Start with a container and the right mix of materials

You create compost by layering brown materials (dry leaves, shredded paper, cardboard) with green materials (food scraps, grass clippings, plant trimmings) in a pile or bin, then letting microorganisms break them down over weeks or months. The pile needs air, moisture, and the right carbon-to-nitrogen ratio—roughly three parts brown to one part green by volume—to heat up and decompose efficiently.

You can start on bare ground, in a wooden bin you build yourself, in a wire cage, or in a purchased plastic bin. The container is less important than having enough material to generate heat. A pile smaller than three feet by three feet by three feet often stays too cool to decompose quickly, while anything larger than five feet by five feet becomes hard to turn and manage.

If you live in an apartment or have limited space, a small sealed bin or tumbler works, though it will take longer and produce less finished compost. The trade-off is that you can keep it on a balcony or in a closet without smell if you manage moisture carefully.

Key Takeaways

  • Layer brown materials (leaves, paper, cardboard) with green materials (food scraps, grass) in a three-to-one ratio by volume to create the right conditions for decomposition.
  • Keep the pile as moist as a wrung-out sponge—wet enough to support microbes, but not so wet that it smells or becomes slimy.
  • Turn the pile every one to two weeks if you want finished compost in two to three months, or leave it undisturbed for six to twelve months for slower decomposition.
  • Avoid meat, dairy, oils, and diseased plants, which attract pests or spread plant diseases to your garden.
  • Finished compost looks dark brown, crumbly, and earthy-smelling, with no recognizable food scraps or leaves remaining.

Gather your brown and green materials

Brown materials are carbon-rich and include dry leaves, shredded newspaper, cardboard (remove tape and staples), straw, wood chips, and sawdust from untreated wood. Green materials are nitrogen-rich and include fresh grass clippings, vegetable and fruit scraps, coffee grounds and tea bags, plant trimmings, and fresh manure from herbivores like horses or chickens.

Start collecting brown materials in fall when leaves drop, and store them in a bag or bin so you have them on hand year-round. Green materials come steadily from your kitchen and yard, so you will have a constant supply. The key is keeping both types available so you can layer them as you add to the pile.

Do not add meat, fish, dairy, oils, fats, diseased plants, or pet waste. Meat and dairy attract rats and raccoons. Oils and fats slow decomposition and create odor. Diseased plants can spread pathogens to your garden when you use the finished compost. Pet waste may harbor parasites harmful to humans.

Build your first layer and establish moisture

Start with a four- to six-inch layer of coarse brown material—wood chips, straw, or crumpled cardboard—directly on the ground or in your bin. This base layer allows air to flow underneath the pile, which is essential for aerobic decomposition. If you are using a bin with a solid bottom, this layer is still important for drainage.

Add a two-inch layer of green material on top, then another four- to six-inch layer of brown. Continue alternating until your pile is at least three feet tall. Water each layer as you build so the whole pile is moist but not waterlogged—squeeze a handful and a few drops should come out, like a wrung-out sponge.

The pile will settle and compress as decomposition begins, so do not worry if it shrinks by half in the first week. This is normal and means microorganisms are actively breaking down the material.

Turn the pile to speed up decomposition

If you want finished compost in two to three months, turn the pile every one to two weeks. Turning mixes the materials, introduces oxygen, and moves cooler outer material toward the hot center where decomposition happens fastest. Use a garden fork or shovel to move material from the outside of the pile to the center, working systematically around the pile.

You will notice the pile heats up—the center can reach 130 to 150 degrees Fahrenheit during active decomposition. This heat kills weed seeds and pathogens, which is why turned compost is safer to use around food plants than unturned compost. The pile will smell earthy and warm, not rotten or ammonia-like.

If you do not want to turn the pile, you can leave it undisturbed for six to twelve months. It will still decompose, just more slowly, and you will get finished compost without the labor. This method works well if you have space and time but limited energy for turning.

Monitor moisture and adjust as needed

The pile should stay as moist as a wrung-out sponge throughout the process. If it dries out, decomposition slows dramatically. If it becomes waterlogged, it will smell like ammonia or rotten eggs because anaerobic bacteria take over and produce those odors.

In dry weather, water the pile with a hose, soaking it thoroughly. In wet weather, cover the top with cardboard or a tarp to shed excess rain. If the pile smells bad, it is too wet—add dry brown material and turn it more frequently to introduce air.

During winter in cold climates, the pile will slow or stop decomposing, but it will not harm the material. Resume turning in spring when temperatures rise, and the pile will heat up again.

Recognize when compost is finished and ready to use

Finished compost is dark brown or black, crumbly, and smells earthy like forest soil. You should not be able to recognize individual food scraps or leaves—everything should be broken down into small particles. If you can still see whole leaves or chunks of food, the compost is not ready yet.

If you turned the pile regularly, finished compost is usually ready in two to three months. If you left it undisturbed, it may take six to twelve months. There is no harm in waiting longer—compost does not spoil once it is finished.

Sift the finished compost through a half-inch screen or hardware cloth to remove any remaining twigs or undecomposed material. Use the finished compost to amend garden beds, mix into potting soil, or top-dress around plants. Store extra compost in a bin or bag in a cool, dry place.

Troubleshoot common problems

If the pile does not heat up, it is usually too small, too dry, or has too much brown material. Add more green material, water it, and turn it. A pile that smells like ammonia has too much nitrogen—add brown material and turn it more often. A pile that smells rotten is too wet—add brown material and reduce watering.

If you see flies or gnats, you likely added meat, dairy, or oil. These materials should never go in a compost pile. Bury any fresh green material under at least six inches of brown material to discourage insects. If rodents are digging in the pile, use a bin with a solid bottom and lid, and avoid meat and dairy entirely.

If the pile is not decomposing at all after several weeks, check that you have a mix of brown and green materials, that the pile is moist, and that it is at least three feet by three feet by three feet. Very small piles or piles made entirely of one material type will not heat up or break down efficiently.

Frequently Asked Questions

Can I compost in winter?

Yes, but decomposition slows significantly in cold weather. In freezing climates, the pile may stop breaking down entirely until spring. You can keep adding materials to the pile over winter and let them decompose slowly, or wait until spring to resume active composting. Insulating the pile with extra brown material helps retain some heat.

How do I know if my compost has enough air?

A compost pile that smells earthy and warm has plenty of air. If it smells like ammonia or rotten eggs, it is too wet and needs turning to introduce oxygen. Turning the pile every one to two weeks ensures consistent air flow. A pile that never heats up may also lack air—check that the base layer is coarse enough to allow air underneath.

What should I do with finished compost if I do not have a garden?

You can use finished compost in potted plants, window boxes, or container gardens on a balcony or patio. You can also offer it to neighbors, community gardens, or local schools. Some municipalities accept finished compost for public parks or landscaping projects. Finished compost stores well in a sealed bin for months without spoiling.

Can I add weeds to my compost pile?

Yes, if the pile heats up enough to kill weed seeds. A pile that reaches 130 to 150 degrees Fahrenheit will kill most weed seeds, which happens when you turn it regularly. If you leave the pile undisturbed, weed seeds may survive and sprout when you use the finished compost. To be safe, avoid adding weeds with mature seeds or invasive perennial roots like bindweed or quackgrass.

Do I need to add compost starter or microorganisms?

No. Microorganisms are already present in soil, leaves, and food scraps, so they will colonize the pile on their own. Commercial compost starters are not necessary and offer no real advantage over letting natural decomposition happen. A healthy pile with the right moisture, air, and mix of materials will heat up and decompose without any additives.