Choosing a composting system for your space, materials and time
What composting is in one pass, then the choice that shapes the rest of this manual: where a system could sit, what you make, and the attention you will give it.
- Start here: the essentials
- What composting is
- Heat is a side effect
- What is not composting
- Three questions that choose a system
- The methods compared
- Combinations are the usual answer
- Why households compost, with the honest numbers
- The science in more detail
- See it: Tomás chooses
- Practice: write the choice
- Your system
- Check your work
- Knowledge check and scenario
Start here Essentials
For a first pass, this chapter asks you to answer three questions about your household and to write one method, with the reason, on your plan. The science and the full comparison are there to help you decide; you do not need to memorize either.
- Describe your place and your time. Save your setup, then answer the three questions in your own words (setup, three questions).
- Read the methods table, filtered to your space and attention. The rows that fit are marked (methods compared).
- Pick one method and write it on the system plan, with the reason. One method is enough for a first pass (system plan).
- Write who decides whether you can put a bin outside. That might be you, a landlord, an association or the city (three questions).
Minimum time: about half an hour. Done when: the system plan names one method, where it would sit, and the reason.
What composting is Understand
Composting is the controlled breakdown of plant and food material by microbes and small animals. Compost is what is left: a dark, crumbly, soil-smelling material that you can mix into soil or spread as mulch. The breakdown itself is decomposition, and it happens whether or not anyone helps it, in a forest floor or a forgotten bag of leaves. Composting is decomposition that you steer by giving the organisms what they need.
EPA lists four things they need (EPA's Composting at Home page): carbon-rich materials, nitrogen-rich materials, water and air. Every method in this manual is a different way of supplying those four, in a different amount of space, with a different amount of attention. Physical principle
| Ingredient | In your kitchen and yard | If it is short | If it is too much |
|---|---|---|---|
| Browns (carbon-rich) | Dry leaves, shredded plain paper and cardboard, wood chips, straw | The pile turns wet and smells; food scraps sit exposed | The pile works slowly and stays cool |
| Greens (nitrogen-rich) | Fruit and vegetable scraps, coffee grounds, fresh grass clippings | The pile is slow to start and stays cool | The pile smells sharp, like ammonia, and gets wet |
| Water (moisture) | Rain, a hose, the water in the scraps themselves | Decomposition slows to a crawl | Air is pushed out of the pile and it turns sour |
| Air (oxygen) | Bulky browns, loose material, turning, holes in a bin | Different microbes take over, and the smell shows it | Not a problem in a home pile |
The words browns and greens are a working sort, not a color code. Browns are dry and rich in carbon; greens are wet and rich in nitrogen. What goes in gives the sort in full, with the one table of ratios behind it. For now, three facts carry most of the decisions in this manual.
- Browns and greens go in together, with more browns by volume. EPA's rule of thumb is two to three times as much browns as greens by volume. Convention Other sources give anything from equal parts to three parts of browns, and the answer in your bin depends on how wet your scraps are.
- The pile should be as damp as a wrung-out sponge. That is EPA's phrase, and every extension service we read uses a version of it. The squeeze test in The slow pile turns it into something you can check.
- Air matters because the main decomposers are aerobic, which means they need oxygen. When a pile is packed down or soaked, oxygen runs out, anaerobic microbes take over, and you smell it. Cornell's composting science pages say anaerobic pockets start to form when oxygen in the pore spaces falls below about 5 percent (Cornell's Compost Physics page).
Who does the work? Mostly bacteria: Cornell's microorganism page puts them at 80 to 90 percent of the billions of microorganisms in a gram of compost, with fungi and actinomycetes (the group behind the earthy smell of good compost) doing their share (Cornell's Compost Microorganisms page). In a backyard pile, mites, sowbugs, millipedes, worms and other small animals shred the material and make it easier for microbes to reach (Cornell's Invertebrates of the Compost Pile page). We name them once and return to them only when one of them shows up in your bin and you wonder whether to worry.
Heat is a side effect
Microbes working fast in a big enough pile give off heat. Cornell describes three phases: a first stage that lasts a couple of days while the pile warms, a hot stage that lasts from a few days to several months, and a cooling and maturing stage of several months. Physical principle A well-kept backyard pile can reach 130 to 160°F by EPA's figures. A small bin of scraps and leaves added a little at a time may not get there, and that is allowed. Heat is something a method can aim for or ignore, and the choice changes what the finished compost can be trusted with.
NC State's backyard composting bulletin gives the figures most home guides repeat: the pile has to exceed 131°F to kill most pathogens harmful to humans and pets, and 145°F to destroy most weed seeds, while temperatures near 160°F can kill the decomposers themselves (NC State's AG-791). Convention Other agencies give slightly different temperatures and different times at temperature; The hot pile sets them side by side under Go deeper. Sources that give temperatures say to read them at the center, where a pile is hottest (New York State's composting guide says so), and a pile that stays cool does not do this work. The University of Vermont's extension puts it plainly: most compost piles do not get hot enough to kill seeds or pathogens (UVM's Three Ways to Compost).
That gives the first rule of this manual about heat: a cool pile still makes compost, but it settles nothing. It does not reliably deal with weed seeds or diseased plants, so those stay out of it (What goes in). A hot pile can deal with more, but only when it is big enough, built at once, kept damp and turned. Most households do not need that, and The hot pile starts with the questions that tell you whether you do.
How big is "big enough"? Texas A&M's composting guide gives about one cubic yard, a cube three feet on each side, as the usual minimum for a pile that heats (Texas A&M's Composting Fundamentals chapter). The pile calculator compares any bin to that figure.
What is not composting
Two things on kitchen counters and under sinks sit near composting without being composting, and this manual says so early because the labels blur them.
- Bokashi is fermentation. You layer scraps, including meat and dairy, with inoculated bran in a sealed bucket. The contents pickle rather than rot. WSU Extension in Kitsap County states it directly: bokashi is fermentation, not decomposition, and the result is a pre-compost that still has to be buried in soil or finished in another system (WSU Kitsap's bokashi page). Bokashi and burying covers it. It earns its place in this manual because it handles what piles cannot.
- Electric food recyclers dry and grind food. A BioCycle review of these appliances, often sold as "composters", says they heat food at roughly 165 to 275°F for 4 to 20 hours and leave a dried, ground material under 10 percent moisture, and it concludes that it is inappropriate to call that material compost (BioCycle's review). BioCycle adds that the maker it reviewed does not call its output compost either. Kitchen and collection explains what the output is and where it can go.
A drop-off site or curbside collection, on the other hand, is a composting system: someone else runs the pile. For a household with no space, no time or no wish to manage a pile, handing the scraps over on a schedule is a complete answer, and Kitchen and collection is a full chapter about it.
Three questions that choose a system
Every guide we compared teaches the methods first and lets you pick one later, as a matter of taste. We start with your household instead, because the household decides most of it. Three questions do the work, and your setup asks the same three.
Question 1: Where could a system sit?
The answer sorts methods fast. With no outdoor space you can use, the candidates are a drop-off or curbside program, a worm bin, a bokashi bucket and a freezer. With a balcony, patio or rooftop you can add small enclosed bins, tumblers and a soil bin for buried bokashi. A small yard opens the enclosed and open bins, trenches, in-ground digesters and a leaf cage. A large yard or land adds multi-bin hot systems and the space for a leaf pile that nobody minds. A shared or community plot opens most of these, but someone else decides.
That last point deserves its own question: who decides whether you can compost outdoors? It might be you. It might be a landlord, an association or a building. It might be the city, through a rule about bins, animals or yard waste. Ask the authority Write the answer on your plan now, even if the answer is "I do not know yet". Site and bin covers how to ask, because a bin you have to remove costs more than one you did not buy.
Question 2: What do you make, and how much?
Food scraps only, or also leaves, grass, garden trimmings and prunings? Do you cook with meat and dairy, and would you rather keep those out of the trash too? The honest answer for most households is "I do not know how much". What goes in has you measure one week of scraps in gallons, because your own week beats any national average. For now, write the kinds of material you expect: they decide which methods can take them, and whether you will have enough dry browns to match your scraps.
Question 3: What will you do each week?
We measure attention in tasks and how often, not minutes. No source we found gives a time per week for any method, and a made-up figure would look like a source's. Oregon State orders its methods by how much fuss they take, and Washington State's master composters ask a short list of questions, including whether you will turn the pile at least once a week (Oregon State's EM 9475, WSU Whatcom's backyard composting brochure). We use four tiers, the same four as your setup.
| Tier | What you do, and how often | Methods that fit |
|---|---|---|
| Drop-off only | Collect scraps in a container (a freezer works) and carry them to a site or put them in a cart, on the program's schedule | Drop-off, curbside |
| Low | Add scraps as they come, cover each addition with browns, check the moisture now and then, and wait about a year | Enclosed bin or open pile, leaf cage, grasscycling, trench |
| Some | A few short tasks a week: feed a worm bin, rotate a tumbler several times a week, add bran to a bokashi bucket | Worm bin, tumbler, bokashi |
| High | Collect enough material, build a batch at once, read its temperature, and turn it about weekly | Multi-bin hot system |
If you are not sure which tier you are, choose the lower one. A method you can keep up beats a faster one you drop in week three, and the plan has a review date (Your compost system) so you can move up or down on evidence.
The methods compared
The table has one row per method, compressed from the full methods table, which adds animal resistance and a filter by space and attention. Time to usable material is a range from the named source, under that source's conditions, and your pile may take longer. Convention
| Method | Space | Takes | What you do | Time to usable material | Heats? | Still needs from you |
|---|---|---|---|---|---|---|
| Drop-off or curbside | Any; a freezer helps | Whatever the program lists | Collect, carry or set out on schedule | Not your pile | The operator's | A program within reach |
| Worm bin | Under a sink, closet, or shade outdoors | Fruit and vegetable scraps, small amounts of cooked food; not meat, dairy, oils | Feed small amounts, check moisture | About 3 to 6 months (NYC) | No | Shredded bedding, red wiggler worms, a spot that stays about 55 to 80°F (NYC) |
| Bokashi | A bucket under a sink | Food scraps including meat and dairy | Layer with bran, drain, seal | About 2 weeks sealed, then weeks in soil (WSU Kitsap) | No | Soil or a pile to finish it in |
| Trench or pit | A garden bed | Food scraps; no meat or dairy | Dig, fill, cover | Plant over it after 3 to 6 months (USask) | No | A bed that can wait, and ground you can dig |
| In-ground digester | Sunny, well-drained soil | Cooked food and meat; not garden waste | Add scraps, empty the basket every few years | Feeds the soil; no compost to harvest (Banyule) | No | Well-drained soil, a purchased unit |
| Tumbler | Balcony to yard | Food scraps and yard material in small volumes | Rotate several times a week, then rest when full | A rest of about 6 to 8 weeks when full (RDCK) | Sometimes; small units may not in winter (Oregon State) | Browns, a unit you can turn when full |
| Enclosed bin, add as you go | A corner of a small yard | Food scraps and yard material | Add, cover with browns, check moisture | About 3 to 5 months if kept well; a year if left alone (EPA) | Usually not | A browns supply all year |
| Open bin or pile, slow | Room for a cube three feet on a side | Food scraps and yard material | Add and cover; mix now and then if you wish | 1 to 2 years if left alone (NC State) | Rarely | Tolerance for neighbors and animals; rodent-proofing if you add food |
| Multi-bin hot system | A large yard | Food scraps and yard material | Build a batch, read the temperature, turn weekly | About a month, then 4 to 6 weeks of curing (Oregon State) | Yes, if built big enough and turned | Enough material for about a cubic yard at once |
| Leaf cage | A yard | Leaves | Fill, wet, wait | A couple of years whole; 6 to 12 months if shredded and tended (Penn State) | No | Leaves, a wire cage |
| Grasscycling | A lawn | Grass clippings | Mow and leave the clippings | Clippings break down in under a week in one study (UGA) | No | A lawn, and a mowing schedule |
Read the table by columns that matter to you. If a method fails your space or your attention tier, it is out; if a method cannot take something you make, you need a second method for it. A drop-off for the meat and dairy next to a bin for the vegetable scraps is an ordinary combination, not a compromise.
This table says what sources report each method needs and accepts. It does not say which method will work for your household, and no method is best. Times are ranges from different sources under different conditions. If you choose a method you then cannot keep up, change the method; your plan has a review date for that (Your compost system).
Combinations are the usual answer
Few households run one method. A closed bin for kitchen scraps and a wire cage for leaves is common: the cage stores the browns that the bin needs. A worm bin for most scraps and a drop-off for meat and dairy covers a kitchen that cooks all kinds of food. A freezer container and a Saturday walk to a market drop-off is a system with no equipment beyond the container. Your plan can carry two methods; Start here asks for one on purpose, so that the first thing you build is small enough to finish.
Why households compost, with the honest numbers
We include one paragraph on why, and we give the numbers with their years, because the usual claims drift. EPA's national overview, whose figures run through 2018, puts food at 21.6 percent and yard trimmings at 12.1 percent of the municipal solid waste generated in the United States that year (EPA's national overview). EPA's 2019 wasted food report estimates that 3.7 percent of the wasted food from households was composted that year, and says the estimate leaves out backyard and community composting, so it is likely an underestimate (EPA's 2019 Wasted Food Report). EPA estimates that landfilled food accounts for about 58 percent of the fugitive methane emissions from municipal solid waste landfills (EPA's page on methane from landfilled food waste).
What we do not say is also on the record. EPA's waste model covers composting only at central facilities, because data on small-scale composting such as backyard piles are insufficient (EPA's WARM version 16 chapters). So no source gives a net climate figure for a home pile. No fetched source gives a household saving, either. This manual makes no money or climate claim for any method. The claim we can make is the narrow one: scraps that go into a bin, a worm box or a drop-off bucket are scraps that do not go into the trash.
Do not buy a bin, a tumbler, worms or a bucket kit before you have chosen a method on your plan and found out who decides. The cheapest mistake in composting is the equipment you did not need.
The science in more detail Go deeper
Four details the chapter left out, for readers who want the reasoning behind the rules of thumb. None is needed to choose a method.
- Carbon to nitrogen by weight. The greens-and-browns sort stands in for the carbon-to-nitrogen ratio, C:N, of the materials. Cornell gives about 30 parts carbon to 1 part nitrogen by weight as the usual target for the start of composting; lower ratios lose nitrogen as ammonia gas, and higher ratios keep a pile cool (Cornell's Compost Chemistry page). Finished compost runs about 10 to 15 to 1 because microbes burn off carbon as carbon dioxide; Cornell says about two-thirds of the carbon is lost that way. What goes in has one table of typical ratios and a worked example.
- Oxygen. Cornell says aerobic microbes survive at oxygen levels as low as 5 percent in the pile's air spaces and that levels above 10 percent are considered optimal. This is why a soaked or packed pile smells: the water fills the air spaces.
- Particle size. Smaller pieces break down faster because microbes work on surfaces. Cornell's particle size page, citing earlier work, says grinding can double the decomposition rate and recommends pieces from about half an inch to two inches (Cornell's particle size page). Too fine and packed, and air cannot get in.
- The three temperature phases. The first stage runs below roughly 40°C (104°F); above that, heat-loving bacteria take over. Cornell says that at 55°C (131°F) and above many microorganisms that are human or plant pathogens are destroyed, and that temperatures over about 65°C (149°F) kill many forms of microbes, including the useful ones.
Two measurements and a model
A Danish study followed six single-family home composting units for a year. Carbon loss ran 63 to 77 percent, mostly as carbon dioxide, but small amounts of methane and nitrous oxide were also measured, and the units that were mixed weekly emitted the most of both (Andersen and colleagues, Technical University of Denmark). It is six units in one country, and it does not give a household a figure to plan on. It is the reason this manual does not claim that home composting is climate-neutral, and it is the reason we do not claim the opposite either.
Where 131°F comes from
The figure that appears in most home guides, 131°F, is 55°C. In federal regulation it appears as a requirement for sewage sludge: 55°C or higher for three days in a within-vessel or static aerated pile, or for 15 days or longer in a windrow with at least five turnings (40 CFR Part 503, Appendix B). That rule is for biosolids treated in controlled equipment. It does not describe a home pile, and nothing in it tells a household how long its own pile needs to stay hot.
See it: Tomás chooses See it
Tomás Reyes is a fictional person, and every fact about him here is invented for this manual. He is 34 and lives alone, renting the downstairs of a duplex in a northern city where the ground freezes from December to March. The fenced backyard is about 18 by 24 feet and he shares it with no one. It has one silver maple. He cooks most nights and drinks coffee every morning. His city has no curbside food scrap collection.
Known: small yard; rented; the ground freezes in winter; no program near him. His assumptions: he expects fruit and vegetable scraps, coffee grounds and the maple's leaves; he wants low attention, which for him means adding scraps and covering them and checking now and then. Open: how much he makes (his scrap log settles it in What goes in); whether his landlord allows a bin (the landlord settles it, in writing, in Site and bin); whether raccoons will bother a bin (Site and bin).
What the table does. His space and tier rule out drop-off, curbside, worm bins, bokashi and a tumbler, because those need a program or tier "some". It leaves an enclosed bin, an open pile, a leaf cage, a trench and grasscycling. A trench in a rented yard might be refused by the landlord. He has no lawn treatment to worry about, and the landlord's mower leaves the clippings.
What he writes on the plan. "Enclosed plastic bin with a lid, add and cover, in the back corner. Reason: small yard, low attention, rented so I can take it with me, and a lid in case of animals. Leaves from the maple, kept in bags, for the browns. Needs: landlord's written yes, a scrap log."
Under these assumptions an enclosed bin fits. The scrap log and the landlord's answer can still change it, which is why the plan says "needs" and has a review date.
Free demonstrations that show the choice being made, from sources we fetched on 2026-10-26:
- UVM Extension, Three Ways to Compost: a short comparison of an open pile, a bin and a tumbler.
- New York State DEC's Home Composting Guide: starts with planning questions, including how much time and effort you can give.
- Oregon State's EM 9475: methods ordered by how much attention each takes.
Practice: write the choice Practice
Minimum: answer the three questions in a sentence each and write one method on the plan with its reason. Time: about 30 minutes, once. Materials: your saved setup, the methods table and the system plan; a pencil if you prefer paper.
- Answer the three questions in your own words. One sentence each: where a system could sit and who decides; what you make and roughly how much; what you will do each week, in tasks.
- Open the methods table with your setup saved. The rows that fit your space and attention are marked. Read them across, noting what each needs that you do not have.
- Pick one method. Write it in the "Methods chosen, and why" line of the system plan, with the reason in terms of space, materials and attention, not in terms of the method's reputation.
- Write where it would sit, and who decides. If someone else decides, write their name or role and "not yet asked".
A second method. If your first method cannot take something you make (meat and dairy, or yard waste), add a second method or a drop-off on the plan, with what it takes. Keep the plan to two methods until you have run the first for a month.
Your system Your system
Check your work Check your work
Criteria
- Does the plan name one method, and does it say where it would sit?
- Is the reason about your space, your materials and your attention?
- Does the plan say who decides whether you can compost outdoors, or say that you decide?
- If the method cannot take something you make, does the plan say where that goes?
Worked example
Tomás's plan names one method (an enclosed bin), a place (the back corner), a reason in terms of space and attention and rental, and the open items (landlord's written yes, scrap log). It does not say meat and dairy, because he said he will put them in the trash; Kitchen and collection asks him to write that line. Noor Haddad, another fictional case, lives on the fourth floor of an apartment with no balcony, wants drop-off only, and writes "freezer container, Saturday farmers market drop-off, May to November, library branch Wednesdays after". Her plan names a method and a place and leaves the worm-bin question as "wait one season, review in Your compost system". Both pass.
Common mistakes
- Choosing by photograph. A tidy tumbler looks like the answer until you add the weight of a full drum to the question "can I turn this?"
- Treating a hot pile as the better method. It does more, and it asks more. Most households do not need what it does.
- Picking two methods to start with. Pick one. Add the second after a month of running the first.
- Leaving the reason off the plan. A method without a reason is hard to review in Your compost system.
What is still unresolved
How much you make is settled by the scrap log in What goes in. Whether you may compost where you chose is settled by whoever decides, in Site and bin. Whether you can keep up the attention you picked is settled by running the method, which is what the log in Your compost system reviews.