Duckweed floating on a freshwater pond
image by Klein Kroos
Duckweed, botanically known as lemna, is a tiny pale green aquatic plant that floats atop fresh water lakes, ponds and pools. Duckweed throws seeds and has between one and three petals on each plant that grow up to an 1/8 inch in length each. Every petal grouping has a thin root string that hangs down into the water. Ducks love to eat Duckweed and can spread it as they move amongst bodies of water.
Acquire healthy Duckweed plants from a reputable aqua garden supplier either online or at a local bricks and mortar storefront. They come in plastic bags or plastic cups with hundreds or thousands of individual plants per package. Because it is a fast colonizer, just a couple packages can establish themselves in a medium size pond in a few months.
Tip the bag or container gently onto the surface of the water, allowing the Duckweed to flow out and begin to float on the surface. Most plants will right themselves orienting their root side down. Use your fingers to flip over the few plants that do not right themselves.
Allow the Duckweed to float on the surface of the water where it will naturally form into colonies. No fertilizer is required as it lives on the nutrients in the water supply. Duckweed thrives in full and partial sun.
Keep the Duckweed population in check to prevent de-oxygenation and threats to the body of water's ecosystem and to fish and other aquatic animals. Skim portions of the surface periodically to lift the duckweed out and discard it.