It seems like everyone has an excess amount of cardboard nowadays. Whether you’re shopping online, or you know someone who does, or you ask your local grocery store - cardboard is easy to come by. There’s even people on OfferUp or Facebook Marketplace giving away free cardboard boxes. So what should you do with this overabundance of cardboard? Recycle it right?...Wrong!
Cardboard is an excellent source of carbon - which is needed to create compost. And if you live in a large city, apartment complex, or climate similar to mine (i.e. Arizona), cardboard might be the only source of free carbon at your disposal. Here in AZ, we have very few trees that produce large leaves - like what you would see in the Northeast. We also have very poor soil - void of nutrients. So good compost is essential in my climate if you're an avid gardener.
What does carbon have to do with compost you might ask? Well in order to make proper compost, it requires four elements: carbon, nitrogen, oxygen, and water. Carbon (a.k.a. "Browns") can be dead leaves, wood chips, newspaper, and of course - CARDBOARD! Nitrogen (a.k.a. "Greens") can be food scraps, lawn clippings, alfalfa meal, or any leafy greens. Oxygen is self explanatory. Your compost pile simply needs ample amount of oxygen so that the microbes, doing the work for you, can survive and thrive. And lastly, you have to make sure your compost pile remains at a 70% moisture level for your microbes to survive.
Here is a simple chart to see what other items you can use for browns and greens.
So how do I start making compost with cardboard? It's quite easy actually. First, you're going to need an area, or a bucket, or a tumbler, or garbage can, etc. Here at Brown Banana Organics, we started off with 5 gal buckets in our early days.
More recently, we've graduated to 55 gal drums so we could ramp up production.
But for home composters, tumblers are great, and have wonderful aesthetics. But if you're looking for a more cost effective solution, 5 gal buckets or 33 gal garbage cans work just as well. When using 5 gal buckets or garbage cans, be sure to drill 1/4" holes at the top to allow for airflow, and space the holes about 2-4" apart. Less holes means less airflow, which will help retain more moisture. So if you live in a dry climate, maybe start with 4" apart.
Next, you'll want a good amount of cardboard. First, be sure to remove all stickers and DON'T USE cardboard that has a high gloss finish or or any plastic. Only use straight brown cardboard. Cardboard with a matte ink finish is fine. That type of ink is typically food based - soybean ink. Next, shred your cardboard or tear it up into 1"-2" size pieces. Here at Brown Banana Organics, we shred all of our cardboard. Two reasons: 1) efficiency, 2) and it allows for maximum surface area. The more surface area you can create, the faster you'll be able to make finished compost. Plus, shredding is a lot easier and faster than cutting with scissors or tearing by hand.
If you're going to shred cardboard, you'll need a 16-18 sheet shredder. A 12 sheet shredder can work for a period of time, but you'll eventually wear out the motor and have to buy a new one. You also won't be able to shred thicker cardboard. Trust me, I've done it. However, if buying a shredder is not an option, you'll just need to cut or tear the cardboard into smaller pieces. An easy way to tear up cardboard is to soak it first - your hands will thank you later. If you do soak your cardboard, just be sure to dry it out some before adding it to your pile (so as not to add too much moisture to your pile).
Next, be sure to chop up or shred your greens into 1"-2" sizes as well. You won't want to throw a whole lettuce head in your bin. Mix your greens with your cardboard and stick to the 30:1 carbon to nitrogen ratio. Here's a chart to help you calculate how much carbon and nitrogen are in the items you're throwing in your bin. You don't have to be exact, but give it a good guesstimate.
Because cardboard has such a high C/N ratio (roughly 500:1), the rule of thumb is to add 3-4 handfuls of cardboard to 1 handful of greens.
Once you've layered your browns and greens, give it a good mix so everything is combined. Make sure your pile remains moist throughout the process. Technically, it needs to remain at a 70% moisture level for the majority of the composting process. But if you don't have a moisture gauge, simply squeeze the cardboard in your hand and you should only see 1-2 drops of water seep through. If you're seeing more than 1-2 drops, your pile is too wet. If you're not seeing any drops at all, you'll need to add a bit more water to your pile.
Another important piece of information is to be sure to use rain water or dechlorinated water - if you can. You can dechlorinate tap water by leaving it in an open bucket for 24 hrs to off-gas. If you have to use tap water, just know it'll take your bin a bit longer to get going. The chlorine in tap water will prevent your microbes from proliferating for at least 24-48 hours.
Before you add additional water to your bin, be sure to take into account how much moisture your greens will be providing. For example, if you're adding watermelon to your pile, your cardboard may feel dry at first, but in a few days, that moisture from the watermelon will permeate throughout your pile. Whereas, adding lettuce to your bin won't provide a lot of moisture and you will most likely have to add water. Determining moisture level just takes some practice and trial and error. But don't give up. You'll get the hang of it soon enough. It's not "rocket surgery"!
If your pile is too moist, you run the risk of your compost turning anaerobic (which can breed diseases and pathogens) which can be harmful to your plants as well as humans. But if it's too dry, you can always add more water. If it too wet, it's very difficult to remove moisture.
Lastly, add your oxygen. To do this, simply aerate your pile 1-2 times per week. With tumblers, that's simple; all you have to do is turn the tumbler a few times. With a 5 gal bucket, you can use a garden fork or an auger that you can attach to any drill. Same principle applies to larger piles or garbage cans. You may just need a larger auger or pitchfork.
Aeration is important because the microbes in your pile need oxygen to breathe and thrive. It also helps your pile from turning anaerobic, and helps speed up the composting process.
*DON'T MISS*
If your pile has a foul smell after 48 hrs you're doing something wrong and your pile is starting to turn anaerobic. But don't panic. Add more browns to the pile and turn it more often and reassess after 48 hrs. Keep repeating this process until your pile doesn't stink anymore.
In about a week (if done right) you'll start to notice the internal temperature in your compost rise to 95-150º degrees and it shouldn't smell. The larger the pile the higher the temperature. Our 5 gal buckets always maxed out at about 98º degrees. But with our new 55 gal drums, our range is in between 135-160º degrees Fahrenheit. Don't be alarmed by the heat. This means you're doing it right and the microbes are busy working. To check your temps, any garden thermometer will work. Here at Brown Banana we use a simple digital barbecue thermometer with four probe outlets. This allows us to check temps on multiple bins at once. NOTE: checking temps is not a necessary step unless you plan on selling your compost or just overall curious of the progress of your compost.
Once you're compost has reached the point where it doesn't smell, has roughly 70% moisture, and is heating up, don't add any new material. Adding new material at this point will change the composition of your pile, which will delay the timing and your overall process. Your bin/pile is now ready to rock 'n roll. If you have more kitchen scraps, just continue to save it, along with your cardboard, and start a new bin down the road. This is where the 5 gal buckets come in handy. They're cheap, you can keep making new buckets as you have more scraps, and you can stack them.
Throughout this process, continue monitoring the moisture level 1-2 times per week, or every time you aerate it. If you feel your bin/pile is getting too dry, simply add a little bit more water. After about a month, if done properly, you'll notice your compost is beginning to hold moisture very well and you won't have to add additional moisture. This is the humic acid developing. Humic acid is an important component of gardening. It is what allows healthy soil to retain moisture and nutrients. It is the black tar-like substance that is hard to wipe off your hands. Lastly, you'll also notice the material starting to compress about half way and starting to turn dark brown.
In about 2-3 months the material in your compost will have a rich black color and will have compressed about 2/3.
By the third month, the internal temp should be about 80 degrees or less. Once your compost has cooled to about 80 degrees, your compost is ready for use. If your compost still has some unbroken down cardboard or other material, you can give it another few weeks, to a month, to continue decomposing. Just be sure to keep turning it. But by the third or fourth month, if done correctly, your compost should have a rich black color, soil-like texture, and earthy smell.
If your compost finishes sooner than you'd like, don't panic. Just keep turning it every other week (or even just once a month) until you're ready to use it. The compost will just continue decomposing and become finer in texture. The finer your compost the more water soluble it will be. The more water soluble your compost, the more readily available the nutrients will be for your plants.
And that's it! Making compost does take a little practice and some trial and error and experimenting. If you're not successful at first, don't give up. You'll get the hang of it soon.
So if you want free, rich soil - save your CARDBOARD!! Don't recycle it! Compost it!
Here at Brown Banana, our self-made compost is what we feed our worms. It allows for our worm castings to be extremely dense in nutrients. Most compost needs years of decomposition to become water soluble - which is what your plant needs in order to absorb nutrients. By feeding compost to our worms, we speed up that process by a few years, and our end product is fully water soluble and packed with nutrients. It is the last step of decomposition. But that's not all. Worms also add a lot more benefits compared to straight compost. When food passes through the worm's intestinal tract, it adds additional growth hormones, a more diverse population of microbes, mycorrhizae, fungi, nematodes, and essential minerals. It essentially super charges what would've been traditional compost. Studies have shown worm castings are 3-5x more potent than straight compost.
If worm castings sounds like something that interests you, feel free to check out our product page and try out a bag today!
If you have any questions, we're here to help. Drop us a line! Happy gardening!
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