Duckweeds are among the fastest growing higher plants, edible and rich in protein. They grow in lakes that are rich in nutrients, for example from fertilizer runoff. They have been used as tests for water contamination or for the treatment of certain industrial wastewaters. Now, I wonder if one could raise duckweed at home, using wastes or wastewater as fertilizer.

Suitable wastewater sources could be water from dishwashing, compost tea or possibly even urine. Wastes might be kitchen scraps, coffee grounds or the like.

When using waste water, most relevant parameters for contamination can be expected to decrease. Still, I'm right now not focusing on generating clean water but on food production.

While there are some experiences with raising duckweed for feeding fish or turtles, the ones I found all use bought fertilizer or even fish food - no wastes.

I think the following questions should be answered by a success story:

  • when wastewater was used, any special consideration regarding cleaning agents/detergents?
  • when kitchen wastes where used, what kind, what treatment
  • Was there any problem with odour or modges or other pests
  • was there any need for micronutrients
  • It works well as a 'filter' plant for an aquarium, it doesn't need extra fertilizer, uneaten fish food/fish waste seems to be enough, but probably not for rapid growth if you needed it for some purpose.
    – Meep
    Commented Nov 22, 2013 at 19:04

2 Answers 2


Many Aquaponic farmers will grow duckweed to supplement the food they provide to the fish. Since they are interested in the fish waste to feed the plants, the duckweed will not grow fast enough to be the only thing to feed to the fish. I am in the phase of my aquaponics project where we are just getting the Nitrate and Nitrite levels to start to increase. We will soon have fish in the system and duckweed will follow... Best of luck with your research!

  • where do your duckweed get nitrate?
    – mart
    Commented Jul 26, 2013 at 20:32

If you do a little digging, you should find a study of duckweed farming in Vietnam. One of the NGOs looked into it several years ago.

  • 2
    While this information could be useful could you please include some details? (when it was done, authors, results...) Commented Nov 23, 2013 at 11:06

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