Pond Plants and The Pond Ecosystem: A Quick Reference Guide for Pond Owners

Pond Plants and The Pond Ecosystem: A Quick Reference Guide for Pond Owners


A pond’s ecosystem is the balance between fish, plants, bacteria, critters and other living organisms. Within this ecosystem, the nitrogen cycle is occurring.


Plant waste, fish waste, uneaten food, etc. break down in a “sequence of biochemical reactions." One of the primary bi-products is ammonia (toxic to fish at approximately 0.02 ppm). Nitrosomonas bacteria help to break down ammonia into nitrites (toxic to fish at approximately 0.1 ppm). Other bacteria then break down nitrites into nitrates (toxic to fish at approximately 50 ppm). 

Plants consume all 3 of these forms of nitrogen - ammonia, nitrites and nitrates. However, many studies are indicating that many aquatic plants prefer ammonia, which helps to further protect our pond fish. 


Problems within your pond occur when the ecosystem becomes out of balance. Too many fish, or over feeding the fish, produces too much fish waste - which is primarily ammonia. Too much dead plant material can deplete oxygen supplies during decomposition. Too small of a filtration system, or too little of the correct bacteria, can cause ammonia to build up. The trick is to keep the ecosystem in balance. 


In an ecosystem, everything is relative. If we add more fish, we might need to add more bacteria, a bigger biological filter or more plants. As fish grow and multiply, will the “filtering system” handle it? It did yesterday, but will it be adequate tomorrow? It will, only if we maintain the balance within our ecosystem. Nature will continue to try to maintain this balance if we allow it to do so. Guidelines to keep in mind for your pond's health include: 

1.) Up to 1 inch of pond fish per square foot (s.f.) of water surface area (s.a.) or per 5 gallons of water, in the first year. Half as many if your pond fish are koi. Remember, fish will grow and multiply in water gardens! 

2.) Floating pond plants (water lettuce or hyacinth): one per 10-15 square foot of surface area. 

3.) Submerged pond plants (hornwort): one bunch/plant per 2 square feet of surface area. 

4.) Marginal pond plants: enough to plant approximately 25% of the perimeter of the pond as a guideline.  

5.) 40-60% of the pond’s surface should be shaded by lily pads or by other aquatic plants. 

6.) Having adequate mechanical and biological pond filtration, with correct water flow through these systems, is necessary. 

7.) Gallons in a Pond: L' x W' x D' x 7.5 


Hornwort (Ceratophyllum demerusum) 

  • Needs Sun to part shade 
  • Height: Up to 10’ 
  • Lives in Hardy zones: 4-11 
  • Water Depth: 1-10’ 

Hornwort is a non-rooting oxygenating plant with leaves packed tight in whorls that form plumes at the end. It helps in preventing “pea soup” green water. 


These pond plants are sensitive to the cold and like water temps 65° and warmer. 

Water Hyacinth (Eichornia crassipes) 

  • Sun lover 
  • Height: 4"-16” 
  • Tolerates Shade 
  • Hardy Zones: 9-11 

Water Hyacinths float on the water surface and have beautiful purple blossoms born above air-filled, waxy green leaves. Its roots hang below, providing shelter for fish and absorbing excess nutrients in your pond water. 

Water Lettuce (Pistia stratiotes) 

  • Sun lover 
  • Tolerates Shade 
  • Hardy Zones: 9-11 

Water Lettuce floats on the water's surface and has velvety pale, blue-green leaves. Its roots hang below, providing shelter for fish and absorbing excess nutrients in your pond water - thus promoting clean, clear water. 

For more knowledge and understanding on the wonderful and beautiful world of pond plants and their fascinating ecosystem, please view Aquascape’s Video on a Pond's Eco-System here

Visit Hoffman's Water X Scapes' Pond Plants section online to see our spectacular selection of pond plants - from lilies and irises to lotuses, ferns and many more breathtaking varieties. 

Lastly, please do not hesitate to contact Water X Scapes with your own questions or issues regarding hardy pond plants, pond health, and pond maintenance and design services. We're here for you!