The soothing sound of moving water makes a pond a popular garden feature. Add plants to a pond, and you’ve created a water garden. It’s more than just a name change, however. Water plants soften and naturalize constructed water features and play a vital role in establishing a pond’s balanced ecosystem.
Water plants are an excellent natural filter. For instance, if you have fish in your pond, the plants’ primary nutrient source is the very waste the fish produce. The fish and plants have a nice partnership. In return for the nutrients, the plants provide food and shelter for the fish. Water plants are also a natural algae deterrent. They consume the nutrients algae need to thrive and their leaves add shade to the water, reducing the sunlight that makes algae grow.
There are a wide range of water plants to consider. But, selection becomes easier when you follow a few basic guidelines. Aquatic plants are grouped into categories based loosely on growth habits and their placement in the pond. Each group – submerged, floating and marginal – plays a different role in the water garden.
Submerged plants can thrive in as much as three feet of water and include the showy water lily, the delicate water hawthorn and the largely unnoticed but crucial oxygenators such as eel grass and sagittaria. While the lilies and hawthorns add drama to your pond, their less flashy peers the oxygenators are extremely beneficial for water quality. This group of plants releases oxygen into the water and competes with algae for the excess nutrients the algae needs to survive. Add oxygenators to fight the green slime that can grow in water gardens.
Fish love the cover of floating plants such as delicate fairy moss or duckweed, as well as popular water hyacinth and water lettuce. Floaters also provide an overhead smorgasbord for the fish, which graze on the snails and worms that attach to the plants’ dangling, filter-like root systems. You do need to be careful with floaters because they quickly multiply. Start with a few plants to avoid too much coverage. You don’t want your entire water surface to be covered because your submerged oxygenating plants need sunlight; your fish like the warmth of the sun; and exposed water surface allows healthy oxygen exchange.
Marginals are planted in shallow water (2-8 inches) and come in many varieties such as cattail, iris, cardinal flower and the rush/sedge family. A broad description of these plants is that their roots are underwater and their stems, leaves and flowers are above the water’s surface. While marginals are usually added to ponds for their beauty, they, too, provide shelter and filtration for pond dwellers such as fish and frogs. Birds and insects are attracted by their flowers.
When it comes time to place plants in your water feature, consider sunlight, water movement and, just as you do when planting in the dirt, heights and textures to enhance the pond’s appearance. Most water plants need sunlight to reach their potential, but there are shade-tolerant plants, including water hawthorn and marsh marigold. Consider the water movement in your pond before placing plants. For instance, water lilies prefer still water so plant them away from waterfalls and streams. Place oxygen-loving reeds and water mints in fast moving water.
Aquatic plants require little maintenance, which might be one of their most attractive features. In contrast to the weeding, fertilizing, pruning and watering terrestrial gardeners know and love, pond plants only need to be fed once a month during growing season and, of course, weeding and watering isn’t an issue. You should remove spent flowers and dead leaves and stalks to prevent the build-up of silt and algae in your pond. In the summer, sit back and enjoy the plants’ beautiful blooms and textures. When winter returns, there are at least two opinions on what to do. Some water gardeners prune their plants and place them in a deeper portion of the pond that will not freeze. Others prefer a more natural approach and leave the plants in place. In spring, if you’ve moved your plants, return them to their original placement. Aquatic plants are generally in stock May through Labor Day. Stop by to learn more about how these plants are important additions to the health of your pond … and a lovely way to add variety to your peaceful garden.