Start with the right location and container

A compost pile needs a spot that gets partial sun, drains well, and sits on bare soil or grass—not concrete. Bare soil lets worms and microorganisms move in from below. Partial sun (four to six hours a day) keeps the pile warm enough to break down material without drying it out completely.

You can build directly on the ground in a heap, or use a container. A straightforward wire bin made from chicken wire or hardware cloth works well and costs almost nothing. Wooden pallets lashed together create a three-sided box. Plastic bins with drilled holes work for small spaces. The container just needs to let air flow through the sides and bottom—solid walls slow decomposition.

Size matters: aim for at least three feet by three feet by three feet. Smaller piles don't heat up enough to break down material quickly. Larger piles (up to five feet tall) work faster but become harder to turn.

Key Takeaways

  • Layer brown materials (dry leaves, straw, shredded paper) and green materials (grass clippings, food scraps, plant trimmings) in roughly equal amounts by volume to speed decomposition.
  • Keep the pile as moist as a wrung-out sponge—too dry and it stops breaking down, too wet and it smells and attracts pests.
  • Turn the pile every one to two weeks with a pitchfork or shovel to add oxygen, which cuts decomposition time from months to weeks.
  • Finished compost looks dark brown, crumbly, and earthy after four to six months of active turning, or six to twelve months if left undisturbed.
  • Never add meat, dairy, oils, or diseased plants, which attract pests or spread plant diseases to your garden.

Layer browns and greens in the right ratio

Brown materials are dry and carbon-rich: fallen leaves, straw, shredded newspaper, cardboard, wood chips, and sawdust. Green materials are wet and nitrogen-rich: grass clippings, vegetable scraps, coffee grounds, plant trimmings, and manure. The pile breaks down fastest when you layer them roughly equally by volume—not by weight.

Start with a four-to-six-inch layer of brown material on the ground. This creates air pockets at the base. Add a four-to-six-inch layer of green material on top. Repeat until the pile reaches three feet tall. If you add only grass clippings or only leaves, the pile will either become a soggy mat or stay dry and inert.

Shred or chop materials before adding them. Smaller pieces have more surface area for microorganisms to work on, so they decompose two to three times faster than whole leaves or branches. Run a lawn mower over a pile of leaves, or tear newspaper into strips.

Water the pile to the right moisture level

The pile should feel like a wrung-out sponge—moist but not dripping. Squeeze a handful: a few drops of water should come out, not a stream. Too dry and decomposition nearly stops. Too wet and the pile becomes anaerobic (oxygen-starved), which creates foul smells and attracts flies.

Water as you build the pile, especially if you are adding a lot of dry leaves or straw. In dry weather, check the pile's center with your hand every few days. If it feels dry, spray it with a hose until water drips from the bottom. In heavy rain, the pile may become too wet—turn it to add air and let excess water drain.

The pile will heat up as microorganisms work. You may see steam rising on cool mornings. This is normal and means decomposition is happening fast. The center temperature can reach 130 to 150 degrees Fahrenheit in an active pile.

Turn the pile regularly to speed decomposition

Turning adds oxygen, which microorganisms need to break down material quickly. Use a pitchfork or shovel to move material from the outside edges (where it is cooler and less decomposed) to the center. A full turn takes 20 to 30 minutes for a three-by-three-foot pile.

Turn every one to two weeks for the fastest results—finished compost in four to six weeks. Turn every three to four weeks for a slower process that takes two to three months. If you do not turn at all, the pile will still decompose, but it takes six to twelve months and may smell bad in the meantime.

After each turn, the pile will heat up again within a day or two as fresh oxygen feeds the microorganisms. You will notice the material breaking down visibly—leaves and scraps lose their shape and turn into dark, crumbly bits.

Recognize when compost is finished

Finished compost is dark brown or black, crumbly, and smells earthy—like forest soil. You should not be able to recognize the original materials. If you see whole leaves, straw, or vegetable chunks, the pile needs more time or more turning.

A straightforward test: fill a clear jar halfway with finished compost and halfway with water, seal it, and shake hard. Let it settle for 24 hours. If the compost breaks apart and the water stays mostly clear, it is ready. If chunks stay intact or the water is cloudy, decomposition is still happening.

You can use partially finished compost in garden beds or as mulch, but fully finished compost mixes better into soil and does not tie up nitrogen as it continues to break down. Most gardeners sift finished compost through a half-inch screen to remove unfinished pieces, which go back into a new pile.

Avoid materials that slow or ruin your pile

Never add meat, fish, bones, dairy, oils, or fats—these attract rats, raccoons, and flies. Do not add diseased plants or weeds with seeds; the pile may not get hot enough to kill them. Avoid glossy or colored paper, which contains inks and coatings. Do not add pet waste or diseased animal manure.

Grass clippings from lawns treated with herbicides or pesticides can kill the microorganisms in your pile and contaminate the finished compost. If you use clippings, make sure they come from untreated grass. Pine needles and walnut leaves are very slow to decompose and can acidify the pile—use them sparingly.

Citrus peels, onion skins, and garlic take longer to break down than other food scraps but are fine in small amounts. Bread, pasta, and cooked food can attract pests, so bury them deep in the center of the pile where it is hottest.

Troubleshoot common problems

Pile smells bad (like ammonia or rotten eggs): This means it is too wet or has too much green material. Turn it when ready to add air, and mix in dry brown material like shredded leaves or straw. Reduce watering.

Pile is not heating up or breaking down: It is either too dry, too small, or has too much brown material. Add water, turn it, and layer in more green material like grass clippings or food scraps. A pile smaller than three feet by three feet by three feet will decompose very slowly.

Flies or gnats are swarming: You likely added meat, dairy, or cooked food. Bury all food scraps at least six inches deep in the center of the pile. Turn the pile to bury exposed material. Do not add those materials again.

Pile is attracting rodents: Meat, bones, or oily food is the culprit. Remove it if you can, or stop adding it and turn the pile frequently. A wire bin with a solid bottom (not open to the ground) keeps burrowing animals out.

Frequently Asked Questions

How long does it take to make compost?

Four to six weeks if you turn the pile every one to two weeks and keep it moist and balanced. Six to twelve months if you build it and leave it alone. Temperature, moisture, material size, and how often you turn all affect speed. A hot, active pile in summer decomposes faster than a cold one in winter.

Can I use compost that is not fully finished?

Yes. Partially finished compost works as mulch or mixed into garden beds, though it will continue to break down and may temporarily tie up nitrogen in the soil. Fully finished compost is better for starting seeds or potting plants because it is stable and will not heat up as it decomposes.

Do I need to add compost starter or microorganisms?

No. Soil, finished compost, and manure already contain billions of microorganisms. Adding a handful of garden soil or finished compost to your new pile gives it a head start, but a balanced pile with the right moisture will decompose on its own. Commercial starters are not necessary.

What if I do not have space to turn the pile?

Build a second bin next to the first. When the first pile is mostly decomposed, fork it into the second bin—this counts as a turn and mixes it well. Or use a tumbling composter, which you rotate by hand or crank. Stationary piles without turning take longer but still work.

Can I add sawdust or wood chips?

Yes, but in moderation. Sawdust and wood chips are brown materials and decompose slowly. Mix them with plenty of green material and turn frequently. Avoid treated wood or sawdust from pressure-treated lumber, which contains chemicals. Untreated wood from a local mill or tree service works well.