A koi pond is a beautiful and enjoyable addition to any backyard, especially when enhanced with various plants. Besides adding character and aesthetics to your koi pond, plants can also be beneficial to its ecosystem.
Aquatic plants increase oxygen levels, which help keep the pond adequately aerated. Their presence also helps keep water temperatures on the cooler side during the summer and protects koi from direct exposure to the sun. Algae blooms can become problematic in the spring and summer months, and aquatic plants also help to quell their growth. Additionally, plants create natural hiding spots to help koi remain safe from neighborhood predators. For those who breed koi, they provide surfaces for females to attach their eggs.
While plants aren’t essential to a pond, they do have many benefits. Here are some examples of popular pond plants that koi enthusiasts enjoy.
Types of Pond Plants
As their name suggests, floating plants sit atop the water’s surface. Most of these plants also have free-floating roots, while some anchor to the pond’s bottom. Floating plants are easy to care for and enhance your pond’s biological filtration. They are simple to install, as you can place them directly in the water.
Water lilies are arguably the most popular plant in koi ponds. Two varieties exist—hardy and tropical—and, between the two, they are compatible with nearly every climate in the United States. Water lilies play a positive role in maintaining good water quality as they keep oxygen-hogging algae at bay and block out sunlight to give your koi shade and shelter.
As their name suggests, hardy water lilies can survive in most conditions, blooming from mid-to-late spring to early fall and lying dormant the rest of the year. Tropicals will die in frigid temperatures and are best suited for water that is above 80 degrees.
The leaves of hardy water lilies are circular, with smooth, round edges. Tropical water lilies come in different shapes, typically smooth, toothed, or fluted. Their pads are larger than the hardy water lilies, and their blooms can grow to impressive sizes. The two varieties share the same color palettes, including reds, oranges, pinks, and white or black. Tropicals also come in blue and purple.
Because koi consider water lilies tasty treats, most owners will undertake preventative measures such as installing netting systems or planting other delicious but less visually appealing plants nearby.
Despite its delicate appearance, the lotus is a hardy plant that requires minimal maintenance. It does well in moderate climates, thriving in water temperatures between 75 and 87 degrees. The lotus needs ample sunlight (at least six hours of direct exposure per day) and low humidity. Therefore, it’s not a great option in regions like the ever-moist southeast or the cloudy pacific northwest.
Lotuses come in a range of sizes. Some varieties grow leaves up to 16 inches tall on stems up to four feet long, while smaller types can form leaves just a couple of inches in diameter, connected to stems that are only about 12 inches in length.
Water hyacinths make great additions to koi ponds because they grow quickly and extensively and also are one of koi’s favorite treats. Many enthusiasts will add water hyacinth as a way to keep their koi’s tastebuds satisfied so they won’t snack on the less prolific plants. This species blooms annually in colder climates and is a perennial in warmer locations. They bear purple or blue flowers, and their roots intertwine beneath them. Water hyacinths also are powerful biological filters, soaking up the water’s excess nutrients.
Water lettuce is a perennial evergreen that grows in floating colonies. Though koi may nibble it occasionally, it is not one of their favorites. Therefore, it can require a bit of maintenance to keep from overgrowing. Water lettuce does not have as many physical benefits as other floating plants, but it is considered an attractive addition to a pond and remains one of the more popular choices. Its spongy foliage is typically bright green, and its bulbous shape (similar to a head of lettuce) makes it look like an ornament in the pond. Water lettuce does best in the warmer climates of the southeast and southwest.
The water poppy is an ornamental pond plant that grows deep green, heart-shaped leaves and three-petal blossoms in yellow. Though the flowers on this perennial last only 24 hours, they will continue to sprout new ones throughout the summer growing season. This plant is a perfect addition for shallow areas of your pond, as it grows best when submerged in about six inches of water and might not survive in water deeper than 12 inches. Water poppies can survive all year in warm climates, but you will need to bring them indoors for the winter if you live in an area that is susceptible to frost.
Shallow Water Marsh Plants
Shallow water marsh plants make great additions to koi ponds with shallow areas, usually around the edges. They provide a more natural look for the pond while also helping to improve its filtration. They need moist soil at all times, and they must have some soil on their roots.
Water iris is a highly versatile plant that can seemingly do it all. They filter the water, feed hungry koi, are hardy, versatile, and require minimal maintenance. Water irises produce beautiful flowers that come in a variety of colors. Numerous types exist and can adapt almost anywhere—from Florida to Alaska and just about everywhere in between. Water irises will require some assistance to grow and should be planted with a water-soluble fertilizer safe for koi.
The copper, or red flag, is a smaller iris that grows to about 12 inches. Its slender leaves droop slightly at the tips, and its three-inch, copper-colored flowers hang downward. The copper iris will grow well in full or partial sun and usually blooms in mid-June. The preferred water depth is up to three inches over its crown. Copper irises are hardy in colder climates and easily survive a winter frost.
The rabbit ear iris has rounded, short, upright petals. It grows to about three feet and spans about 12 inches. The blossoms are usually three to four inches wide and appear white, royal blue, or reddish-purple. The preferred water depth is up to six inches over the crown. The rabbit ear iris prefers cooler summers and doesn’t do well in exceedingly dry climates, so this is not the best choice for regions like the arid southwest.
Cube-seed iris produces early-summer flowers in white, light blue, dark blue, purple, or pink. Cube-seed iris grows to about 12 inches tall. Its blooms are only one to two inches in diameter but come in various stunning colors, including white, light blue, dark blue, purple, and pink. Cube-seed iris must be planted in the shallowest area of the pond and should only be slightly submerged. This variety can do well almost anywhere in the continental United States.
Yellow flag iris is known for its bright flowers that appear in early spring. The yellow flag has now naturalized over most of North America, growing in full or partial sun. It can live in deeper water than the other iris varieties and can withstand seasonal flooding. It also survives periods of drought during the summer. Yellow flag usually grows about three to four feet tall and has a spread of 24 to 30 inches. Blooms are typically three inches wide.
Blue flag iris produces flowers that bloom in mid-spring. It grows up to three feet tall and has a spread of approximately 12 inches. Blue flag iris can thrive in water that is three to six inches over its crown. Leaves are narrow and sword-shaped. You can find it in swamps, wet meadows, stream banks, or forested wetlands in a natural setting. However, in a koi pond, it is hardy in most climates.
Louisiana irises are hybrids of several iris varieties. They will grow in pond areas up to six inches deep but can tolerate a moderate amount of seasonal flooding. They can grow up to three feet tall, with flowers ranging between three and seven inches in rust, blue, purple, yellow, pink, and white color combinations. The Louisiana iris does well in moderate to warm climates but can survive freezing temperatures when its roots are planted in mulch.
Umbrella plants have large ribbon-shaped leaves two to three feet long, extending from stocks that can grow five feet or more in height. These plants thrive in tropical climates but can survive in most regions with a few precautions. The plants must be moved inside and placed by a well-lit window when water temperatures dip below 70 degrees. They make great additions to koi ponds as they provide a large overhanging canopy that can serve as shelter and shade. The umbrella plant is easy to care for, and it derives its nutrients from the pond water, assists in biological filtration, and enhances the oxygenating capabilities of other plants. The only downside of this plant is that it can be an invasive spreader, but spreading can be controlled by planting it in containers within the pond.
The horsetail plant produces a slender green stem and is fast growing. Botanists consider it a living fossil as it predates the dinosaurs. It is safe for koi consumption (and humans too)—it has a celery-like taste and contains various medicinal properties. Its giant stalks can reach heights of up to four feet. You will need to monitor horsetail as it can spread out of control relatively quickly. Rather than seeding, it grows through an extension of roots. Potting it within the pond can help prevent overgrowth. Able to withstand colder climates, it is an excellent option for ponds in northern states.
Submerged plants typically grow in pots that you position on the bottom of your pond. Because these plants grow all or mostly underwater, they are primarily functional rather than ornamental. These plants are highly effective at removing toxins and excess nutrients from the water while providing beneficial oxygen. Koi tend to eat submerged plants, so you’ll need to minimize their access to them.
Fanwort is a fast-growing oxygenator. These plants can climb up to an inch per day and can propagate using cuttings. Fanwort needs a lot of sunlight and won’t do well in the shade. This leafy-green plant is primarily used for functionality as it introduces more oxygen to the water, increases the level of dissolved oxygen, and enables the pond to support a more diverse ecosystem. It also serves as a good attachment plant for koi eggs during the breeding season. It doesn’t add much aesthetic to the pond as its leaves grow underwater, but it can form dense mats at the water surface. Small oval floating leaves are occasionally present at the surface and can produce white or cream flowers about half an inch wide between May and September. Some variations of fanwort have pink or purple flowers. It is an incredibly versatile plant that can grow in warm and cold climates and various water conditions.
American Waterweed (Elodea)
The American waterweed, or elodea, is a submerged, leafy green plant with small white flowers that will sprout at the surface. It is excellent for dissolving carbon dioxide in the water and limiting algae growth. It can also serve as a healthy snack for koi. The plant can grow up to four feet in length given enough space—and like a weed, it proliferates quickly—so there will be enough of it to go around. It is considered an invasive species in the wild. This plant does well in milder climates, will stay green all year, and provides a good place for koi eggs to hatch.
Water Purslane (Ludwigia)
Water purslane, or ludwigia, is typically grown as a submerged plant and can float on the water’s surface. It comes in several varieties and often produces small flowers. Red ludwigia is the most popular variety for use in koi ponds. It grows quickly, so over-snacking is not a concern, and it oxygenates the water while limiting algae blooms. Water purslane needs plenty of sunlight, especially when planted under the water. Though it is considered a weed, it can help to stabilize your pond’s ecosystem and filter toxins. Because many varieties of this plant exist, you should be able to find one that’s fit for your climate no matter where you live.
Want to add a few new fish to your backyard pond? Browse our full selection of koi and goldfish today.