Intro

A koi pond is more than just a place for your fish to swim; it can become a peaceful, beautiful oasis right in your backyard. Adding the right plants can transform the space, creating a serene and natural environment for both the fish and the viewer. 

Whether you’re a beginner or a seasoned pond owner, the right plants can improve water quality, provide shade, and offer shelter for your koi. In this guide, we’ll explore some of the best plants you can add to your koi pond to enhance its beauty and health, making it a true aquatic paradise.

Plants to Beautify Your Koi Pond

Building a koi pond is an exciting way to add beauty and tranquility to your garden. But if you really want to create a serene environment for your koi, adding the right plants is key. In this guide, we’ll explore everything you need to know about koi pond plants, including why they are so important, the different types of plants that thrive in koi ponds, and how to maintain a healthy pond ecosystem.

Koi Pond Plants vs. Common Pond Plants: What’s the Difference?

You might be wondering, what’s the difference between koi pond plants and regular pond plants? The main difference lies in the plant’s ability to coexist peacefully with koi fish. Koi are known for nibbling on plants, so it’s important to choose species that are hardy enough to handle their curious appetites. 

Common pond plants may not be as robust, while koi pond plants are specifically chosen for their ability to withstand being grazed by fish. Koi pond plants also play a more active role in maintaining water quality by providing oxygen and absorbing excess nutrients, which is crucial for both your fish and plants to thrive.

Koi Pond Plants

1. Water Lotus (Nelumbo lutea)

Water lotus plants are the crown jewels of any koi pond. With their stunning flowers and large, broad leaves, they provide ample shade for your koi, which they love. These plants also help keep the water cool and oxygenated, which is essential for a healthy pond ecosystem.

• Light: They enjoy sunny locations.
• Type: Floating plant
• Koi food: No, koi don’t seem to like them as food.
• Invasive: Not invasive, but very large, taking up a lot of space.
• USDA hardiness zones: Thrives in zones 4 to 11
• How to plant: Pots or planting bags

2. Water Lilies (Nymphaea)

Water lilies are beautiful and functional. Their floating leaves offer shade and shelter for your koi. Plus, they bloom with vibrant flowers, adding color and elegance to your pond. Water lilies also improve water quality by absorbing excess nutrients.

• Light: Full sun to partial shade
• Type: A floating plant with roots and stems below the water
• Koi Food: Koi fish eat their roots.
• Invasive: No
• USDA hardiness zone: Hardy water lilies are hardy in zones 3 to 11 and thrive in the Northern United States.
• How to plant: Pots or planting bags

3. Hornwort (Ceratophyllum demersum)

Hornwort is an excellent choice for oxygenation in your koi pond. It’s a fast-growing, floating plant that doesn’t require soil to thrive. It helps to absorb excess nutrients from the water, preventing algae growth and keeping your pond water clear.

• Light: Full sun to soft light
• Type: Submerged, floating near the water surface
• Koi Food: Yes, it’s a tasty snack for koi.
• Invasive: Can become invasive if not trimmed from time to time.
• USDA hardiness zone: Hardy in zones 5 to 11 and overwinters well, even in cold climates
• How to plant: Just place it in the pond water.

4. Horsetail (Equisetum)

Horsetail has a unique, tall, and striking appearance, making it a favorite for many pond owners. It grows well in shallow water and offers a nice contrast to softer plants. Its upright stems help filter the water, improving pond health.

• Light: Partial shade
• Type: Marginal plant that grows in wet soils.
• Koi food: No
• Invasive: Some varieties can become invasive if planted directly into the soil and not trimmed in time.
• USDA hardiness zone: Thrive in zones 4 to 11
• How to plant: In a pot or planting bag

5. Water Iris (Iris pseudacorus)

Water irises are fantastic for adding vertical structure to your pond. Their tall, vibrant flowers bloom in a range of colors, creating a lovely focal point. They also act as natural filters, helping maintain clean, healthy water.

• Light: Enjoys full sun to partial shade
• Type: Marginal plant, grows better in shallow water, up to 5 inches, just deep enough to cover the crown
• Koi Food: No
• Invasive: Fast-spreading; can become invasive
• USDA hardiness zone: Hardy in zones 4 to 9
• How to plant: Submerged pots

6. Water Poppy (Hydrocleys nympho rides)

Water poppies have delicate, bright yellow flowers and heart-shaped leaves. They are perfect for adding a pop of color to your pond and providing some shelter for your koi. They also help absorb excess nutrients, reducing algae growth.

• Light: Likes full sun but tolerates a lot of shade
• Type: Floating, water lily-like plant
• Koi food: Yes
• Invasive: Fast-growing; can become invasive if not pruned on time
• USDA hardiness zone: It grows well in zones 9 to 11.
• How to plant: In wide, shallow pots submerged about 6 inches deep.

7. Watercress (Tropaeolum majus)

Watercress is a fast-growing plant with edible leaves that can thrive in shallow water. It provides a natural filter for your pond by absorbing excess nutrients. Plus, its small, peppery leaves are a favorite for those looking to add a bit of flavor to their kitchen!

• Light: Thrives in full sun and partial shade
• Type: Marginal plant
• Koi Food: Yes, watercress is eaten by koi.
• Invasive: Can become invasive if not kept under control
• USDA hardiness zone: It is hardy in zones 4 to 9.
• How to plant: In mesh pots

8. Water Purslane (Ludwigia palustris)

Water purslane is an excellent plant for koi ponds, offering both beauty and utility. It grows quickly and its creeping nature creates dense patches of greenery that help provide oxygen and shade for your koi.

• Light: Needs plenty of sunlight
• Type: Marginal plant that grows well in muddy ground and shallow waters
• Koi Food: Yes, koi fish eat it, and over-snacking is fine since it grows quickly.
• Invasive: Fast-growing; needs trimming from time to time
• USDA hardiness zone: It thrives in zones 3 to 7.
• How to plant: Add to the gravel/soil around the pond.

9. Water Smartweed (Persicaria amphibia)

Water smartweed is a hardy plant that grows well in both submerged and emergent forms. Its vibrant flowers attract pollinators, while its thick, leafy growth provides shade and shelter for your koi.

• Light: Prefers full or partial sun locations
• Type: Submerged or marginal, in the boggy soil near the pond
• Koi Food: No, koi don’t eat smartweed, but it can attract insects that they will eat.
• Invasive: Proliferates and requires periodic cuttings
• USDA hardiness zones: Smartweed is native throughout the US, thriving in zones 4 to 8.
• How to plant: In a planting bag or wet soil around the pond

10. Cattails (Typha latifolia)

Cattails are a classic pond plant, known for their tall, dramatic appearance. They provide shade, and shelter, and act as natural filters by absorbing excess nutrients and helping maintain the ecological balance of your pond.

• Light: Thrives in full sun and partial shade
• Type: Emergent
• Koi Food: Yes, koi love to snack on its roots.
• Invasive: Yes. You must cut or hand-pull the plants periodically to keep them under control.
• USDA hardiness zone: Thrives in zones 3 to 10
• How to plant: Plant in containers to control its spread.

11. Sweet Flag (Acorus calamus)

Sweet Flag is a grass-like plant with aromatic leaves. It’s perfect for adding texture to your pond and can thrive in a variety of conditions. This plant also helps stabilize pond banks and improve water quality.

• Light: Thrives in full sun to light shade
• Type: Marginal plant
• Koi Food: Koi don’t eat a sweet flag.
• Invasive: No
• USDA hardiness zones: It grows well in hardiness zones 6 to 9.
• How to plant: Use a planting basket and place it on a shelf in your koi pond.

12. Taro (Colocasia esculenta)

Taro has large, tropical leaves that can add a bold statement to your koi pond. While it doesn’t survive freezing temperatures, it’s a great choice for warm climates, where it can thrive in shallow water.

• Light: Grows better in partial sun
• Type: Bog plant, grows in shallow water with its roots buried 4 to 8 inches into the ground.
• Koi Food: Potentially toxic for koi. Plant it on the pond’s edge, where they don’t have access.
• Invasive: No
• USDA hardiness zones: It thrives in zones 8 to 12.
• How to plant: Place under 1 to 6 inches of water in a planting container.

13. Duckweed (Lemna minor)

Duckweed is a tiny, floating plant that offers a lot of benefits. It creates a lush green mat on the surface of the pond, providing shade and reducing the growth of algae. It’s also an excellent food source for koi.

• Light: Thrives in full sun
• Type: Floating plant
• Koi Food: Yes, koi enjoy eating it.
• Invasive: Fast-growing, potentially invasive. Shade from taller plants and water currents from aeration devices slow its growth.
• USDA hardiness zones: Thrives in zones 4 to 10
• How to plant: Just place it in the pond water.

14. Water Lettuce (Pistia stratiotes)

Water lettuce has soft, rosette-shaped leaves that float on the surface of the water. This plant provides excellent shade and helps reduce algae growth by absorbing excess nutrients from the water.

• Light: Thrives in full sun to partial shade
• Type: Floating plant
• Koi food: Yes, koi enjoy water lettuce.
• Invasive: Because it can become quite invasive, it’s prohibited in some states. 
• USDA hardiness zone: Recommended for zones 9 to 11
• How to plant: Place them in the water and let them float.

15. Water Hyacinth (Eichhornia crassipes)

Water hyacinth is a fast-growing floating plant with striking purple flowers. It can provide a beautiful, natural filter for your koi pond, helping to balance the pond’s ecosystem.

• Light: Full sun, but also partial shade
• Type: Floating pond plant
• Koi food: Koi like to nibble at water hyacinths.
• Invasive: Highly invasive – a colony can double its size in 8 days. Prohibited in some states. 
• USDA hardiness zone: It’s hardy in zones 9 to 11.
• How to plant: In planting containers

16. American Waterweed (Elodea canadensis)

American waterweed is an underwater plant that provides essential oxygen for your koi pond. It also helps absorb excess nutrients and prevent algae growth, ensuring your pond stays healthy.

• Light: Thrives in full sun
• Type: Submerged plant
• Koi Food: Yes, koi like to eat elodea plants.
• Invasive: Yes. It is a fast-growing plant prohibited in some states.
• USDA hardiness zone: Thrives in zones 4 to 10
• How to plant: In planting baskets (easier to control) or by adding some weights to the plants and placing them on the bottom gravel layer

Floating Plants (Provide Shade & Nutrient Control)

Floating plants like water lettuce, duckweed, and water hyacinth are excellent for providing shade and controlling nutrients. These plants help to reduce algae growth by absorbing excess nutrients, preventing them from over-fertilizing the water and creating an imbalance.

The Importance of Plants for Oxygenation in Koi Ponds

Plants play a crucial role in oxygenating your koi pond. During the day, plants absorb sunlight and release oxygen into the water, which is vital for your koi’s health. At night, plants stop photosynthesizing and use oxygen, but the oxygen demand is usually lower due to the pond’s balanced ecosystem. Without plants, your pond’s oxygen levels may drop, affecting the well-being of your koi.

Ready to Build a Pond that Supports Both Fish and Foliage?

Creating a koi pond that is both beautiful and functional takes time and careful planning. But with the right plants, you can create an environment where both your koi and the plants thrive. Be sure to choose plants that will not only beautify your pond but also help with water quality and oxygenation, so you and your koi can enjoy a healthy, thriving pond.

Enhancing Pond Health and Balance

Adding the right plants to your koi pond does more than just enhance its beauty. The right plant mix can balance nutrients, provide oxygen, and give your koi a natural environment to thrive in. Keep the pond well-maintained, and your fish will thank you with their vibrant colors and energetic swimming.

Plants Toxic for Koi

While most pond plants are safe for koi, some can be toxic. Always research the specific plants you’re adding to your pond. For instance, certain types of lilies and ivy can be harmful if ingested by koi.

Why Do You Need Plants in Your Koi Pond?

Plants are essential for maintaining a healthy, balanced koi pond. They provide oxygen, reduce excess nutrients, and create a more natural habitat for your fish. Plus, they add beauty and tranquility to your pond, making it a more enjoyable space for you to relax and watch your koi swim.

Enhance Your Koi Pond with Aquaponics!

Looking to take your koi pond to the next level? Consider adding an aquaponics system! Aquaponics combines fish and plant life in a symbiotic system that allows both to thrive. Plants absorb the waste produced by the koi, while the koi benefit from the clean water provided by the plants.