Cheat Sheet: Composting


According to the EPA, 24 percent of the U.S. municipal solid waste stream is composed of food remnants and yard trimmings. If these materials were diverted to another use that kept them out of the trash, a significant portion of the country's everyday waste could be recovered for reuse.

Enter: composting. Grass clippings, food scraps and yard waste are all ideal materials to add to a compost pile. This means that starting one is about more than just creating a great soil booster for your garden or farm - it can cut down on your waste output as well.

For those who have been thinking about starting a pile for some time now, but are still unsure about taking on the challenge, understanding the basics of composting can make it a less intimidating process.

Photo: Flickr/Bunchofpants

It's not as hard as you think! Starting a compost pile is as easy as picking up a bin. Photo: Flickr/Bunchofpants

First Thing's First: What is Composting?

For households, composting is a way to recycle certain materials and kitchen scraps and turn them into a beneficial soil amendment for home gardens and reduce waste output.

For small-scale farms, composting is a way to utilize the residual plant and animal material generated and put it to good use as a fertilizer and soil-builder for future crop production.

In both cases, composting is the natural process of decomposition, sped up by a deliberate strategy in a concentrated environment to transform materials such as grass clippings, vegetable scraps, newspaper and more into a new material (known as "humus") that can then be incorporated back into the soil. Also, composting with worms, or vermicomposting, is another option over traditional composting using outdoor bins.

Check Out: Mega-Machine Turns Compost, Looks Like Spaceship

Break It Down: The Process

So, how does composting work? According to Nance Trautmann and Elaina Olynciw of Cornell University, microorganisms break down organic matter, producing heat, carbon dioxide, water and humus in the process.

When composting is done correctly, a pile undergoes three optimal phases:

  1. The mesophilic, or moderate temperature phase, lasts 2-3 days
  2. The thermophilic, or high temperature phase, lasts anywhere from 3 days to several months, depending on what is in the pile
  3. The cooling and maturation phase lasts several months

In the first stage, what are referred to as mesophilic microorganisms quickly break down the easily degradable materials in the pile. The microorganisms’ output of this breakdown is heat, so the temperature in the pile rise. High temperatures in a compost pile are necessary to ensure that the next phase—where thermophilic (meaning "heat loving") microbes replace the mesophilic ones—ensues.

Thermophilic microbes then kill any pathogens that may exist, as well accelerate the breakdown of complex carbohydrates, fats and proteins that exist in the pile. Important to note is that if temperatures in the pile go above 149 degrees Fahrenheit, even the heat loving microbes can be killed, slowing the rate of decomposition.

Because piles can get too hot, aerating, or turning the pile, is essential if the cooling phase is to be reached. The cooling phase is where the high microbial activity of the other two phases is reduced, allowing for the compost to mature and become ready for application.

More Dirty Details: The Simple Science of Composting

Photo: Flickr/Colin j.

Materials that are ideal for composting include food scraps such as vegetables, fruits and other materials that do not contain animal products or oil and fats. Photo: Flickr/Colin j.

The Do's and Don’ts: What to Add, What to Leave Out

Besides the process itself, knowing what ingredients should go into a backyard composting operation is essential for a successful outcome.

“Green” (nitrogen rich) and “brown” (carbon rich) materials are required to be in proper balance to ensure that the pile does not become anaerobic. Anaerobic decomposition occurs as a result of an improper chemical balance, mainly a lack of oxygen.

Read More: Wow, I Can Compost That?

This lack of oxygen necessitates aeration (turning the pile). If the pile is not properly aerated or has too much nitrogen and not enough carbon, rotting and stinking can occur. A compost pile should never smell, according to the EPA.

So, how to achieve this proper chemical balance? Let’s start with the greens. Green materials refer to those that are rich in nitrogen. Some examples of green materials include:

  • Food scraps - Vegetable peelings are a common material produced by households and make a great compost amendment. However, never add animal-based leftovers (fat trimmings, meat, cheese, milk, etc) as the oils and fats are not conducive to a backyard composting operation.
  • Fresh grass clippings
  • Manure - If you have access to manure from horses, cows, sheep, goats or chickens, it is a great compost ingredient because it speeds up the decomposition process. It is not a requisite for a successful compost pile, however. Never use manure from carnivores.
  • Plants and plant cuttings - Just-picked weeds from around the backyard (as long as there are no developed seeds or seed heads) are permissible, as are flower tops. Green leaves from a freshly cut branch work as well (just make sure to shred them).

Brown materials, on the other hand, are rich in another crucial ingredient, carbon. Carbon gives the microbes the energy they need to work. It is useful to shred most brown ingredients so as to lessen the workload for microbes, enabling decomposition to happen faster.

Some examples of brown materials include:

  • Dead, dry leaves
  • Hay and straw
  • Simple paper products - Newspaper, paper and cardboard
  • Crushed egg shells
  • Coffee grounds - tea bags and loose-leaf tea work as well
  • Wood ashes and sawdust - Use sparingly. Wood ashes can make the pile very alkaline, which limits microbial activity, and sawdust can take a long time to break down.

More Tips: How to Make Top Notch Compost for Your Garden

Photo: Flickr/Suavehouse113

It's amazing what rich soil can yield. Use your compost as fertilizer for your backyard or garden. Photo: Flickr/Suavehouse113

Some Final Tips: Water

According to the EPA, another important factor to keep in mind is the moisture content of the pile, since the hard-at-work microorganisms need an adequate amount to survive. Water also transports nutrients and organic matter throughout a compost pile, which keeps the pile from becoming stagnant.

But how do you tell if water should be added? According to the New York City Compost Project, if you have just loaded the pile with  autumn leaves from the backyard, make sure to add sufficient water to them so that they glisten. Doing so kick starts the decomposition process of the carbon-rich leaves.

Additionally, the NYC Compost Project recommends that "Optimal moisture levels for composting occur when materials are about as moist as a wrung-out sponge—obviously moist to the touch, but yielding no liquid when squeezed."

For advanced-level composting, moisture content instruments are available and can help you to be more precise, although rainfall will often do the trick, as it provides a slow soak that is optimal for a infiltrating a compost pile. For those in a drier climate, however, intentional watering will probably be necessary. Make sure to add water slowly and to turn the pile to incorporate the water so it reaches all sections.

Make It Easy!

To avoid countless trips out to the backyard to dispose of kitchen scraps, put them in an airtight bag and freeze them. This also helps to avoid the smell of old food.

Additionally, freezing will assist in achieving chemical balance in your compost pile. For example, if you have an overload of “green” food scraps from that get-together you had the other night and you do not have the necessary “brown” materials to balance out the pile, freeze the scraps for a while until you have enough "brown" to add to the pile.

Where you live and your particular climate will have a significant effect on your pile, some it occasionally may come down to some experimentation. For more guidance as well as some more advanced composting methods, check out the video below to get started:

  • Silent Spring

    Brilliant article detailing the benefits of compost heaps. Didn’t know that so many different things were going on inside composts. Might try building one myself but I’m really worried that I won’t do it right and it might smell too much.
    Fantastic keep it up!!

  • Lynn Blevins

    Dry leaves can shed water, so compost piles built in the fall can be too dry. Soap can be used as a surfactant to keep leaves moist and hasten the decomposition process. Dissolve your leftover natural soap remains or add biodegradable liquid soap in a few gallons of water and use it to wet the leaves as you build your pile.

    If you are mostly looking to divert your kitchen waste and do not care much about the sicence of composting, then a standard 3’x3’x3′ bin (either a commercial black plastic bin or a homemade wood bin) is very low maintenance. We just throw in our kitchen waste alternating with some dry leaves and it composts just fine without turning, watering or monitoring. I add manure and/or finished compost now and again to keep things going.

  • Pat

    Just a tip grass clippings are good however if you use ex: weed feed on your lawn it should not go into the compost as told to me at a compost seminar , also egg shells should be rinsed/

  • God’spower Martins

    Your presentation on “cheat sheet”, is so revealing to me. I appreciate this environment and soil protection knowledge. I am surely going to put it to use because am quite at home with this theory.

  • K J

    I always heard to add worms to the pile. Maybe that’s just a Michigan thing. But, will worms help?

  • Haley Paul

    Yes K J, take a look at the “vermicomposting” link at the top of the article for more information about composting with the help of earthworms!

  • Jen

    I agree that this is a great article about traditional composting. I think that if you have a big enough yard that you can compost traditionally without experiencing unpleasant smells in your living area. If you do not have a yard or live in a cold climate, you can compost indoors using worms with no bad smells.

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  • kim

    i love all your articles, it would really be nice to be able to print them.

  • Sophie

    loved this article! still a little confused about how exactly do you get started like the whole “hole” thing! my backyard is kind of small….like 2m x 8m its a little more longer than wider. what can i do? does it matter if my backyard is a bit small? really looking forward to start this compost, im just a girl trying to promote greeness in my city and school!

  • Todd Osenbaaugh

    Also in my 1st year to compost. I started with a tumbler last fall which maybe wasn’t the optimal time of year. Over the Winter I have resisted (mostly) the temptation to turn it and now it seems to be dry and dead. Besides water, what should I do to re-start the process, or should I just start over? lost in TX t

  • Creeping Puppy

    I thought you would want to avoid using newspapers because the chemical ink will get into the ground and contaminate things no?

    Wow didnt know composting is such a procedure.

    My grandfather planted flowers and vegs in his front and back yards.

    He simply got fish from the market that was about to be thrown out, chopped them up, mixed it with food scraps and just tossed it over and into the soil where he planted things.

    Granted it all stunk real bad for about a week but no one ever complained about the luscious vegetables and flowers he had. It was so bountiful that he gave away quite a lot of his bounty and people would come back for more.

    But he never followed any of this. He did say he woudl just use food scraps if he didnt have or was unable to get the fish. He said that in the fall he would just turn over the soil again which would cover all the composting.

    He never had a bin. I dont know where he kept all that food scraps though . I think he kept them in bags. maybe thats what the stench in the basement was during the cold winters.

  • Gerrie Baker

    Kudos to Earth911 for promoting organic waste recycling over the internet and through other new communication modalities. In Canada homes, schools, businesses and government offices are learning the valuable benefits of worm composting through our environmental education extention services and we are happy to announce that awareness and participation is rapidly growing. We can look to a future when every citizen takes personal responsibility for their own organic waste recycling at home and in the community. There will be ZERO waste going to the archaic curbside waste collection system. A garbage truck will be museum memoriabillia. Landfill will take on new meaning. Simple, inexpensive, natural solutions that successfully support sustainable systems. Is it possible? YES. Lots of Love, Gerrie Baker, aka The Worm Lady, Foley Mountain, Westport, Ontario

  • Sophie

    Hey guys im trying to start a composting hole in my backyard but im wondering: is it okay if i turn it two days a week like monday and then thursday or something like that? and if not what is the appropriate times of turning it ?

  • Dan

    I’ve found the cheapest way to build a compost bin is to use pallets. You can get pallets for free all over town. Just use three to make the back and sides and a fourth to make the door (if you want it “gated”). For the door make sure you lift off the ground when fastening so it swings clear of the ground (use hinges from local hardware store). If you live in the cold put a roof on it. Down here in South Coastal GA there is no need to have a roof. Use old wire coat hangers to wrap around the posts to secure sides and back pallets. (that’s the cheap way). If you want to put chickenwire around it put it on the outside so it will not get in the way when turning compost. Happy ‘posting everyone.

    Got any questions or comments hit me up at I’m just getting started myself.


  • Greg

    These are all helpful hits in creating a good compost pile. Thanks for the artical. As I get mine going, if I come up with any new tips I will be sure to let all of you know.

  • emory

    Coffee grounds are not a brown (carbon) material. They are a green material, being rich in nitrogen. They can heat a pile hotter than manure.

  • Cary Oshins

    The you tube video has the proportions backwards–it should be one part GREEN to 3 parts BROWN.
    Also, once you are experienced, it is perfectly OK to add some animal-based leftovers. A little cheese or shrimp shells will dissappear quickly. Just remember to ALWAYS bury the food scraps INTO the pile and mix it around so everything is coated with active compost. You should see almost all browns at the surface.

  • Fawnskin’s GG

    Hi Haley, thanks for sharing your link with me. I have a high altitude living blog and we have lots of trouble because of the arid nature of the environment.

    Wondering if you’d be interested in guest blogging a version of this geared toward high altitude issues in our mountain lake resort.

    Take a look and let me know. You know me as @arklady but I am also @fawnskinflyer

  • Lee Wright


    I just started composting and my tumbler is working great, looks exactly like it is supposed to, very exciting! One question though, I have been shredding our cereal boxes and putting them in there. It sounds like those have been treated and should not go in, is that correct? If so, that is such a shame, we go through so many boxes…

    Thanks for the help!

  • don

    don’r forget bokashi as an option to the world of composting….most interesting concept…….

  • Sinfonian

    Odd, I tried finding the article that brought me here through links, but I can’t right now, but it seems there is quite a bit of contridictory information provided here. Coffee grounds are brown, then they’re green, and piles should be 1/3 geen and 2/3 brown, then the opposite. I’m far less technical with my composting and never seem to have problems getting above 140, but THIS is why people get confused with composting.