Used Coffee Grounds In Worm Farms – MAY HELP REMOVE PESTICIDE FROM THE SOIL !!

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August 6th, 2017

The Worm Man BLOG

Using Used Coffee Grounds In Worm Farms

(edited to remove the word herbicide and insert pesticide)

Wow – what a title, huh? 😀


For a long time people have been using used/spent coffee grounds in their worm farm.
There’s even been a common abbreviation thought up – UCG.

There was some concern voiced by a few members in the Worm Farming Alliance recently, as to whether VC made from UCG contained the property that coffee is known for- allelopathy.

Allelopathy is the ability to stop other plants growing. So, coffee plants stop other plants taking seed around them.  So it was with great interest that some in the WFA started to research coffee more thoroughly. I mean, if UCG in a worm farm meant you couldn’t then use the VC to grow seedlings – that would be a big deal, right?

Quoc-Huy Nguyen Dinh:

Huy found some great studies, which seemed to indicate that if the UCG was composted, that the allopathic properties disappeared. Lacking any further research to indicate otherwise, it was thought that UCG was safe to use as an input in vermicomposting.

For myself, I just determined to use coffee as PART of my inputs, not a sole input.

Alexandre Rebuffat :

Thanks to Alex for finding this latest gem of a study.

This latest study is by Jorge Dominguez (a BIG name in Vermicomposting research, named on some studies alongside the legendary Dr Clive Edwards) – and Juan C. Sanchez-Hernandez.

The whole study can be found at:

What does this latest study say?

That UCG, when fed to a worm farm, reduces the VOLUME of the waste product; and results in an organic matter that is rich in nutrients, and is enzymatically active; and may help to detoxify pesticide form the soil.

The enzyme bit is interesting to me.

You may know that VC has several enzymes or compounds in it that are plant growth or plant rooting hormones. This is said to be from the slime coat of the worms, and the bacteria in their gut.

The study actually lists these enzymes out.

Detoxifies PESTICIDES In The Soil? SAY WHAT !

But the absolute KILLER part of this study is that it says that VC derived from UCG may be able to DETOXIFY pesticides in the soil !!

To quote the study:

“… in the vermicompost derived from SCGs compared to levels naturally occurring in soils, suggest that this revalorized product has a great potential for the bioremediation of pesticide-contaminated agricultural soils.”


Now, lets not all rush out and spray glypho willy nilly around the garden 😀

But, to me, this means that there is even MORE reason for agricultural producers to use VC products – it may help remove the persistent pesticide that may have gotten into their soil from a careless neighbour, or a previous owner.


Using UCG in the worm farm:

Thanks to my old mate Larry Shier, I trialled using a lot of UCG and aged grass clippings. You may or may not know, I’m also a lawn mowing contractor and get as much grass as I can handle and more . . . except for like now, in the deepest winter – I’m currently just keeping up with what I need, soon I may be mowing the park for the grass 😀

After an extensive trial using the mix in trays, the 3 CFTs and the wedges – I’m certain I’m on a winner here.

I even recently bought a concrete mixer to mix the stuff up, as I am going through so much of the stuff in a week. (I was using a paint mixing bit on an electric drill)



The general mix I use is:

2 gallons water

2 gallons of shredded cardboard

2 gallons UCG

4 gallons well aged grass/leaves

(I don’t worry about exact measurements – the worms don’t mind)

Mix it up with a paint mixer bit on a drill – or a cement mixer 😉



If you follow this mix, be aware that it WILL heat up – so you can’t blanket a small, shallow farm in the mix – you will cook your worms.

The best way is to strip feed smaller farms, or trays, on one side – or “dollop” it around.

In the CFTs I’ve started feeding by making “humps” across the CFT of this mix – leaving a couple of narrow gaps between the humps. I do this to allow for oxygen getting into the bedding – and a place for the worms to retreat from the hot hump a little.

The next feeding, I run the humps the opposite way (if I can remember which way I went last time 😀 )

The worms go APE for this stuff !


So anyway, if you’re a soil geek like me, you’ll probable want to slip on over to researchgate and read the whole study – here’s that link again:

And THANKS to Jorge Dominguez and Juan C. Sanchez-Hernandez (if either of you ever read this, THANKS – you’re an absolute legend!)

For more interesting articles about VC and things to do with soils, see my website:


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