The basic method: layer, moisten, turn, and wait
Composting works by letting microorganisms and insects break down organic waste into dark, crumbly soil you can use in gardens or potted plants. You build a pile or use a bin, add brown materials (dry leaves, shredded paper, cardboard) and green materials (food scraps, grass clippings, plant trimmings), keep it moist like a wrung-out sponge, turn it occasionally to speed decomposition, and after a few months to a year you have finished compost ready to use.
The process is not complicated because nature does most of the work. You are straightforward creating the right conditions—the right mix of carbon and nitrogen, enough moisture and air, and a warm enough temperature—and then letting billions of microbes and decomposers do what they naturally do.
Key Takeaways
- Layer brown materials (leaves, cardboard, straw) with green materials (food scraps, grass, plant waste) in roughly equal amounts by volume.
- Keep the pile as moist as a wrung-out sponge; too dry and decomposition stalls, too wet and it smells.
- Turn the pile every one to two weeks if you want finished compost in two to three months, or leave it untouched for six to twelve months for a slower process.
- Finished compost is dark brown, crumbly, and smells like soil; use it to amend garden beds or mix it into potting soil.
- Never compost meat, dairy, oils, or diseased plants, as these attract pests or spread plant diseases.
What materials go in and what to avoid
Brown materials are carbon-rich and include dry leaves, shredded newspaper or cardboard (no glossy coatings), straw, wood chips, and sawdust from untreated wood. Green materials are nitrogen-rich and include fruit and vegetable scraps, coffee grounds and tea bags, grass clippings, plant trimmings, and fresh manure from herbivores like horses or chickens.
Never add meat, fish, bones, dairy, oils, fats, or pet waste—these attract rats and raccoons or introduce pathogens. Do not compost diseased plants, weeds with seeds, or plants treated with pesticides, because the pile may not get hot enough to kill them. Avoid glossy or colored paper and cardboard with plastic tape. Citrus peels, onions, and garlic can slow decomposition, so use them sparingly.
Grass clippings and leaves from lawns treated with herbicides should not go in, since the chemicals can persist in the finished compost. If you are unsure whether a material is safe, err on the side of leaving it out—you have plenty of other options.
Choosing between a bin, a pile, and a tumbler
A straightforward pile requires no equipment: stack materials on bare ground in a corner of your yard, and decomposition happens naturally. Piles are free and work well if you have space and do not mind the appearance. The downside is that they take longer (six months to a year) and can attract rodents if you add food scraps.
A bin (made of wood slats, wire, or plastic) contains the pile, keeps it neater, and speeds decomposition slightly by retaining heat and moisture. Bins cost $50 to $200 depending on size and material. A wooden bin is straightforward to build from untreated lumber; a wire bin is cheap and lets air flow freely; a plastic bin is compact and tidy.
A tumbler is a sealed drum on a stand that you rotate to turn the pile without digging into it. Tumblers cost $150 to $400, produce finished compost in six to eight weeks, and keep pests out completely. They work best if you have a small yard or want compost quickly, but they require more effort to fill and turn, and they hold less material than a bin.
Layering and the carbon-to-nitrogen ratio
Start your pile or bin with a layer of coarse brown material (sticks, wood chips, or crumpled cardboard) about 4 inches thick. This creates air pockets at the base. Then alternate layers: 4 inches of brown, 2 to 3 inches of green, 4 inches of brown, 2 to 3 inches of green, and so on. The goal is roughly equal amounts of brown and green by volume, though the exact ratio is forgiving—anywhere from 2:1 to 1:2 (brown to green) will work.
If your pile smells like ammonia or rotten eggs, you have too much green; add more brown material. If it is not heating up or decomposing, you likely have too much brown; add more green or chop materials into smaller pieces so microbes have more surface area to work on. Smaller pieces decompose faster than whole leaves or large cardboard chunks.
Moisture and aeration: keeping the pile alive
The pile should feel as moist as a wrung-out sponge. If it is dry, water it with a hose until liquid drips from the bottom. If it is soggy and smells bad, turn it and add brown material to absorb excess moisture. In dry climates, you may need to water every week or two. In wet climates, you may need to cover the top with cardboard or a tarp to prevent waterlogging.
Turning the pile mixes materials, introduces oxygen, and speeds decomposition. If you turn every one to two weeks, you can have finished compost in two to three months. If you turn every month, expect four to six months. If you never turn it, decomposition still happens but takes six to twelve months. Turning is optional—it just speeds things up.
Use a garden fork or shovel to turn: move material from the outside edges (where it is cooler) toward the center (where it is hotter), and move material from the center outward. This ensures everything gets exposed to the heat and microbes.
Recognizing finished compost and using it
Finished compost is dark brown or black, crumbly, and smells like rich soil or forest floor. You should not be able to recognize the original materials—they are completely broken down. If you still see leaves, cardboard, or food scraps, the pile needs more time.
Use finished compost to amend garden beds (mix 2 to 4 inches into the top 8 inches of soil), fill raised beds, top-dress around trees and shrubs, or blend it into potting soil for containers. You can also use it as mulch around plants, though it will decompose further over time. There is no such thing as too much compost—the more you add, the better your soil becomes.
If you have more finished compost than you can use, offer it to neighbors, community gardens, or local parks. Many gardeners are happy to take it off your hands.
Troubleshooting common problems
Smell like ammonia or rotten eggs: Too much green material or not enough air. Turn the pile and add brown material (leaves, cardboard, straw). Reduce the amount of food scraps you add.
Pile is not heating up or decomposing: Too much brown material, materials are too large, or the pile is too small. Chop materials into smaller pieces, add more green material, and make sure the pile is at least 3 feet by 3 feet by 3 feet.
Rodents or insects in the pile: You have added meat, dairy, or oils. Stop adding these materials when ready. If the problem persists, switch to a closed bin or tumbler. Do not add food scraps to an open pile in areas with rats or raccoons.
Pile is too wet: Cover the top with cardboard or a tarp, turn the pile to introduce air, and add brown material. In very wet climates, consider a bin with drainage holes or a tumbler.
Frequently Asked Questions
How long does it really take to get finished compost?
If you turn the pile every one to two weeks and keep conditions right, two to three months. If you turn monthly, four to six months. If you never turn it, six to twelve months. A tumbler is fastest at six to eight weeks. The exact time depends on temperature, material size, and how often you turn.
Can I compost in winter?
Yes, but decomposition slows dramatically in cold weather because microbes work slower. A pile started in fall will not finish until spring. In mild climates, composting continues year-round. In very cold areas, consider a tumbler in a sunny spot or wait until spring to start a new pile.
Do I need to buy compost starter or microbes?
No. Finished compost, garden soil, or even a shovelful of soil from your yard contains all the microbes you need. Commercial starters are not necessary—nature provides the organisms for free. A layer of finished compost or soil between your green and brown layers will speed things up slightly, but it is optional.
What if I do not have a yard—can I compost indoors?
Yes, with a small indoor bin or worm bin (vermicomposting). An indoor bin is compact and odor-controlled if you use the right materials and keep it moist. Worm bins use red wiggler worms to break down scraps and produce finished compost in three to six months. Both work in apartments or small spaces.
Can I use compost that still has chunks in it?
Yes. Partially finished compost works fine in garden beds—the remaining chunks will continue to break down in the soil. If you want perfectly smooth compost, sift it through a screen or let it sit longer. For most gardening purposes, compost with small chunks is ready to use.