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Overwintering Duckweed

September 20, 2013
Turions and mother fronds of Spirodela polyrrhiza  Photograph courtesy of Prof. Cheryl C. Smart

Turions and mother fronds of Spirodela polyrrhiza from “The Charms of Duckweed” by Dr. John Cross Photograph courtesy of Prof. Cheryl C. Smart

Do you hate to see your duckweed freeze and die every late fall?  If you are like me, you’ll be glad to know that while the bulk of it WILL die as your ponds freeze over, some of your duckweed has gone into hibernation mode and will return in the spring. Here is how:

Duckweed forms specialized small fronds called turions in the autumn. These turions are composed of starch to roughly 70% of its body weight instead of the normal 15-40%.  Starch is heavier than water so this allows the turions to sink. Depending on the species, some only sink a few inches below the water surface while others sink down into the mud where they wait patiently for spring. Then they begin photosynthesis and form little air pockets which makes them boyant. They rise back up to the water surface and begin growing out normal daughter fronds.

You might assume like I did that the formation of turions was temperature-related. Actually, it has to do with the amount of phosphate in the water column. Dr. Klaus Appenroth of Jena, Germany has been studying turion formation for over a decade and discovered this in his research.

So what does that mean for our in-ground duckweed ponds and above ground kiddie pools?  If you are in the frigid north, ensure you have a deep enough ponds that will allow mud to remain unfrozen during the winter. Kiddie pools may not be deep enough. You can always bring in a container of duckweed water and put it in a cool southern window. Or you can let Nature take its course. If your kiddie pools of duckweed totally freeze, source a new batch in the spring from nearby wild ponds.

A little batch of duckweed in a glass bowl on your windowsill looks amazing against the backdrop of a January snow fall.

6 Comments leave one →
  1. Robert Estes permalink
    October 7, 2022 2:17 pm

    I raise endangered species ducks in the Texas Panhandle where winter temps may drop to zero for several days at a time. I was told that duckweed can be harvested and spread on a horizontal window screen to dry, then packaged in plastic bags. The following Spring they can be reintroduced to the pond to restart Duckweed growth. Is that true, or must some of the Duckweed be kept indoors in an aquarium or bowl during winter months? Thank you,
    Robert Estes,


    • October 7, 2022 3:36 pm

      You could keep some growing indoors just as precaution but generally if duckweed has been growing year after year in your pond, the chances are it is the type of species that produce starchy bodies called turions that sink to the mud in the fall and regenerate every spring. As long as your pond is deep enough and mud does not freeze solid, your duckweed will come back. Dried duckweed cannot be brought back to life.


  2. Sheri Robson permalink
    January 3, 2021 5:37 pm

    Thanks for the info on being able to put duckweed in a glass bowl on a windowsill. Very helpful 😊❤


  3. September 30, 2013 4:57 pm

    Hi Sue, Less phosphate induces turion formation.


  4. Susan Munroe permalink
    September 29, 2013 1:06 pm

    Re: the phosphate… does that mean more or less phosphate/phosphorus? Should I add some chicken poop to the containers to add more, or hold off?


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