Create a Thriving Ecosystem in Your Pond with Aquatic Plants

Aquatic Plants

The growing capacity of your garden does not have to be limited to what can be grown in the soil. Plants that grow in water not only add to the aesthetic appeal, but they also aid the overall functionality of the above ground pond.  Advantages of aquatic plants include:

  • Added beauty 
  • Improved water quality (acts as filter of unwanted substances)
  • Helps eliminate algae production
  • Provides food & shade for fish
  • Prevents water from overheating
  • Reduces overall maintenance

 

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Types of Plants that Grow in Water

The advantage of investing in aquatic plants is that you are able to further enjoy and reap the rewards of your hard work. Keep in mind that 65-80% water surface coverage is ideal. There is an array of different plants that grow in the water and that suit different environments.

  • Floating Plants
  • Marginal Plants
  • Submerged Plants
  • Oxygenating Plants

Floating Plants

Free-floating aquatic plants are an excellent addition to a Growing Dome above-ground pond as they require no soil, instead drawing nutrients directly from the water. These plants help improve water quality by absorbing excess nutrients, reducing algae growth, and providing shade to regulate water temperature. Their roots dangle freely below the surface, offering shelter for fish and other aquatic life while also increasing oxygen levels. Since they do not need to be anchored, they can easily be moved or thinned out as needed to maintain balance in the pond.

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Water Hyacinth (Eichhornia crassipes)

  • Full sun
  • Optimal water temperature: 70-80°F (21-27°C)
  • Minimum temperature: 55°F (13°C)
  • pH range: 6.5-9.5
  • Can be invasive (may be illegal to grow in certain locations)
  • Contain in a floating ring to prevent overpopulation
  • Acts as a biological filter

Water Lettuce (Pistia stratiotes)

  • Full sun
  • Optimal water temperature: 72-86°F (22-27°C)
  • Minimum temperature: 60°F (16°C)
  • pH range: 6.0-7.5
  • Can be invasive (may be illegal to grow in certain locations)
  • Contain in a floating ring to prevent overpopulation
  • May require fertilizer
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Frogbit (Limnobium laevigatum)

  • Moderate sun
  • Optimal water temperature: 68-82°F (20-28°C)
  • Minimum temperature: 15°F (-10°C)
  • pH range: 6.5-7.8
  • Reproduces quickly by sending out runners (can easily take up majority of water surface)

Duckweed (Lemna minor)

  • Full sun
  • Optimal water temperature: 63-79° F (17-26° C)
  • Minimum temperature: 32°F (0°C)
  • pH range: 4.1-8.8 
  • Provides quick and dense surface coverage, but can compete with other plants for nutrients
  • Contain in a floating ring to prevent overpopulation
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Mosquito Fern (Azolla pinnata)

  • Full Sun
  • Optimal water temperature: 63-79° F (17-26° C)
  • Minimum temperature: 32°F (0°C)
  • pH range: 4.5-7
  • Provides quick and dense surface coverage, but can compete with other plants for nutrients
  • Nitrogen fixer
  • Contain in a floating ring to prevent overpopulation

Mosquito Fern and Duckweed are types of highly invasive floaters. Once they are part of the pond ecosystem, they are very difficult to get rid of. They tend to quickly take over the water surface and may end up competing with other plants for essential nutrients. When these floaters start to take over, they can be added to a compost pile or act as food for chickens.

Submerged/Emergent Plants

These water-loving plants need to be potted in containers with a heavy aquatic soil mix and placed below the water’s surface. To ensure they remain at the correct depth, they require stands to support them at the optimal height. In smaller Growing Domes, flowering may be limited, but their unique leaf structures provide excellent surface coverage, adding texture and visual interest to the pond. When selecting stands, avoid cement blocks or any materials that could alter the pond’s pH balance or risk puncturing the liner.

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Sacred Lotus (Nelumbo nucifera)

  • Full sun
  • Optimal water temperature: 75-87°F (24-32°C)
  • Minimum temperature: 32°F (0°C)
  • pH range:
  • Plant in a pot at least 12” deep and 24” wide
  • Pot must be submerged. Taller lotus can handle deeper water (up to 18”), while dwarf varieties prefer shallower water (2-12”)

Water Lily (Nymphaeaceae)

  • Full sun
  • Optimal water temperature: 60°F-75°F (16-24°C)
  • Minimum temperature*: 32°F (0°C)
  • pH range:
  • Bloom Spring – Fall
  • Plant in a pot at least 10” deep and 12”-20” wide
  • Pot must be submerged. Lower the plant to its final depth of 12-16”. 
  • *Hardy water lilies are more tolerant of cold and can be left in the pond as long as it does not freeze. Tropical water lilies will die if water temperatures drop below 60°F, therefore rhizomes have to be taken out of the water in winter.
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Parrot Feather (Myriophyllum aquaticum)

  • Full sun
  • Optimal water temperature: 70-100° F (21-38° C)
  • Minimum temperature: 32°F (0°C)
  • pH range: 6.8-8.0
  • Can be grown as an emergent plant or floating plant
  • Contain in a floating ring to prevent overpopulation
  • Generally does well with no fertilization

Marginal Plants aka Bog Plants

Marginal plants typically grow in the shallow water or consistently moist soil around a pond’s edge. In a Growing Dome above-ground pond, these plants are placed in floating planters filled with aquatic planting medium or a specialized aquatic soil blend. These plants provide natural filtration and also create opportunities to grow unique edible plants that thrive in wet conditions. By incorporating marginal plants, you can introduce diverse textures, colors, and varieties that wouldn’t typically be possible in a standard greenhouse environment, enriching both the aesthetics and functionality of your Growing Dome.

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Umbrella Palm (Cyperus alternifolius)

  • Full sun to partial shade
  • Optimal water temperature: 60-80°F (15-27°C)
  • Minimum temperature: 40°F (5°C)
  • pH range: 6.0 – 7.5
  • Thrives in high humidity environments (50% or more)
  • Can grow up to 6’ tall
  • Roots need trimming occasionally
  • No dirt or planting medium needed

Taro (Colocasia esculenta)

  • Partial shade
  • Optimal water temperature: 77-95°F (25-35°C)
  • Minimum temperature: 32°F (0°C)
  • pH range: 5.5 – 6.5
  • Edible when cooked
  • May attract whiteflies. If an infestation occurs, take the plant outside and cut the entire stem off and dispose of it. Don’t worry it will grow a new one!
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Water Celery (Oenanthe javanica)

  • Full sun to partial shade
  • Optimal water temperature: 65-80°F (18-27°C)
  • Minimum temperature: 5°F (-15°C)
  • pH range: 6.5 – 7.5
  • Aquatic-terrestrial plant so keep roots submerged in water and mist the leaves daily

Bloody Dock (Rumex sanguineus)

  • Full sun to partial shade
  • Optimal water temperature: 65-80°F (18-27°C)
  • Minimum temperature: 15°F (-9°C)
  • pH range: 5.5 – 6.5
  • Edible raw or cooked
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Watercress (Nasturtium officinale)

  • Partial shade
  • Optimal water temperature: 50-75°F (10-24°C)
  • Minimum temperature: 32°F (0°C)
  • pH range: 6.5 – 7.5 
  • Edible raw
  • Thrives in moving water

Mexican Butterfly Flower 

  • Full Sun
  • Optimal water temperature: 65-80°F (18-27°C)
  • Minimum temperature: 50°F (10°C)
  • pH range: 6.0 – 7.0
  • Can grow 2-3’ tall
  • Flowers are vibrant yellow and orange hues
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Oxygenating Plants

These plants that grow in water provide oxygen for your pond.  They should sit at least 24″ under the water’s surface to provide oxygen to the lower water regions of our ponds.  The primary oxygenators include anacharis, hornwort, and foxtail. The preferred technique in our ponds would be to suspend them inside a mesh bag (with a smooth rock added to keep the mesh bag hanging low in the water).

Algae Prevention

If you find you have an excess of algae in the pond, here are some possible reasons:

  1. You have too many fish. Koi need 200 gallons of water per fish to reach 6-8”. Goldfish need 100 gallons/fish.
  2. Not enough coverage on the pond surface, which should have 65-80% coverage from floating plants or shade.
  3. Not enough aeration, especially in the lower half of the pond.
  4. You are overfeeding your fish (They should use a “spring-fall” lower-protein feed between 50 & 60 degrees). Only feed every 3-4 days, what your fish can eat in 5 minutes.
  5. Stop feeding your fish once the pond drops below 50 degrees, this allows them to go into their winter slowdown without food on their bellies. Full bellies could harm or kill your fish.
  6. All browning water plant debris should be removed. This includes trimming off segments of water hyacinths and other plants that are not cold tolerant. This also includes pruning back most permanent water plants in December to a 6” height.
  7. Do not fertilize water plants during Nov, Dec, & Jan. This is also their quiet time!
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Common Fish for the Pond

Floating plants in the pond rely on the fish for their nutrients. Goldfish and Koi are the most common types of fish raised in the Growing Dome pond. Local pet stores or fisheries are the best place to get freshwater fish, but they may also be purchased online and shipped to your door overnight.

We recommend waiting a few weeks after adding your water plants before introducing fish into your pond. This lets the environment adjust and be more stable for your fish. It is also important to treat tap water and test well water before adding fish to your pond. Water softeners are not recommended for your above ground pond because they replace electrolytes necessary for your fish (calcium and magnesium) with sodium, resulting in death of the fish.

Edible Fish

Edible fish can also be harvested in the Growing Dome, whether you have aquaponics in your greenhouse or not. Tilapia is probably the most common and will require more oxygenation than goldfish. You must also keep your pond above 50°F or they may die, but they will add a sustainable source of protein to your diet while also giving your plants additional nutrients!  Please do your own research on food safety when consuming fish from your Growing Dome. Other edible fish varieties include Yellow Perch, Bluegill, Catfish, and Bass.

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