People often want a water feature as part of their garden design, but have no idea what plants can be used to create a pleasing design. In nature, the plants that are found in bogs, ponds, or wetlands also work well as part of a garden water feature. When possible, it is best to use native plants from your region. What plants grow in the ponds and wetlands in your part of the country? These should be the first plants to look for at the nursery when selecting plants for your water feature. When native wetland plants are not available, there are also a number of ornamental plants that are appropriate for water features and rain gardens.
Water features need plants, and this isn’t just for aesthetic reasons. Introducing plants to your backyard pond or garden water feature will help maintain the nutrient balance by absorbing carbon dioxide and minerals from the water. The absorbed carbon dioxide, in turn, starves algae, preventing your backyard pond from turning into a murky, green mess. To maintain the correct balance, about half of a garden water feature’s surface should be covered with pond plants.
When selecting plants for your backyard water feature, select plants from four basic groups. Common water plants fall into four categories, each of which is important to the health of your backyard pond:
- Oxygenators: Oxygenators are considered one of the most important groups of plants for pond landscaping. They grow rapidly at the bottom of the pond, consuming nutrients and mineral salts that would otherwise be used by algae. They are called oxygenators because they release oxygen into the pond water and provide direct competition with algae to keep your pond water clear. If you have koi or other fish, oxygenators also provide a place for the fish to spawn and lay their eggs. Common oxygenators to have in your water feature are Ceratophyllum demersum (Hornwort) and Myriophyllum aquaticum (Hardy Parrot’s Feather).
- Marginals: In nature, marginals are plants that grow in shallow water or saturated soil around the perimeter of ponds or along the banks of streams. Think cattails. In the backyard pond, cattails would not be the best choice, but these plants are planted at a depth that allows approximately 3 to 6 inches above their crowns. In a backyard water feature, there are many ornamental plants that can be placed in pots at the edges of the water feature with a few inches of water above their crowns. Common marginal plants to consider for your backyard water feature include Cyperus papyrus ‘Nana’ (Dwarf Egyptian Papyrus), Carex spp. (Sedge), Iris siberica (Siberian Iris), and Iris kaempferi (Japanese Iris).
- Floaters: Floaters are important for shading the water surface and providing hiding places for fish. Just like they sound, floaters are plants, such as water lily, which float on the surface of the water. Like oxygenators, these backyard pond plants reduce algae by competing for nutrients and carbon dioxide. Increased shading and lower light penetration keep the water cooler, which is especially important if you have fish like koi. In addition to water lilies, common floaters for your backyard water feature include Lemna minor (Duckweed), Pistia stratiotes (Water Lettuce), and Azolla caroliniana (Fairy Floating Moss).
- Surrounding Plants: In addition to the plants in your water feature, it is important that the plants surrounding the pond or water feature add to the overall design and provide additional shading to the water surface. Plants that will drop their leaves in the winter should be avoided to minimize maintenance. Ornamental grasses and rushes such as Carex morrowii ‘Ice Dance’ (Ice Dance Sedge) and Juncus effuses (Soft Rush) can be used in these locations.
Pond and Wetland Plants for a Rain Garden
As an alternative to a garden water feature, you can use pond and wetland plants to create a bog garden, commonly referred to as a rain garden. Ponding water is not essential for bog and wetland plants, but they must be located in a low-lying area where water pools and then drains naturally. The use of pond and wetland plants is ideal for areas where the soil stays moist and it is difficult to get the water to drain. Pond and wetland plants can be placed around the edges of a pond or planted in a rain garden where they will not only get sufficient moisture but will also provide vertical accents and texture contrasts.
Although many bog plants are grown for their leaves, others produce brilliant flowers that bloom during various times of the year. The following are some common plants for rain gardens:
- Iris: Irises are one of the most popular backyard plants for rain gardens. They range in height from 6 inches to 6 feet, and their flower colors vary from red to yellow to purple. These plants filter ponds and rain gardens well and can be grown in virtually any moist area. Plus, their course, vertical, sword-shaped leaves provide a nice texture contrast to the finer leaves of sedges and rushes.
- Water hyacinths: These are floating plants with upright leaves that act as sails. The spongy stalk keeps the plant buoyant and produces purple or blue flowers. Water hyacinth, considered one of the most productive plants on earth, is abundant in the Florida wetlands. It forms dense mats that significantly decrease water flow.
- Reeds and rushes: Papyrus, bulrush and pickerel are all types of bog and wetland plants that thrive in either full shade or sun. These pond plants can tolerate standing water for long periods of time and provide a fine upright leaf texture to the rain garden.
When choosing pond plants for rain gardens or garden water features, always look to nature for ideas. Observe where bog and wetland plants grow in your area. If you have a rain garden or backyard pond that mimics those conditions in nature, chances are you will have no problem finding wetland plants for your rain garden.