What Things Can’t You Feed To Worms And Why?

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June 30th, 2017

The Worm Man BLOG

What Things CAN You Feed To Worms – And What Things Can’t You Feed To Worms?

I’ve supplied a list of things to avoid at the end of the commentary. Until you understand your worm farm and what these foods will do to it, it’s best to leave them out.


Generally speaking, worms are able to eat most things that were once alive.


If something is not on this list, it is usually fine to feed to your worms – paying attention to not over feeding.
You can read up on “How to feed a worm farm using the pocket feeding system” which includes a guide on how MUCH to feed here on my blog:


This next part is the most IMPORTANT THING you’ll read on this subject:

In the right circumstances and conditions – and in the right relative volumes.


What do I mean by that?

Relative volumes means too much of a bad thing in too small of a worm farm. Or it could be turned around to say if it’s only a small bit of something on the avoid list in large enough of a farm it will do little to no harm.

Circumstances and conditions is about how BIG (or small) your worm farm is – and the ability of the worms to escape a problem material until it becomes more edible for them.

Some things are just smelly and yucky in a small bin – but would be ok in a larger in-the-ground worm farm.


The best way to illustrate this is with some examples:


I know of a plant overseas using worms to dispose of the leftover bits from a chicken processing plant.

Would I advise you to chuck a chicken carcass into your small enclosed worm bin? NO !



If I am making a sandwich and cut off the 2 ends of the tomato that I don’t eat – I throw that into my worm scraps bucket.
Would I advise throwing a whole BUCKET full of tomatoes into a small enclosed bin? NO !



Sometimes when I have a full (about 1 gallon) bucket of worm scraps I will throw some onion peelings in there. (Relative volumes). As my farms are quite large and outdoors, this doesnt make a problem for me.
Would I encourage you to throw a whole bag full of onions in an enclosed bin? NO !



Well, this one ALWAYS is a contentious issue.
I believe people who have success with it may be only placing the skins and ends in the worm bin – and perhaps have a large bin.
If they have a large bin, how can they tell if they have killed a few worms by doing it?
Maybe the large bin enabled the worms to escape the problem.
If you have a small enclosed bin, like a plastic box or WF360 etc – I think you should err on the side of caution.


Sometimes, though, risk outweighs reward with things like this.
“If in doubt, leave it out” – and feed something safe – and place the questionable stuff in a compost heap or throw it out.


Here’s the list of things to avoid and why:

This list is contentious; people have many different ideas.
Some people, who are more experienced, will tell people to put all this in, but not offer the needed advice on cautions or relative amounts.


Salt is generally avoided as it will burn the worms’ skin.

But it goes to relative amounts too.

Example: Putting a pinch of salt into a pot of coffee and then using the coffee grounds in the worm bin will be fine.
I imagine the coffee as only being a small part of your food input.
I’m definitely NOT saying to put everything salty in the bin.

Example: Putting the cobs of corn in the bin after you eat them – and youve put butter and salt on the corn.

You’e eaten most of the corn – I would just rinse the cobs under some tap water and put them in as-is.

Use caution with salt.



– it smells as it breaks down

– it creates heat

– it draws vermin like rodents to the area of the worm bin (and YES – rodents WILL eat worms).

– rodents in turn will draw snakes into an area.


Onions, garlic and others of the allium family:

– are acidic (yes, buffers help with this but why waste buffers?)

– smell ABSOLUTELY terrible when breaking down

– worms will eat them after a time in the farm



– are acidic (yes, buffers help with this but why waste buffers?)

– seeds seem to survive well and become volunteers in your garden

– worms will eat them eventually



– is acidic

– contains limonene which inhibits it’s breakdown and is toxic to worms, but is broken down in time

– worms will eventually eat it once it starts to break down


Pineapple & Papaya (Pawpaw)

– is acidic

– contains meat tenderising enzymes that may kill worms (Someone told me they fed a whole pineapple before going on holidays and returned to find all their worms slimy and dead)


Grease And Oils

– as worms breathe through their skin, excessive oils could prevent this happening.

– natural oils are fine – for example in avocado

– a SMALL amount of oil on a salad dressing may be fine

– I use canola oil to oil my shredder blades. I then feed the cardboard to the worms without pause. Remember relative volumes – a teaspoon of oil in 100 gallons of bedding won’t cause issues.



Pet Manures:

It’s generally considered to be a bad idea to try to feed pet manures into a worm farm.
You can read up on that in my blog here:



Bird Manures (like chickens)

These are considered VERY HOT manures and should make up no more than 10% of your total inputs to the farm (if used at all).  Personally I think these are best composted in a compost heap.


So, that’s the skinny on things to avoid in the worm farm and why.

Thanks very much for reading my blog – and HAPPY WORMING.
Brian Donaldson



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