how to grow duckweed indoors

How to Grow Duckweed Indoors

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Duckweed (Lemna spp.) is among the world’s smallest plants. In fact, the Wolfia genera of duckweed has the world’s smallest blossom — each flower is no larger than a candy sprinkle, according to the Library of Congress. In nature, duckweed floats in carpets on quiet waters where it provides protection to aquatic creatures. Duckweed is also used in aquaculture. At home, duckweed can be grown in a large aquarium near a sunny window. Winter-hardy in U.S. Department of Agriculture plant hardiness zones 4 through 10, these tiny plants are forgiving of temperature variations, making them easy to grow indoors. Ducks, turtles, carp and koi eat duckweed, whether it’s growing in the pond outside or specially grown indoors just for their enjoyment.

Cover the outside of the aquarium with black contact paper. While in ponds, duckweed will outgrow algae, in an aquarium the algae will thrive in the light coming in through the glass.

Place the aquarium in a warm, sunny location where it receives at least six hours of sunlight daily.

Install an airstone and small pump to keep the water oxygenated. Set the pump at its lowest speed.

Fill the aquarium with pond water if possible. Otherwise, use tap water but allow the water to stand overnight so the chlorine evaporates.

Add a balanced 10-10-10 liquid fertilizer that contains iron, diluted with four to five times the normal amount of water. If you are also stocking your aquarium with fish, don’t add any fertilizer.

Test the water pH with a pool strip. The ideal pH for duckweed is between 6.0 and 8.0. If the water pH is too high or low, alkaline and acid buffers are available at aquarium supply stores.

Add the duckweed to the aquarium. Handle the plants gently; they are easily damaged.

  • Bioponica: Tips for Growing Duckweed
  • Fairfax County Public Schools: Study of Northern Virginia Ecology — Common Duckweed
  • Missouri Botanical Garden: Tips for Growing Duckweed
  • Missouri Botanical Garden: Lemna Minor
  • Aquasol: Facing the Economic Reality of Sustainable Commercial Aquaculture
  • Library of Congress — Everyday Mysteries: World’s Smallest Flower
  • Hang a fluorescent shop light over the aquarium if there isn’t enough sunlight; duckweed requires at least six hours daily of direct sunlight.
  • Scoop the duckweed out of the tank with a small net to feed it to your turtles or fish.
  • Keep children and pets away from open top aquariums. A child can drown in as little as 1 inch of water.
  • Keep all fertilizers and chemicals out of reach of children and pets.
  • Never pour water containing duckweed into storm drains or wetlands; it could be invasive in your area.

With degrees in fine and commercial art and Spanish, Ruth de Jauregui is an old-school graphic artist, book designer and published author. De Jauregui authored 50 Fabulous Tomatoes for Your Garden, available as an ebook. She enthusiastically pursues creative and community interests, including gardening, home improvement and social issues.

How to Grow Duckweed Indoors. Duckweed (Lemna spp.) is among the world’s smallest plants. In fact, the Wolfia genera of duckweed has the world’s smallest blossom — each flower is no larger than a candy sprinkle, according to the Library of Congress. In nature, duckweed floats in carpets on quiet waters where …

What Is Duckweed: How To Grow Duckweed In An Aquarium Or Pond

Those who keep fish, whether in an aquarium or a backyard pond, know the importance of keeping the water clean, minimizing algae, and feeding fish well. A tiny, floating plant called common duckweed (Lemna minor) can do all that and more.

While considered a nuisance in some places, its positive attributes can outweigh the negative, and many who keep fish want to learn more about it and how to grow duckweed in ponds or aquariums.

What is Duckweed?

Found virtually all over the world in aquatic environments, duckweed is one of the smallest flowering plants, measuring 1/16 to 1/8 of an inch (.159 to .318 cm.) long. It has one to three light green leaves with a flat, oval shape. It thrives in stagnant water, floating in dense colonies.

Its rapid reproduction by division can be either a boon or a bust. As fish food, the quick growth provides an economical and nutritious food source. It absorbs harmful nitrates and other chemicals from the water, thereby improving water quality and because of its spreading canopy, reduces the light that fuels algae.

However, if left unchecked, duckweed’s growth can quickly overtake a pond, depriving oxygen to fish and sunlight to lower aquatic plants.

Growing Duckweed in Aquariums

Growing duckweed in aquariums is easy. It is not a fussy plant to grow and derives most of its nourishment from the air. Duckweed is favored by goldfish, tilapia, koi fish, and other fish varieties and provides a nutritious and protein packed food source.

To grow duckweed in an aquarium, it often can be purchased in a pet store. Duckweed will tolerate low to high light, and soft or hard water. Temperature should range from 63 to 79 degrees F. (17-26 C.). For a denser growth provide a high quality, full spectrum light and add trace minerals during water changes. Make certain the aquarium water is calm with no current, or the rapid growth will diminish.

Duckweed also can be cultivated separately or in a tank with non-herbivore fish. To grow it separately, use a rectangular container at least 5 inches deep, 18 inches long, and 12 inches wide (13 x 46 x 30 cm.) with dechlorinated water, aquatic plant fertilizer, a drinking straw, pH meter, thermometer, and small net.

Clean the tank without chemicals or soap, then add water. If treated tap water is used, add the plant fertilizer. Using the drinking straw, blow air into the water about every 10 minutes until the water is oxygenated. Alternatively, a water oxygenator can be used.

Check the pH level. It should be between 6 and 7.5. Add duckweed. To harvest, scoop the duckweed with the fish net or a coffee filter and transfer to fish tank for food.

Growing Duckweed in Ponds

In garden ponds it is important to monitor the growth of the duckweed to prevent complete coverage of the pond, which results in oxygen depletion and fish kill. Excess duckweed can be raked or skimmed off the top of the pond.

A handful of duckweed purchased from the pet store should be adequate to start the plant growing in your garden pond.

Many who keep fish want to learn more about duckweed and how to grow it in ponds or aquariums. Click this article for more information.