Can I Feed Cardboard to Composting Worms? - Uncle Jim's Worm Farm

Can I Feed Cardboard to Composting Worms?

Compost, Red Worms

shredding cardboard for worm beddingCardboard is readily available, but can you feed cardboard to composting worms? Vermicomposting enthusiasts turn trash into valuable organic compost with the help of Red Worms. Obviously, fruit and vegetable scraps are an ideal food to bury in the composting bin. However, most of our household consumables come packaged in cardboard. Can you compost cardboard? Which types of cardboard are best for worms? Can worms live exclusively on cardboard?

Properties of Good Worm Bedding

When you start a composting bin, you need material for the worms to live in. This is called “bedding.” Bedding is typically made from a mixture of coconut coir, pure peat moss, shredded black ink newspaper, partially-decomposed leaves, and/or small amounts of untreated wood chips. Additionally, certain types of cardboard make good bedding.

Bedding needs to contain cellulose. Cellulose gives structure to plants. When worms eat cellulose, they acquire some nutrition. However, worms will also need regular feedings of fruit and vegetable scraps to stay healthy.

The best bedding retains the right amount of moisture. Ideal bedding should feel like a wrung-out sponge when squeezed. The pH of bedding should be neutral — not alkaline and not acidic. And it should be light and fluffy enough to allow air flow and worm movement.

Cardboard as Worm Bedding

corrugated cardboardCardboard is made from trees and is therefore very high in cellulose. Only certain types of cardboard are good for worm bins.

Cardboard that is highly processed, bleached white, coated, shiny, or saturated with colored ink does not make good bedding. The chemicals can be toxic to the worms. Plastic-like coatings will never break down in a worm bin.

Brown corrugated cardboard makes a good worm bedding ingredient. Corrugated cardboard is structured like a sandwich: two outer layers called “liners,” with a “flute” made from recycled paper in the middle. This flute crushes under pressure, thus cushioning the box contents. The flute also provides the fluffiness needed in worm bins. Make sure the corrugated cardboard is not colored, treated, waxed, covered with a plastic layer, or otherwise processed.

Large sheets of brown corrugated cardboard will take a long time to break down in a worm bin. They hinder worm movement and prevent proper drainage. You need to prepare the cardboard first.

How to Prepare Brown Cardboard for Worms

Brown corrugated cardboard needs to be cut into small pieces before adding it to a worm composting bin. To do this:

  1. Inspect the cardboard for excessive grease (such as pizza boxes) and plastic coatings. Oils are not good for worms. They cannot digest plastic. Greasy and plastic-coated corrugated cardboard should not go into the worm bin. Cardboard with plant-based food scraps is fine.
  2. Run the cardboard through a heavy-duty paper shredder. So long as the cardboard is clean and the shredder is powerful enough, you can shred corrugated cardboard quickly.
  3. If the shredder isn’t an option, use scissors or your hands. Snip into small pieces using strong scissors. Tearing by hand is time-consuming. You may find that wearing gardening gloves protects your hands. The smaller, the better. Smaller pieces will break down faster.

corrugated cardboard for vermi composting

When preparing bedding for a new vermicomposting bin, mix shredded corrugated cardboard with one or two other bedding ingredients. See a list in paragraph 2.

Corrugated cardboard can also serve as food for the worms. Mix it into their kitchen scraps occasionally. However, composting worms cannot live exclusively on cardboard.

Can I Feed Cardboard to Worms Exclusively?

No.  Red worms need a varied diet. In the wild, they would munch on whatever food they could find. Corrugated cardboard is an utterly anemic diet that would make anyone sick!

Also, cardboard has a very high carbon-to-nitrogen ratio of 350:1. This is a lot of “brown” and no “green.” Ideal food for a vermicomposting bin has a ratio between 20:1 and 30:1. Putting too many high-carbon substances in the bin slows down composting.

Corrugated cardboard is easy to get. It makes an excellent bedding ingredient. Also, you can mix it into the worm’s food once in a while.

Advanced Tip: Cardboard that has food scraps on it is perfect! The bacteria and fungi have already started to grow on the stains, initiating the breakdown process. Worms eat the microorganisms that are growing on spoiling vegetation. So they love it!

Uncle Jim’s Worm Farm is the #1 supplier of composting worms in the USA. Browse our website for composters, live worms, and composting tips.


20 thoughts on “Can I Feed Cardboard to Composting Worms?

    1. Yes, I use old cardboard egg cartons as bedding all the time. Tear them up into the size of a nickel or smaller, and they hold on to water really well.

  1. Have you heard of PittMoss? It’s a manmade peat moss alternative. I have a bag but have been unsure about adding it to my bins. It’s made from recycled wood and paper products and is 100% cellulose. I am currently using coir as bedding but am interested in the PittMoss as an alternative. I’ve asked the manufacturers but they haven’t responded. As the expert, what do you think?
    Thanks for your time,
    Kevin – Northern California

  2. Can I give the worms paper bags? I am wondering specifically if I can give them these Panera bags. It says they are compostable, but I am not sure if the inks would bother the worms? I am new to this, and I don’t want the worms to get sick.

  3. I use wax paper for maintenance on my paper shredder. After the wax paper has been shred, is it to toss it in the worm bin for bedding?

  4. Off the top from a non-expert, wax is chemically similar to fats and oils, just heavier with a higher melting point. I wouldn’t.

  5. I shred tubes from paper towels and toilet paper as well as any brown paper bags I acquire and mix it into my bedding of dampened peat moss, coffee grounds and a small amount of soil for grit when I start a fresh tray or clean out one.
    Later, if the bins get too wet, I add more of the shredded tubes/brown paper and mix in.
    I often use a damp slab of corrugated cardboard as a blanket. Some of the worms enjoy crawling into the ripples in the center.

  6. How about listing a shredder brand and model that won’t choke on cardboard because, of course, it is thicker than paper.

  7. That’s exactly what I was hoping for! Even a make of paper shredder that’s reliable? And if possible the model that handles corrugated cardboard? Thank you so much anyone who knows about this!

  8. Worms definitely can live on pure cardboard! They won’t absolutely thrive, but they will still be quite happy and healthy, and still reproduce at a decent rate!

  9. Does anyone know the name of a shredder, that will shred cardboard for worm bedding, please let me know!

  10. I use the 18 page microshreder from Costco (<$100). Works very well and makes fast work of amazon shipping boxes. Just remove the packing tape first.

  11. Our waste company does not recycle paperboard, so I’d like to try composting it. The store (Trader Joe’s) reports their colored paperboard packaging does not include plastic and that they are compostable. Anyone have experience mixing this material in a worm bin? Or, is there a way to tell that a retail box is ok to compost? Looking for a way to keep them out of the waste stream.

  12. I cut mine with a rotary cutter, normally used for craft . Works really well, cut dry, presoak then give to .the worms.

    1. I would imagine most of them would be unsuitable, since many of them look ‘shiny’, indicating a possible coating of wax/plastic. They also use a lot of paint which probably isn’t healthy.
      There are, however, some cereal and cookie boxes made by eco-conscious companies that look more suitable– aren’t shiny, seem to use less coloring, etc. I can’t think of a company off the top of my head but anyone who buys organic foods will know what they look like.

  13. I’ve been trying to separate my worms from my finished coconut coir bedding and prepare a new shredded cardboard bedding since it’s much cheaper. I read that Amazon boxes are compostable so been using those after taking the tape off. At any rate, one of the worms got left behind during my attempts of separating everyone but seemed to be okay two weeks later. I found it alone in the leftover shredded cardboard bin.
    I’m hoping cardboard would also make it easier for me to separate the worms from the finished bedding next time. I’ve been using coconut coir as bedding for 2 years and it is EXTREMELY hard to separate them from it, especially the little ones! Worms do like their junk pile, and nothing, not even putting food in a clean area to tempt them over, seems to work fully.

  14. When I try to use good quality cardboard boxes for my worms, I always cut it, then soak it for a few hours. I found it easier to shred by hand this way.
    I am just concerned about the amount of glue between layers and I quickly try to rince some.
    Is this kind of glue toxic or not?

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