How to compost cardboard?

Sheet Mulching: How to Smother Weeds, Build Soil & Conserve Water the Easy Way

But sheet mulching does even more than that.

Beneath the layers of compost materials, sheet mulches typically include a layer of cardboard to keep grass and weeds from growing through – a great way to smother unwanted vegetation or convert a sod lawn into a garden. Before long, both weeds and cardboard decompose and feed the soil with organic matter, while you pat yourself on the back for finding such a clever way to recycle and relieve yourself of the constant chore of weeding.

Sheet mulching also traps moisture in the soil. Every farmer and gardener knows that mulching is a must to cut down on irrigation, but the cardboard used in sheet mulching is much more effective at trapping moisture than typical wood chips or straw. When I used the sheet mulching technique in the parched landscape of California, I found the moisture in the soil lasted at least five to 10 times longer than a thick layer of mulch on its own.

Another reason to try sheet mulching: earthworms love cardboard. They literally eat it and excrete “black gold” from the other end.


The actual process of sheet-mulching is simple:

1. Get the right materials. You’ll need cardboard, mulch and/or organic matter, and manure (but that’s optional). At a minimum, you just need enough cardboard to cover the earth and enough mulch to cover the cardboard. From the there the sky is the limit: You can pile up as many layers of manure and organic matter as you want. Woodchips, straw, leaves, crop wastes, and animal bedding are all examples of organic matter – basically anything you would put in a compost pile, other than kitchen scraps, which you probably don’t want strewn about your yard.

Recycling centers are a great source of cardboard. Unless you are sheet mulching a tiny area, try to grab the biggest sheets of cardboard you can find, such as boxes from bicycles and kitchen appliances, to make things easier. Avoid cardboard with glossy color print, as the ink may not be biodegradable. Some people use a thick layer of newspaper instead of cardboard, which is efficient only for sheet mulching small spaces.

2. Lay down the cardboard. Unless the soil where you’re planning to sheet mulch is already very moist, set up a sprinkler and soak it before laying down the cardboard. Remove all the tape from the cardboard (it’s not biodegradable) and lay the cardboard over the soil/weeds working from one end of the space to the other.

It’s critical to overlap the pieces of cardboard by at least six inches to prevent the more tenacious weeds from weaseling through the gaps to the surface, where they will quickly become re-established in the rich soil you’ve made for them. Once the cardboard is in place, wet it down until it becomes heavy and limp so it doesn’t shift around or blow away in the wind as you add layers of mulch and/or compost materials on top.

3. Add organic matter. If you’re just adding mulch, spread what you have in an even layer at least 2 inches thick on top of the cardboard and call it done. If you’re also using manure, spread it in two-inch layers alternated with a one-inch layer of organic material between each one, finishing with a final layer of mulch on top. Another option is to simply cover the cardboard with finished compost and then cover the compost with a protective layer of mulch.

Important Notes

Late spring when the weeds are getting out of control, but haven’t yet spread their seeds, is a great time to smother them with sheet mulch. But it can be done at any time of year. There are just a couple caveats to keep in mind:

If your goal is to plant perennials – whether fruit trees, edible shrubs, vines, or flowers – you can lay down the sheet mulch first, and come back to plant whenever you are ready, brushing aside the mulch and cutting small holes in the cardboard where you’ll dig the hole for each plant. If your perennials are already planted, work around them.

But if you want to plant annual crops, you need to let the sheet mulch decompose in place for a full year before loosening the soil for planting. If you build a really deep layer of sheet mulch – say, 12 inches or so (which will decompose to probably one-fourth that depth after a year) – you can plant your annuals the following year without even tilling the soil.

The choice between paper, polyethylene and polystyrene egg cartons may come down to recyclability in your neighborhood.

I found myself in an egg carton quandary the other day. I had promised to make cookies for my daughter’s class and had just run out of eggs from my parents’ farm.My parents have a certified-organic farm, so when I visit I’m able to get organic produce, meat and eggs. I save my egg cartons and use them again and again. This is the ultimate in knowing where your food comes from. But, it is when I’m unable to visit and must negotiate the choices at the grocery store that I realized how blessed I am. At the grocery store, an organic farm I know well had its eggs packaged in cardboard cartons, another large brand had its cage-free and organic eggs packaged in polyethylene terephthalate (PET) and still another had its in polystyrene foam packaging. I grabbed the cardboard-packaged eggs because I recognized the farm. But, once I got home, I was curious about what is actually the best packaging choice for the environment.

Pulp paper/cardboard

These cartons are made from low-grade recycled paper. Egg cartons are usually the end of the line for recycled paper because paper quality degrades with continued recycling. According to theTechnical Association of the Pulp and Paper Industry, wood fibers can only be recycled five to seven times before they become too short and brittle to be made into new paper products. A unique benefit of cardboard egg cartons is that you can start seedlings in them. Fill each section with soil and a few seeds. Once the seeds have sprouted, divide the carton into the individual compartments and plant them (carton and all) in the ground. These cartons are biodegradable so they can also be put into your compost bin.The author’s parents’ sustainable farm

Polyethylene terephthalate (PET)

According the Eggland’s Best , the company chose PET for its cage-free and organic eggs not only because it is good for protecting the eggs, but also because the manufacturing process minimizes materials used, energy consumed and waste generated in production. The plastic egg carton is 100% recyclable and is made entirely from 100% recycled materials (recycled soda bottles). The carton is labeled with the #1 recycling code, which can be recycled by most municipal waste-collection agencies. PET can be remanufactured to produce polyester fiber, which is used in carpets, insulating fleece for clothing and containers.

Polystyrene foam

Dolco Packaging is the number one supplier of foam egg cartons to domestic egg manufacturers. Its beige, green and orange foam contains 40% recycled material. And, all of its facilities have in-house recycling programs. As a matter of fact, if your community does not collect and recycle foam egg cartons, you may send clean cartons to: Dolco Packaging PO Box 1005 2110 Patterson St. Decatur, IN 46733-5005 For more information on mail-in and drop-off recycling facilities, visit Dolco Packaging. Recycled polystyrene can be used for many products, such as packaging peanuts, CD jewel boxes, office supplies, video cassette casings and other packaging uses. As more products are packaged in polystyrene foam, more and more communities are accepting this packaging in their recycling programs.

Are egg cartons recyclable?

At Ecobin we’re always happy to help answer your questions on all things recycling, and today we’re heading up the ever-popular – ‘are egg cartons recyclable?

Before answering this question, let me share some information with you. Do you know an average Australian consumes approximately 210 eggs in a year, so now you can estimate the total amount of eggs and their cartons that are thrown into bins annually.

There are three types of egg cartons, let’s get the answer to this question for each type one by one:

    1. Pulp Egg Cartons – These are the most commonly used and eco-friendly egg cartons. They’re made up of pulp which is a slurry that comes out of recycled paper and cardboard mixed with water and fibre grass. They can be recycled like most other types of cardboard. This pulp can also be recycled to create more of these cartons, only if they are thrown into the correct recyclable bin, and if there is no egg stain on them as the food residue can be contaminant for paper recycling. In case the eggs get broken into this carton, they can be thrown into the compostable as this material is completely biodegradable. In fact, it is very good for the soil after being composted. These are the best egg cartons to go for, as they are very eco-friendly.
    2. Foam Egg Cartons – They are made up of styrofoam or polystyrene, or you can call it plastic in simple words. There is no doubt that most of these are non-recyclable as the styrofoam doesn’t break down well in the cycling centers, or some can be recycled to make hard concrete plastics and after that, they are going to be the part of landfills. However, these egg cartons can be reused for the same purpose after their sanitization, as they can be cleaned easily. They can also be re-used for some other purposes like you can use them as small planters, storage for small things like beads, buttons or earrings etc. You can store these cartons and use them later for kids school projects. Also, they can be collected and resold to the poultry farms in bulk where they reuse it for the same purpose. There are some wise people who collect them and then sell them on eBay.
    3. Clear PET Plastic Egg Cartons – These cartons are also very popular over the past few decades. They’re made up of Polyethylene Terephthalate (PET) which again is a form of plastic that is heated to conform to molds. This plastic, however, is recyclable and can be recycled up to 7 times. These cartons are lightweight and transparent to provide clear visibility of eggs and labels. They can be made using recycled PET which helps in saving a lot of energy. You can throw them in the recycling bin, or upcycle them into any kind of storage containers, or you can also use them for art supplies.

Egg cartons are becoming a very important part of people’s lives as the consumption of eggs is growing each day. These cartons are the best way to transport and carry them. Using them wisely and thoughtfully can help us protect the environment and staying healthy. Pride in every egg!!

Trash Tutorial: Fiber egg cartons can be recycled or added to compost

Q: I know that egg cartons are recyclable, both fiber and foam. My question is whether it is OK to cut and nestle a carton in the recycle bin. I am concerned that the cartons must go to your dealers whole.—…

Q: I know that egg cartons are recyclable, both fiber and foam. My question is whether it is OK to cut and nestle a carton in the recycle bin. I am concerned that the cartons must go to your dealers whole.

— Harlan

A: Fiber egg cartons are both recyclable and compostable. They don’t need to be broken down or torn to be recycled (but it’s OK if they are). If you need room in your bin or cart, the cartons can be flattened.

When composting a fiber egg carton, it’s best to tear it into smallish pieces to help the composting process. Fiber egg cartons are a great source of “browns” for compost, which can be tough to come by during the summer months if you haven’t saved leaves from the previous fall.

Foam egg cartons are not recyclable in curbside recycling bins or carts. Konsolidate Warehouse (KWD) in Uxbridge, Mass., will accept the clean, dry foam cartons. It’s a bit tricky to find their warehouse, but follow these directions to the letter: KWD Inc. is about five minutes over the Rhode Island-Massachusetts border. Take Route 146N, to exit 3; make a left at end of exit (16W). Go about a quarter mile and take a left on Douglas Road, where you see the sign for Lenz Corp. A long warehouse building soon appears on your right with many bay doors, and on the far left-hand side of this building (when you are facing it) there is a small storage cage on the loading dock. This cage is where you’ll place your bags of Styrofoam products. KWD does not accept spongy foam or packing peanuts.

Sarah Kite-Reeves, director of recycling services at Rhode Island Resource Recovery, answers questions of general interest posed by Journal readers about recycling, municipal composting, hazardous household waste, waste reduction and other related matters. Send your questions to Trash Tutorial, Features Department, The Providence Journal, 75 Fountain St., Providence RI 02902. You can also email your question to [email protected] Put Trash Tutorial in the subject field.

Cardboard 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

Cardboard 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.

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.

Worm Composting With Cardboard

“Feeding Eisenia foetida (red worms) with cardboard, is it a good idea, how easy is that, and what is the benefit?” ~ Carola Gil

Hi Carola,

Depending on what sort of cardboard you are talking about, it can definitely be a great idea. I use multiple types of cardboard in my beds and bins and the worms seem to absolutely love it.

Can cardboard serve as the sole food source for your worms?

Not likely.

Here are some important considerations…

Are you trying to produce a large, thriving population of juicy red wigglers so that you can sell them? Or are you more interested in the resulting compost (again, as a potential product to sell)?

Perhaps you are taking an even more laid back approach (like myself) and are simply happy to have thriving worm bins/beds so that you can turn your organic waste into a beautiful rich compost for your gardens.

Whatever the case may be, cardboard can definitely be a useful bedding material and food source, but the amount you use (in relation to other materials), will determine how successful your worm farm is.

In my experience, cardboard serves as an excellent bedding material, and eventually becomes a food source over time. On its own however, carboard is typically quite low in nutritional value. Most cardboards have a C:N ratio far higher than the optimal ratio for microbial degradation (20-40:1). Remember, it’s the thriving microbial population that the worms are actually feeding on, so if a material can’t support a healthy population of microbes it’s not typically going to make great worm food.

Cardboard IS however an excellent material you can use to help soak up excess moisture, provide aeration (acts as bulking agent, allowing more air to flow freely), and help you to keep your C:N ratio balanced when large amounts of N-rich materials are being added.

For moisture absorption and overall bedding potential, I definitely prefer egg carton cardboard (same material used for drink holders, and sometimes used as a packing material). It’s kind of like a carboard version of ‘pressboard’ (hopefully that makes sense), and tends to be very absorbent and decomposes quite quickly.

I also really like corrugated cardboard. I use it to line my large outdoor bin, and also shred it and add it as a bedding material. Once it’s moist the worms seem to really gravitate towards it and start inhabiting the inner layers.

One thing I should mention – there have in fact been successful operations that have used wet paper pulp (essentially the equivalent of cardboard in terms of nutritional value) as a sole food source. According to an article in Worm Digest (issue#22: 1999), American Resource Recovery at one time (not sure if they are still in existence) fed 250-350 wet tons each day to its massive red worm population, and produced a high quality worm worm compost.

Some have speculated that the fungal colonization (fungi are better able to consume C-rich materials) provides enough nutritional value for the worms, but this is not known for sure – and not everyone has had the same level of success using paper waste products as a sole food source.

I have personally conducted small-scale university trials using only paper pulp as a food source. Interestingly enough, we saw a very significant increase in reproduction rate, BUT the overall size of the worms seemed to decline by quite a bit – which lead me to believe that the material was not providing enough nutrition (in the form of nitrogen) for worm growth.

Bottomline – in my opinion, cardboard (and similar materials) can definitely serve as an excellent bedding/food material, provided it is not the only material fed to your worms.

Definitely an interesting topic for discussion. Thanks for the great question!

Discover How To Grow Big Fat Composting Worms And Produce More Organic Worm Compost Faster Than Ever Before… Download Our Guide To Worm Composting Here.


See Also…

How To Grow A More Productive Veggie Garden… How To Turn The Food I Grow Into Healthy Hearty Meals… How To Keep Chickens, Rabbits & Other Livestock… How To Turn Herbs Into Natural Health & Wellness… How To Become More Self Sufficient In General…

Red Wiggler Worm Farming Tips and Tails

One might say that as a worm farmer you see treasure where others see trash. Cardboard is one treasure that is very plentiful and easy to find but the problem is that in its raw state it is very unmanageable in a worm bin.

For example if you were to wet cardboard boxes and place them into a worm bin they would eventually be consumed and turned into castings but this would take a long time. Also until the boxes broke down they would be in the way of adding new foods, taking up lots of space, and make sorting or separating of the worms difficult.

Hammer Milled Bedding

However when cardboard is first pulverized it makes an excellent bedding and the worms do seem to get some nutrition from it. I have tried raising worms on straight pulped cardboard and though the worms do survive and even multiply a little it seems that they do best when another food source is used and the cardboard is treated as a bedding. I have even seen that the red wiggler reproduction rates can be increased by the worms growing in cardboard. As far as the actual pulping of the cardboard is concerned it can be very labor intensive.

Lately I have been finding pre-shredded cardboard coming from companies that do lots of shipping. They use specialized cardboard shredding machines make a sort of packaging material from old cardboard boxes. The great part about this stuff is that it is already in a fairly use-able form for the worms. Also, the paper fibers are now cut to short and it cannot be recycled so there is no better use for it. This stuff kind of looks like a fish net made from cardboard and the worms love it so keep your eyes peeled for that bit of worm treasure.

If you happen to have access to a hammer mill than you are in good shape. That is what we use to make our bedding with.

Matthew Wilson

Link to this post!

How to Shred Cardboard for Compost

Personally, I prefer the electric shredder method, and this is why you begin with 8 inch wide pieces so that they feed into the mouth of the shredder. However, a word of warning. I recommend you use a heavy-duty shredder for this (my standard shredder broke down when I tried it with card, but then again, it was only a cheap model).

A good example is this heavy-duty shredder on Amazon which can handle 20 sheets at a time and it will even deal with staples!

A shredder results in cardboard pieces which are light and airy. This is great for composting and in particular for vermicomposting. The shredded paper has a high surface area making it easy break down as the composting microbes ​get to work.

Whichever method you choose, your card is now ready to go on the compost pile!

The Wet Card Technique: Shredding without a Shredder

This idea is pretty simple. If you soak cardboard it becomes easy to tear. Depending on how much card you want to shred and the size of your packaging, you have a few different ways of achieving this. You can even leave the plastic parts in place, since most of the time they become easier to remove after soaking.

For example, if you live in a rainy climate you can leave card outside to begin decomposition. The soaked cardboard will become easier to break up.

Alternatively you can use a large tub to soak card for up to 2 weeks. Cover the cardboard with plenty of water. When it softens you can easily shred the soaked card (to do this I’ve seen some people use a drill with a paint mixing attachment to shred the card).

Lasagna Method

Have you ever stumbled across the concept of lasagna gardening?

Lasagna gardening is a slow compost process that requires little effort. The method begins by laying down sheets of cardboard which then get composted into the underlying soil and vegetation. You then add alternate layers of nitrogen rich green material, and dry carbon rich waste.

You can use this same method in your compost heap by creating alternating layers of cardboard, green and brown organic waste (Sprinkle the layers with water as you go).

You can also spread some soil or old compost over the card to help speed up the process (the soil contains some useful microbes to get the process started). Compost piles are teaming with fungal activity. This cardboard lasagna construction will get broken down by the fungus over a period of a few months. It’s is relatively slow operation and will take at least 3 to 6 months.

You can even leave the plastic tape on your cardboard packaging and remove when everything has broken down.

Quick & Easy Chipper/Shredder Solution

This is probably the quickest solution if you can’t be bothered to do all that cutting and preparation. Using a garden chipper / shredder is instant and effective. It’s instant because you can process your card immediately without any pre-treatment. And a good shredder makes very short work of your cardboard!

The method is easy. Remove any plastic tape etc., then roll your card up into a big cardboard log. Feed this into the chipper and you have shredded card in a flash! (Here’s a demonstration )

There’s just one caveat to this method. You will probably struggle if you have a low powered electric chipper.

This is obviously an investment, but it has the advantage of dealing with all of your other yard debris. Here’s an example of a powerful and efficient chipper / shredder that should make short work of any cardboard and big branches!

How do you shred cardboard to add to your pile?

I did a bunch of reading, and found that many people are not happy with the compost tumblers. Sounds like unless you are diligent about getting the right balance of greens & browns, you end up with green, stinky soupy stuff. Ugh.
I heard really good things about the BioStack Compost bin, which I found at Menards for $90 this Spring. It was super easy to put together (my 7 year old could have done it–easier than Legos, no tools required!), and easy to turn. It is basically 4 plastic squares with pegs on the corners to keep them stacked, and a flip-top lid on top. To turn it, just take off the top square frame, set it beside it on the ground, and start forking the top layer of unfinished compost into it. Keep taking off the frames and transferring the compost over, and water with a hose between layers if necessary.
I’d like to get one of the nice little pails with the charcoal filters for my kitchen. Right now, I just collect scraps in an old ice cream bucket all day, and add them to the pile after dinner. I like to either dig a hole in the compost & bury the food scraps, or add a layer of plant material over top, or else a swarm of gnats and flies will. . well, swarm you when you next open the lid.
I put in coffee grounds & paper filters, tea bags sans staples, any fruit or veggie scraps, melon rinds, moldy bread, basically anything but meat or dairy products, or high-fat items. I poured in several jars of failed homemade sweet pickles last week, and boy, did they break down quickly! ;o) I rinse egg shells a little & crush them after they dry, too. Great source of natural calcium! I do think I should have chopped up the cobs from all the corn I froze, but I know that eventually, this too shall pass.
I also wet down cardboard boxes, like cereal boxes, the huge box the composter came in, etc., and tear into smaller pieces, to add more browns to the mix. Also old newspapers, shredded papers. Seems I always have WAY more greens than browns, since most of what is in it is yard waste. This was my first year using a compost bin, and I think I’m going to start collecting and hoarding bags of leaves this fall, so I can add them gradually all summer with all the grass clippings and yard waste! I searched diligently for straw all summer, and it seems there is just none to be found around here.
My basic impression is that the process is nowhere near as fast as many retailers claim, but I’m not in a hurry. In just three months, I’ve filled my first BioStack, and my second is over half full, so I know two things: 1.) I’ve kept an awful lot of stuff out of the garbage by composting, and 2.) Eventually I’ll have quite the nice haul of “black gold” for my gardens! I’m sure if I was more diligent about turning it weekly, checking temperature, watering frequently, balancing carbons and nitrogens, etc., it would cook away much faster, but for now I’m content with my poky, non-scientific method. And I have volunteer melon and tomato plants all around the perimeter of my bin! :o)

Using Paper & Cardboard in Compost

Cardboard and paper can be a valuable resource for the gardener. Being rich in carbon it is useful for balancing compost ingredient. Used directly as part of a mulch system it suppresses weeds and improves soil quality.

Cardboard torn up for composting

What Cardboard & Paper Can You Use in Compost?

Basically all cardboard and paper can be used in the compost heap or the garden but some shiny cardboard and paper does take longer to breakdown. The shiny surface used to be made using kaolin, a natural clay material, but now it may well be made using plastic like polymers.

There’s no evidence that I’m aware of that shiny card will do any harm in a compost heap but I don’t like the idea of adding a possibly harmful plastic into the environment. Because of that I don’t use shiny cardboard and paper in compost, preferring to put it in the recycling bin.

Coloured matt cardboard or paper can be used. There used to be some concerns about the inks used in the past but these fears seem to have been groundless.

Cardboard packaging usually has plastic tape attached which is best removed before using in the garden. Never shred card with tape attached – thousands of non-degrading bits in the soil that may be harmful to the ecology.

To sum up: What Cardboard & Paper You Can Use in Composting

  • Plain paper – white or coloured
  • Newspaper
  • Brown & coloured non-shiny cardboard (especially corrugated cardboard)
  • Books – but not the cover or glossy photo pages.
  • Tissues and kitchen paper

Carbon Nitrogen Ratio of Cardboard and Paper

Since both are made originally from trees, it’s no surprise that they’re very high in carbon. The carbon nitrogen ration of cardboard and paper is 200:1. This makes them useful for making compost where additional carbon rich ‘browns’ are needed to balance the nitrogen rich ‘greens’

Using Paper in Compost

I shred some paper types – like the standard paper all those letters and bills are printed on before adding to the compost heap. Newspaper and thin papers can just be separated into single sheets and crumpled up.

This helps the paper to break down quickly but it can cause a problem if the other materials in the heap are likely to clump or stick together. Grass clippings are a good example. When wet the paper acts like grass clippings in forming a clump that is impervious to air. This prevents aerobic composting taking place.

With green but stemmy materials like tomato or potato haulm, mixed well the paper provides balancing carbon without producing an airless, non-degrading lump.

Cardboard in the compost heap

Roughly torn into pieces cardboard will rot down well in the compost heap so long as it is mixed in with greens and not layered. Corrugated cardboard works even better because the corrugations hold it open until they decompose.

Cardboard, especially corrugated cardboard, insulates well which is very useful when you have a compost bin with openings in the sides like my bins made from pallets. In winter I just stuff layers of cardboard down the sides which helps hold the heat in the heap.

Sheets of cardboard layered over the top of a compost heap will help hold in warmth but also the water will tend to run off thereby stopping the heap from becoming waterlogged. As the sheets become soaked and start to disintegrate, just add more sheets. They can be incorporated when the heap is turned.

Garden Uses for Cardboard and Paper

Mulching with cardboard or paper and grass clippings.

Mulching in this way has a real benefits – weed suppression and soil improvement being the main ones. There’s a full article on the subject here: Mulching with cardboard and grass clippings.

Trench Lining

Runner bean trenches that hold water for the thirsty plants and provide nutrients for the growth benefit from being lined with a couple of layers of cardboard or three, even four, layers of newspaper.

This lining method, providing nutrients and retaining water, can be used to benefit cucurbits – marrows, courgettes, squash, pumpkins and cucumbers. Prepare the planting position by digging a hole of about 2 spades width and depth. Layer paper or cardboard at the base and even the sides. Then add well rotted manure or compost and backfill with soil.

Cucurbits don’t like being waterlogged but neither do they like drying out. Especially in dry areas of the country – like the eastern areas – holding water will help consistent growth.

More on Composting

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How to Build Compost Bins from Pallets

Building compost bins from pallets has to be the quickest and easiest way to produce a pair of serviceable compost bins. You will need 7 pallets of roughly the same size, some scrap wood, wire, nails and cardboard. Pallets come in different… Cardboard and paper can be a valuable resource for the gardener. Being rich in carbon it is useful for balancing compost ingredient. Used directly as part of a mulch system it suppresses weeds and improves soil quality. What Cardboard & Paper…

Rats in the Compost Heap & Weil’s Disease Safety Concerns

There’s a rat in the compost, what am I gonna do! (apologies to UB40) I was asked if it was safe to use compost on vegetables from a heap where there had been rats. I’ve heard it said that you’re never more than 10 feet from a rat in the…

Ants in the Compost Heap

I was asked this question; My compost heap is overrun by ants – can I use the compost to earth up potatoes and for other uses? The simple answer is yes, compost infested with ants is fine for earthing up potatoes and other outdoor uses. Ants N…

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