Beginners Guide to What Worms Won’t Eat in your Worm Farm

Understanding the types of foods your composting worms (red wrigglers) will AVOID and NOT eat will help prevent some common worm farming mistakes. So to help those new to vermicomposting, we’ve put together a detailed list of foods to avoid adding to your worm farms.

What NOT to Feed Your Worm Farms


  • vermicomposting worms (red wrigglers) survive on a primarily vegetarian diet
  • supplement your worms with a variety of materials, including paper and cardboard
  • find out the foods to avoid, so your worms stay healthy and alive

Okay, we put our hands up and admit that we have made the mistake of adding the incorrect foods to our worm farms.

In fact, one of our mistakes (that we’ll detail later) cost us an entire population of worms. It was a devastating lesson but one we will never forget.

So to help budding vermicomposters avoid these costly mistakes, we’ve put together this quick guide for what NOT to feed your worm farms.

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If you are interested in finding out What Worms LIKE to eat, check out our guide HERE.

What Can’t Worms Eat?

First things first, let’s begin with the essential things – what NOT to feed your worms.

Quick Note: This guide discusses the diet of the most common composting worm for worm castings production, the Red Wriggler worm (eisenia fetida). Some worm farmers use other composting worms, such as nightcrawlers or Indian Blues. However, this worm farm feeding guide doesn’t consider their specific diets.


Eggshells for worm farms

Hang on! Are eggshells good for the garden and worms?

Yes, they are – but just hear us out on this one because we have first-hand experience with eggshells devastating an old worm farm.

A few years ago, we made the rookie mistake of adding large pieces of eggshell to one of our first worm bins.

Not only were the pieces of the shell too large for our worms to consume and process. But as the shells slowly sank to the bottom of the worm bin, they blocked the drainage holes that we had drilled into our bin containers.

This had the devastating effect of a slow but steady build-up of excess liquid called worm wee (not to be confused with worm tea).

Eventually, the worm farm flooded and drowned our entire worm population.

It was a sad, sad day at the Garden Bench Top. 😭😭😭

The good news is you can still add eggshells to feed your worm farm. You just need to know how to process them to make them safe.

Those that want to learn how to grind eggshells the proper way so it doesn’t affect your worm farm, check out our tutorial video


First up on the list of foods that don’t agree with worms is onions. Actually, any vegetable that belongs to the Amaryllidaceae family should be avoided.

Other examples of onion-related food include,

  • shallots
  • spring onions (green onions)
  • scallions

Worms tend to give onions a wide berth because the oils released by onions tend to permeate the worm farm environment, causing aggravation to the worms.

Some vermicomposters say a little bit is okay, but we tend to avoid feeding them completely. We feel it is an unnecessary risk to our wonderful worms.


do not add citrus to worm farms

Another kitchen and garden favorite that you should avoid feeding your worms is citrus fruits and citrus peels. Fruits such as:

  • oranges
  • lemons
  • lime
  • grapefruits
  • mandarins
  • pomelo
  • kumquats

will disrupt the delicate balance in your worm farm and should be avoided at all costs.

Worms require a controlled neutral pH environment between 6.5 – 7.5 because they breathe through their skin. Sudden swings in pH will upset your worms, causing them to dive down into the worm farm, where the pH levels are more steady.

Citrus fruits will cause the pH level to become acidic quickly and drive your worms away from the food scraps. Allowing the food to rot and cause further issues, like mold growth.


don't add meat to worm farms

So, we may have been a bit misleading at the beginning of this article when we said red wrigglers survive on a vegetarian diet.

They can, in fact, eat meat. The problem with meat is it is tougher than vegetables and fruits and takes longer to decompose to a point where red wrigglers can process it.

During this period, the meat tends to rot and release unpleasant odors that can be extremely off-putting. It may also attract other wildlife to your worm farm, causing an entirely different set of problems.

For the above reasons, we avoid adding meat into our vermicompost bins and stick to easy-to-digest organic matter like vegetables, fruits, and unwaxed paper.

Greasy Food

Similarly, processed or oily foods like leftovers from last night’s takeout should also be avoided.

Greasy and processed food tend to have changed properties that make worms avoid it like the plague. As a result, the oils from the greasy food rot and become rancid, affecting the balance of the environment in the worm farm.

On top of that, the rotting oils release an unwelcome odor, which, like the meat, can attract unwanted visitors to your worm farm. Like the rat that chewed its way into an old worm farm.

Damaged worm farm by rat

Spicy Foods

Worms don’t favor foods that deliver spice or heat to our dishes. For example,

  • chili
  • red pepper
  • cayenne peppers
  • jalapeño peppers

They tend to avoid these vegetable scraps because of a compound called capsaicin, which is present in all these foods.

The worms experience the same heat sensation in our mouths when we consume these foods. But for them, the feeling is magnified and causes extreme discomfort.

Dairy Foods

Dairy is also a food that belongs in the DO NOT FEED category for worm bins.

The high-fat content in dairy foods, like cheese, yogurt, and milk products, doesn’t agree with worms. And rather than breaking the dairy products into a usable form, they will leave them to rot.

When it comes to a rule of thumb, freshness is vital for your worms. Anything that is processed, like dairy foods, will take longer to break down and rot – causing your worm bin to contain uneaten food waste and develop a toxic environment.

Pet Feces (poo)

Some worm composters like to add pet feces into their compost piles, which is perfectly acceptable. The worms in the compost will happily process it into a nutrient-rich material.

However, it does take a while for the poo to decompose to the point that will allow the worms to do their thing.

That said, we don’t like adding pet feces to our vermicomposting bins because they are smaller in scale compared to outdoor compost piles.

And the smell that pet feces release is unpleasant – especially when you first lift the lid to your farm.

Usually, the pet feces will become moldy and encourage the wrong types of bacteria to develop on the farm.

So, feel free to add feces to your outdoor compost bin (which is usually far away from the house). But maybe leave it off the menu for your worm composting bin.

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Now that you know what NOT to feed your worms, jump over to our other article, WHAT TO FEED WORMS, to discover their favorite foods.



  • Onion. (2023, February 4). In Wikipedia.
  • Capsaicin. (2023, February 6). In Wikipedia.