Do Worms Like Beer?

I must admit to feeling pretty apprehensive when I saw the subject of this email (same as the title of this post) from one of our readers! I had visions of beer being poured directly into a worm bin (which might sound like fun to some, but certainly wouldn’t be great for the worms!)
As it turns out, it is a query about brewery wastes – one of those tricky materials that – while certainly offering plenty of “food” potential – warrants a very cautious approach.

I had read somewhere that worms like beer , so I took a trip to the closest micro-brewery and after a couple of taster sets , decided my red worms might like a couple of pounds of spent malt . I mixed it in
with the other compost and 5 pounds of red worms , much to my surprise they didn’t seem to like the excessive heat the malt was throwing off (still fermenting?) and seem to have all perished! Please advise your readers to “not try this at home” as the “brewery worms” seen on TV , don’t seem like home brewers!!!
I have now resorted to having to lie to my wife as to the current condition of OUR worms ! Do you have any advise on what I should tell my wife ?

Warmest Regards

Hi Haven,
Hopefully your wife isn’t one of our regular readers! I couldn’t resist adding this as one of our “Reader Questions” posts since it is a topic that deserves some attention!

I myself have not used brewery waste in a worm composting system for quite a few years now, but when I DID experiment with it, I had a VERY challenging time getting it to work well as a “food” material. Like many others, I’d read that it was supposed to be a fantastic material for vermicomposting. Edwards and Bohlen (1996), in fact, offer this glowing review on page 247 of “Biology and Ecology of Earthworms”:

[Brewery waste] needs no modification in terms of moisture content to grow earthworms. Worms can process it very quickly and grow and multiply rapidly in it.

This is not even close to what I experienced with this material. I found that it had the tendency to become very foul very quickly, and as such, was not well received by the worms even in relatively modest quantities and/or when mixed with other materials.

Looking back now, with quite a bit more experience under my belt, I can certainly see why this may have been the case. It is something akin to adding material straight from a bokashi bucket into a worm bin – something you can get away with in moderation (and when using a larger, well-ventilated system), but a bit trickier with smaller enclosed bins. In both cases, you are dealing with a material that is very anaerobic and which has undergone some fermentation. Well, we all know what fermentation can produce – alcohol! Not exactly something you want to be adding to your worm composting ecosystem!

I’m guessing there must be different kinds of brewery wastes. I just can’t see how else Dr. Edwards (mentioned above – who was involved in the original research being referred to in the book) could have reached that conclusion otherwise! In my experience (and clearly, the experience of others) this material definitely DOES require some “modification” prior to use!

What I would likely recommend now is some sort of “pre-composting” (or at least “aging”) period before attempting to use the material in a vermicomposting system. Some may recall how long it took for Red Worms to colonize that “bad” bokashi waste I dumped out in my yard this summer (see “Bokashi Gone Bad” and “Bad Bokashi Update“). Clearly, even when excess moisture is allowed to drain, and the material is allowed to sit exposed to the elements, it can take quite some time for aerobic decomposition processes to become re-established.

If one had a compost tumbler and lots of dry absorbent material (such as coco coir), plus some mature compost, I suspect you could speed up the process considerably! In terms of knowing when the material is “ready”, my recommendation is simply to go with a good ol’ smell test (this applies to any material you are planning to add to a worm composting system for that matter). Some stink should be fine (and again, in larger open systems you can get away with a LOT more than in a small enclosed bin), but if the material still smells really foul when you dig into it, it likely isn’t yet ready to be used as worm food.

Unfortunately, my talents as a marriage counselor aren’t exactly on par with my vermicomposting know-how, so I’m not really sure what to recommend you tell your wife, Haven! (haha)
If I was in your shoes, I’d likely use the quote from Edwards and Bohlen (highly reputable worm experts) as a starting place from which to build my case! You didn’t even put the worms in pure brewery wastes, as they seem to be suggesting! It was a perfectly honest mistake the way I see it.

Smoothing things over with a new batch of worms probably wouldn’t hurt either!


Edwards, C.A. and P.J. Bohlen. 1996. The biology and ecology of earthworms (3rd Edition). Chapman & Hall, London, 426pp.

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    • Anna
    • August 16, 2010

    I’ve had good luck with brewery waste in my outside worm trench. I add the grains and the cheesecloth bag that contains them to the trench and have later seen the worms happily crawling around inside. These grains have been boiled but have not been fermented. To be fair though, I pre-composted these bags of grain and set them off to the side of the trench so the worms could avoid them if they wished.

    I’d also like to add that I would feel much better hearing about the untimely death of my worm herd if I were simultaneously presented with a new worm herd.

    • LARRY D.
    • August 17, 2010

    Any time you mess with grains,you are living on the edge.I use corn to drive the heat of my horse manure hot composter up.I’ve heard bad things involving spent brewery product.
    One i had though involved plain old white rice.Luckily my bin is big.
    I dumped a pot of rice in and partially buried it.Three days later i went out at dark for one last check, and saw steam rising from within.It got so hot,it had cooked a banana skin brittle.if you would stick your hand in it,you would be going to the hospital.
    It dried a one foot circle in the vc around it.Needless to say,the worms headed for dodge.
    So be careful with the grains.I only wish i would have took a temp.But that was the last thing on my mind!

    • John Duffy
    • August 17, 2010

    I would agree with Anna. Present you wife with some new worms (after a few beers)

    • Erika
    • August 17, 2010

    I am a lucky enough gal that my husband doesn’t mind me having the Worm Inn set up in our kitchen. I would have to agree you might be best off letting your wife know while giving her another 5 pounds of worms as a peace offering.
    If the heat is to high with the brewery waste I am sure this wouldn’t work, but I wonder what would happen if just worm eggs were used in a bin with the brewery waste and they were born into it?

    • LARRY D.
    • August 17, 2010

    And roses!(live ones of course!)

    • Bentley
    • August 17, 2010

    ANNA – Thanks for sharing that. I’ve been hoping to find someone who has used them successfully. If I had some available to me now I’d definitely be using them in my outdoor trenches too – much more forgiving than a plastic tub, and like you said, the worms can stay away until the material is “ready” for them.
    LARRY – I’ve had a similar a experience with rice (back when I was a bit wet behind the ears), and think you are on target with grains. I suspect there are a few factors at work here. On the aerobic front (where the most heat is generated), I suspect that the readily available source of carbs in the grains ends up being like a big ol’ reserve of rocket fuel for microbes. As everything heats up oxygen gets used up more quickly, and these starchy wastes tend not to be great for air flow, so things shift to anaerobic mode. Again, due to the readily available carbs, fermentation tends to proceed from there, and our worms end up drunk!
    That’s my theory and I’m stickin to it!
    ERIKA – Your idea is actually quite good. I think as long as the temperatures didn’t get TOO high around the outer edges, and as long as the heap of brewery waste had reasonably good air flow, I think those cocoons would eventually hatch out (when the time was right) and the hatchlings would be even more well suited for life in this material than any adults you attempted to introduce (there have actually been academic studies that have shown this to typically be the case).

    • Anna
    • August 17, 2010

    Bentley–I should also add that I was adding a relatively small amount of spent grain. It was a bag roughly the size of a medium canteloupe and had been in my regular compost heap for at least 5 months before I added it to the trench. I also know that Will Allen uses spent grains. I’m not sure how he does it, but I know that when I got my first set of worms (from Growing Power), they came in a bedding with plenty of brewery grains mixed in. I have an acquaintance who used to work there…perhaps I’ll track her down and ask her.

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