Start with a container and the right mix of materials

A compost bin works by letting brown materials (dry leaves, shredded paper, cardboard) and green materials (food scraps, grass clippings, plant trimmings) break down together. You need a container to hold them, a location where they can sit undisturbed, and a basic understanding of what goes in and what doesn't. Most home composters start with a straightforward plastic bin or wooden box and add materials as they accumulate.

The simplest setup is a plastic storage bin with a lid, drilled with holes for air flow. You can also buy a dedicated compost tumbler, build a wooden frame from untreated lumber, or use a wire cylinder. The container size matters less than consistency—a bin that holds at least 3 feet by 3 feet by 3 feet will heat up faster and break down materials more quickly, but smaller bins work fine if you're patient.

Key Takeaways

  • A working compost pile needs both brown materials (leaves, paper, cardboard) and green materials (food scraps, grass) in roughly equal amounts by volume.
  • The pile should stay as moist as a wrung-out sponge and get turned or mixed every week or two if you want finished compost in two to three months.
  • Never add meat, dairy, oils, pet waste, or diseased plants, as these either attract pests or spread problems to your garden.
  • A bin in a shaded spot with good drainage underneath will work year-round, though decomposition slows in winter.

Choose a location with shade and drainage

Place your bin in a spot that gets partial shade—direct sun dries out the pile too fast, and complete shade slows decomposition. The ground underneath should drain well so water doesn't pool. If your yard is clay or tends to stay wet, set the bin on a layer of gravel or wood chips to prevent waterlogging.

Keep the bin away from your house if possible, as decomposing materials can attract flies and rodents. A corner of the yard screened by a fence or hedge works well. Make sure you can reach it easily to add materials and turn the pile, and that you have room to move finished compost out when it's ready.

Layer brown and green materials in the right ratio

Start your pile with a layer of brown material about 4 inches deep—shredded leaves, straw, or torn cardboard work well. Then add a layer of green material about 4 inches deep: grass clippings, vegetable scraps, or plant trimmings. Repeat this pattern as you add materials. The goal is roughly equal amounts of brown and green by volume, though exact ratios are forgiving.

Brown materials are high in carbon and break down slowly. Green materials are high in nitrogen and break down quickly. Together they create the right conditions for microbes to work. If your pile smells like ammonia or looks slimy, you have too much green—add more brown. If it's not heating up or breaking down, you probably need more green.

Keep the pile moist and turn it regularly

The pile should feel as moist as a wrung-out sponge. If it's too dry, decomposition stops. If it's too wet, it becomes anaerobic (oxygen-starved) and smells bad. Water it when the top layer feels dry, or after you add dry materials like leaves.

Turning the pile speeds up decomposition by introducing oxygen and mixing materials. If you turn it every week or two, you can have finished compost in two to three months. If you never turn it, decomposition still happens—it just takes six months to a year. A tumbler-style bin makes turning easier. For a stationary bin, use a garden fork to pull material from the outside toward the center.

Know what to add and what to avoid

Safe to compost: vegetable and fruit scraps, coffee grounds and tea bags, crushed eggshells, grass clippings, leaves, straw, shredded paper and cardboard, plant trimmings, wood chips, and sawdust from untreated wood.

Never compost: meat, fish, bones, or dairy (they attract rodents and flies); oils or fats; pet waste or cat litter (they contain pathogens); diseased plants or weeds with seeds (they spread problems to your garden); and glossy or colored paper (the inks and coatings don't break down safely).

Citrus peels, onions, and garlic can be composted but in small amounts—they slow decomposition and can repel worms. Bread and grains are fine but attract pests if not buried under other materials.

Recognize when your compost is finished

Finished compost looks dark brown or black, crumbles easily in your hand, and smells earthy—like forest soil. You should not be able to identify the original materials. This usually takes two to three months if you turn the pile regularly, or six months to a year if you let it sit.

You don't have to wait for every scrap to fully break down. Once the pile has shrunk by about half and the bottom layer is dark and crumbly, you can start using that material in your garden or potted plants while the top layers continue to decompose. Sift out any large pieces and return them to the pile.

Troubleshoot common problems

If your pile smells like rotten eggs or ammonia, it's too wet or has too much green material. Turn it, add brown materials, and let it dry out slightly. If it's not heating up or breaking down, add more green material or turn it more often to introduce oxygen. A pile that's too small (less than 3 feet cubed) may never heat up enough to decompose quickly—add more material or combine it with a neighbor's pile.

Fruit flies or gnats mean you have exposed food scraps. Bury all green materials under at least 4 inches of brown material. Rodents indicate meat, dairy, or oils in the pile—remove them and cover food scraps more deeply. If you see mold, that's normal and actually helpful—it's part of the decomposition process.

Frequently Asked Questions

Can I compost in winter?

Yes, but decomposition slows dramatically in cold weather. A pile that breaks down in three months in summer may take six months or longer in winter. In freezing climates, the pile essentially pauses until spring. You can keep adding materials throughout winter and let them sit until temperatures rise.

Do I need to buy special compost starter or microbes?

No. Soil, finished compost, and plant material already contain all the microbes you need. A handful of garden soil mixed into your pile is enough to get decomposition going. Commercial starters are not necessary.

What if I don't have space for a bin?

You can compost in a small container indoors using a worm bin (vermicomposting), which takes up about as much space as a storage bin under a sink or in a closet. You can also compost in a 5-gallon bucket with a lid, though it will take longer. Some people straightforward pile materials in a corner without a bin and let them decompose naturally.

Can I use compost that still has chunks in it?

Yes. Partially finished compost still improves soil and feeds plants. The remaining chunks will continue to break down in your garden. If you prefer finer material, sift it through a screen before using it, and return the chunks to the pile.

How much finished compost will I get from my pile?

A pile roughly shrinks to about one-third its original volume as materials decompose. A 3-foot-cubed pile will yield roughly 9 cubic feet of finished compost—enough to cover a 100-square-foot garden bed with an inch of compost, or fill several large planters.