Aquatic plants are must-haves for gardeners lucky enough to have their own ponds. They lend elegance and beauty to the water's surface and help keep pond water clean by filtering it with their roots. But most aquatic plants, especially floating ones, reproduce quite rapidly and must be periodically removed to keep the water healthy for fish. Luckily, aquatic plants are the perfect addition to the compost pile. Their high moisture content speeds the compost process and their mineral-rich tissues provide excellent nutrition for other plants. Composting aquatic plants is easy and relatively quick.
Spread a tarp on the ground near the edge of your pond. Collect floating aquatic plants from the surface of the pond with a pool-skimming net and pile them on top of the tarp. Harvest long-stranded algae by gently detaching it from rocks or other surfaces with your hands. Shear pond grasses down to 6 inches using old scissors, being careful not to disturb their roots.
Allow the excess water to drain off, and then spread the plants out on the tarp so that they make a layer about 4 to 6 inches deep.
Use the machete to coarsely chop the aquatic plants into pieces about 2 inches long. Omit this step if you are using tiny plants, like duckweed or fine algae.
Place a 6-inch-deep layer of lawn clippings or other fine green waste at the bottom of a compost ring. Add a 4-inch-deep layer of the chopped aquatic plants while they are still moist. Place a 6-inch layer of shredded newspaper over the plants. Cover this with a 2-inch-deep layer of fresh chicken manure. Add more layers, repeating this pattern, until you have used all the aquatic plants.
Cover the compost ring with an old tarp to retain heat and moisture. Check the temperature and moisture level of the composting materials periodically. The pile should feel warm and moist.
Remove the tarp after one to two months. The pile should be significantly smaller, drier and cool. Replace the tarp and wait another few weeks if the pile is still warm.
Work the finished compost through a ¼-inch wire screen before adding it to the garden, so that the nutrients can be easily taken up by plants.