple coneflower and other native plants to blend the pond's margins and the surrounding landscaping. Some plants can become invasive and choke out others; always check with your local university extension or natural resources agent before planting something that "spreads quickly". Purple loosestrife, for example, is a marginal plant that is so successful in overwhelming native vegetation that its use has been outlawed in many states.