Start with the right mix of materials

Compost forms when microorganisms break down organic waste. You need two types of material: browns (carbon-rich) and greens (nitrogen-rich). Browns include dry leaves, shredded paper, cardboard, and wood chips. Greens include grass clippings, vegetable scraps, coffee grounds, and fresh plant trimmings. The ideal ratio is roughly 3 parts brown to 1 part green by volume, though compost will form with less precision—it just takes longer.

Layer your materials as you add them. Start with a 4-inch layer of brown material on the bottom (this helps with air flow), then add 2 to 3 inches of green material, then brown again. Keep layering until your bin or pile is full or you run out of material. If your pile smells like ammonia or rotten eggs, you have too much green material—add more brown and mix it in.

Never add meat, fish, dairy, oils, or pet waste to your compost. These attract rodents and create odor problems. Diseased plants and weeds with seeds should also stay out. Glossy or colored paper and pressure-treated wood do not break down safely.

Key Takeaways

  • Compost needs both brown materials (leaves, cardboard) and green materials (grass, food scraps) in roughly a 3-to-1 ratio by volume.
  • Layer browns and greens as you build your pile or bin, starting with brown on the bottom for air circulation.
  • Turn or mix your pile every one to two weeks to speed decomposition; without turning, compost takes six months to two years.
  • Your compost is ready to use when it looks like dark, crumbly soil and you cannot identify the original materials.
  • Keep meat, dairy, oils, and diseased plants out of your compost to avoid odor and pest problems.

Choose a bin or build a pile

You can compost in a purchased bin, a homemade wooden box, or straightforward a pile on the ground. Bins contain the material and keep rodents out more effectively, but they cost money and limit how much you can compost at once. A pile takes up more space and may attract pests, but it is free and you can make it as large as you want.

If you build a wooden bin, use untreated wood and make it at least 3 feet by 3 feet by 3 feet—smaller bins do not heat up enough to decompose quickly. You can build a straightforward frame from four wooden pallets lashed together with wire or rope. If you use a purchased bin, follow the manufacturer's instructions for assembly and placement.

Place your bin or pile in a spot that gets partial sun and has good drainage. Full sun can dry out your compost too fast; full shade slows decomposition. Avoid placing it directly against your house or fence, because the moisture and smell can damage wood and attract insects.

Add water and turn the pile regularly

Compost needs moisture—think of a wrung-out sponge, not a swamp. If your pile is too dry, decomposition slows dramatically. If it is too wet, it becomes anaerobic (oxygen-starved) and smells like rotten eggs. When you add new material, water it lightly if the pile feels dry. During rain, cover the top loosely with a board or tarp to prevent waterlogging.

Turning (or mixing) your pile every one to two weeks speeds decomposition by introducing oxygen and distributing heat evenly. Use a garden fork to pull material from the outside of the pile toward the center, where it is hottest. If you do not turn your pile, compost will still form—it just takes six months to two years instead of two to four months. Many home composters skip turning and accept the longer timeline.

Monitor the temperature if you can. A hot pile (above 130°F) kills weed seeds and pathogens and finishes faster. You can buy a compost thermometer for about $10 to $20. If your pile never heats up, you likely have too much brown material or not enough green—add more grass clippings or food scraps and mix them in.

Recognize when your compost is finished

Finished compost looks like dark, crumbly soil with an earthy smell. You should not be able to identify the original materials—no visible leaves, cardboard, or food scraps. If you can still see pieces of what you added, it is not ready. Let it sit for another month or two.

Sift your finished compost through a 1/2-inch screen (a piece of hardware cloth stapled to a wooden frame works well) to remove large chunks and return them to a new pile. The fine material underneath is what you use in your garden or potted plants.

Use your finished compost in the garden

Mix finished compost into garden beds at a depth of 2 to 4 inches before planting. You can also use it as a mulch around the base of plants (keep it 2 inches away from the stem to prevent rot) or mix it into potting soil at a ratio of 1 part compost to 2 parts potting soil. Compost improves soil structure, adds nutrients, and helps soil hold water.

There is no such thing as too much compost in a garden bed. If you make more than you can use, store it in a pile or bin and use it as needed over the next season. Finished compost does not break down further and will not heat up, so you can leave it sitting indefinitely.

Troubleshoot common problems

Pile smells bad (ammonia or rotten eggs): You have too much green material or too much moisture. Add brown material (dry leaves, shredded paper) and mix it in. Reduce watering and turn the pile more often to introduce oxygen.

Pile is not heating up: Either you do not have enough material (piles smaller than 3 feet on a side do not generate heat), or your ratio is too heavy on brown. Add more green material (grass, food scraps) and mix it in thoroughly.

Rodents or insects in the pile: Do not add meat, fish, dairy, or oils—these attract pests. Bury food scraps under at least 6 inches of brown material so they are not visible on the surface. If you have a bin without a bottom, consider adding a hardware cloth floor to keep burrowing animals out.

Pile is too wet: Cover the top with a board or tarp during heavy rain. Turn the pile to introduce air. Add more brown material to absorb moisture.

Frequently Asked Questions

Can I compost in an apartment or small space?

Yes. A small bin (12 to 18 inches on a side) works for apartment dwellers, though you will fill it slowly. Alternatively, try vermicomposting (composting with worms in a shallow bin under the sink) or bokashi composting (fermenting food scraps in a sealed bucket). Both produce finished material in weeks rather than months.

How long does it really take to make compost?

With regular turning and the right mix of materials, compost finishes in two to four months. Without turning, expect six months to two years. Temperature, moisture, and the size of your pile all affect speed. A hot, well-maintained pile decomposes fastest; a neglected pile takes much longer.

Can I add cooked food or bread to my compost?

Cooked food, bread, and grains can go in compost, but they attract rodents and insects more readily than raw vegetable scraps. Bury them deep under brown material (at least 6 inches) so they are not visible on the surface. If you have a rodent problem, skip these materials entirely.

What if I do not have brown materials available?

Shredded newspaper, cardboard, and wood chips are the easiest browns to find. You can also use straw, hay, or sawdust from untreated wood. If you live in an area with few leaves, ask neighbors for their yard waste or check if your city offers free wood chips from tree trimming services.

Can I use compost that still has chunks in it?

Partially finished compost with visible chunks will continue to decompose in your garden bed, which is fine. It still improves soil structure and adds nutrients. If you prefer a finer texture, sift it or wait another month for the chunks to break down further.