Can You Have Plants in Your Koi Pond?

Floating Aquatic Plants

• Floating aquatic plants float freely on the pond's surface and do not need to be anchored. Essential to koi ponds, floating plants offer shade and hiding places for fish. In order to keep algae in check by limiting sunlight, approximately 60 percent of the pond should be covered with floaters. Resembling miniature water lilies with glossy, heart-shaped leaves, Limnobium spongia, commonly known as American Frogbit is an example of a native floating plant with wide distribution in U.S. Department of Agriculture plant hardiness zones 6 through 10. Because some varieties of aquatic plants can be invasive, check with your local aquatic nursery or university extension program to assist in selecting non-invasive and native plants for your pond.

Marginal Aquatic Plants

• Also known as bog plants, marginal aquatic plants are placed along a pond's edge or in very shallow water. Most water plants fall under this category and serve to beautify the pond by creating a seamless integration of pond and landscape. Place these types plants around the perimeter of your pond to keep algae levels manageable by filtering nutrients that would otherwise feed the algae. Consider carnivorous marginal plants to help keep down on mosquitoes and other nuisance insects. Two such carnivorous examples, Sarracenia leucophylla x willisii, known as Dana's Delight, and Sarracenia leucophylla 'Tarnok' are vibrantly colored pitcher plants that are hardy in USDA Zones 5a through 8b.

Oxygenators

• Oxygenators are named for their ability to release oxygen into the water and remove nutrients that algae need to grow. Also called submerged aquatic plants, oxygenators are vital to a healthy pond ecosystem and grow entirely beneath the water's surface. Submerged aquatic plants do more than provide oxygen and compete with algae for nutrients, they also provide shelter and spawning areas for fish. For an easy-to-maintain oxygenator, consider the Dwarf Sagittaria or Sagittaria subulata. Suitable for USDA zones 4 through 11, Dwarf Sagittaria is an attractive underwater grass that forms short clumps and stabilizes soil.

Deep Water Aquatic Plants

• Water plants with roots anchored to the bottom of the pond and leaves or flowers that extend above the surface are known as deep water or emergent aquatic plants. Water lilies most readily come to mind when considering deep water plants, but there are many other choices available. The relatively small and mat-forming Watershield, or Brasenia schreberi, is popular amongst water gardeners and can be found in most nurseries. Hardy in USDA zones 3 through 11, it attracts water fowl that eat its seeds and has small, dark purple flowers that bloom midsummer.