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Bioprospecting for Duckweed

February 25, 2012

Bioprospecting for your green-gold is a fun project.

If you’ve asked around but haven’t sourced your duckweed yet, no worries. Duckweed grows in every region of the planet except for the North and South Pole. Probably even in isolated pockets there.  So, the chances of finding a summer farm pond or city park lake with growing duckweed are darn good.

Here’s the easiest, fastest way to source local duckweed growing sites I’ve found yet. Go on your computer and log on to . Type in your location and begin an aerial search within three miles of your home. Zoom down to a more detailed level in order to see ponds in your area. If a summer view, watch for the two shades of green on different ponds. A pond laden with algae will be a darker green, while ponds with duckweed will be a lighter green.  See link showing two ponds for comparision here.

If you are viewing a satellite view taken in the winter,  watch for ponds with trees overhanging the perimeter of small lakes or ponds. water. These indicate shade and wind protection, two factors in growing duckweed successfully. Also keep an eye open for ponds that are run-off basins from neighboring fields or animal husbandry. These are potential nutrient sources that duckweed thrives on.

Once you have found 3 or 4 potential sites, note the locations and whether they are within a short walking distance of a road. The last thing you want to be doing is carrying heavy samples for a half a mile back to your car.  Then note the closest home to the pond. You’ll be wanting permission to access their pond.

I’ve learned from experience, if you say you are collecting duckweed samples, you’ll end up in a long conversation. Sometimes that’s great, but not if you are in a hurry. Nowadays, I simply say that I’m looking to stock my pond with native water plants and would they mind if I took a small sample?

What’s next? Here’s a short list to insure you are well-prepared both at home and in the field:

  • Have receiving containers ready at home- buckets or a kiddie wading pool filled with rain water or tap water that has sat out overnight to release the chlorine. See post on “Transplanting Duckweed Starters”
  • Items you’ll need to harvest duckweed: heavy duty plastic garbage bags, an ice cooler if temps are over 90 degrees, a swimming pool net on a pole, plastic bucket or two, Optional:  If not bringing an ice cooler, then a plastic bin to hold samples in the car without spilling
  • Personal gear can include: hat, boots, gloves, mosquito and/or tick repellant, sunscreen, bottle of water, and even a camera as this is a fun outing.

Now the hunt begins. Once you’ve gotten permission from the land owner, check out the pond for any floating green plant clusters or masses. Individual duckweed plants run from the size of a large grain of sand for Wolffia to a cluster of “leaves” half the size of your pinkie. They cluster around the stems of cattails and protruding objects from the water. In the spring, you’ll see tiny dots of green on the water surface- new duckweed that is coming out of its hibernation stage. Algae is a usually a darker color and is either so tiny it looks like simply green Kool-Aid or is made of stringy filaments that lay submerged under the water surface.

Use your swimming pool net and gently sweep the surface of the pond, snagging as many clusters of duckweed as you can. Flip upside-down in your plastic bucket and continue collecting until you’ve gotten at least a cupful. My favorite pond will yield a gallon with one sweep of my net. When you’re satisfied with how much you’ve collected, add some pond water to your bucket of duckweed, scraping up some mud from the bottom as you do. Gently pour this slurry into your double garbage bag. This is much easier with someone helping hold the bag.

 Leave an air pocket and knot it shut. Try to keep the contents of each bag to no more than 5-10 pounds. Put the bag back in your bucket and trudge back to your car. Load bags in a styrofoam cooler or plastic tub that won’t tip over for the ride home. Immediately upon returning home, gently release your samples- duckweed, water, mud and all into your waiting containers. Keep in semi-shade for a few days and watch for signs of growth.

Tip: I have had samples die by trying to transplant too many plants in the same container. The duckweed overlapped each other and the ones underneath died. Only transplant enough duckweed to take up half the surface area of your container. The rest can be dried, composted, fed to animals, etc…



2 Comments leave one →
  1. March 4, 2012 12:40 pm

    This is a great blog. I am always looking for more natural and economical feed sources for the chickens. I’ll definitely be trying to get a wading pool started with this stuff. I know many of the local ponds are totally covered in duckweed and no one that I know uses it for anything.
    What about using it as a food source for dairy goats? I would be interested in any information you have on that topic.
    Thanks again for sharing the info!


    • March 5, 2012 7:22 am

      Hi Jeff, thanks for following! Watch for my post today on feeding duckweed to goats. I enjoyed your site and am right there with you on experimenting with hoop houses, et all. It builds such a connection with nature as opposed to buying plastic food from Walmart and sitting in front of a tv because you’ve got nothing better to do. I look forward to what YOU do with duckweed. Would love to do a post on your story this summer. OK?



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