Significance

• Fertilizing freshwater plants in ponds can drastically increase fish production and is often used in fishing ponds to increase harvests. Fertilizing pond plants creates an increase in microscopic algae production, which provides more food for small fish, thus enhancing the pond's food chain. A fertilized pond can produce up to three times as many fish as an unfertilized pond. Fertilizing can also help reduce problems with aquatic weeds.
  
  

Considerations

• Some freshwater ponds need no fertilization. Ponds with low pH, muddy or cloudy water do not need fertilization. Applying fertilizer to a weedy freshwater pond will only make the weed problem worse so aquatic weeds must be controlled before fertilizing. Pond owners who feed fish with prepared food should not fertilize as the excess nutrients released by fish work as fertilizers. Because fertilizing can cause increased fish production, if the pond is not used for heavy fishing fertilizer may not be desirable.
  
  

Timing

• The best time to fertilize is in the spring once the freshwater pond's temperature reaches 60 degrees Fahrenheit. Most ponds should be fertilized three times per year during spring, summer and fall. Fertilizing in cold weather can cause algae problems and should not be attempted. Testing the pond's water is crucial in determining when more fertilizer is needed.
  
  

Preparation

• Some preparation is required before adding fertilizer. The pond's alkalinity and water hardness should be at 20 milligrams per liter or parts per million. If you have soft water, a lime application may be necessary four to six weeks before applying fertilizer. Have your pond's mud analyzed through a local natural resources agency or extension program to see if this is necessary.
  
  

Types of Fertilizer

• Inorganic fertilizers should be used in freshwater ponds. Organic fertilizers can lead to problems with water quality and excessive algae and kill fish. There are solid and liquid fertilizers. Solid formulations in tablet or granular form are dissolved in the water and should not make contact with the bottom of the pond as the nutrients will stick there. Liquid fertilizers applied to the pond work more quickly than solid fertilizers as they are already dissolved but generally do not last as long.
  
  

Applying Fertilizer

• All fertilizers should be applied as the label instructs. Solid fertilizer can be released into a freshwater pond by placing it on a fertilizer platform suspended in the pond at a depth of 1½ to 2 feet. Fertilizer bags can also be placed on the bottom, opened on the top and staked in shallow water. Tablet fertilizer pressed into the pond's soil is another option. Liquid fertilizers must be diluted before being applied to the pond.
  
  

Safety

• Special care should be taken when applying fertilizers as they are made of caustic chemicals. Wear protective eyewear, gloves and clothing. Fertilizers will corrode metal, so metal equipment must be cleaned after contact with fertilizer. Follow the product instructions carefully to ensure the safety and health of your pond.