The simplest compost bin is a wooden box or wire cylinder you fill with layers of brown and green material

You do not need to buy a compost bin. A compost bin is any container that holds decomposing organic matter in one place long enough for it to break down into usable compost — usually four months to two years depending on the method and climate. The fastest and cheapest option is a wooden frame made from untreated lumber, a wire cylinder made from chicken wire or hardware cloth, or a plastic storage bin with holes drilled in the bottom and sides.

The bin itself does not make compost; the microorganisms and insects in the material do. Your job is to contain the pile, keep it moist, add the right mix of materials, and turn it occasionally if you want faster results. A bin prevents rodents from tunneling into the pile, keeps the pile neat, and makes turning easier than composting on the ground.

Key Takeaways

  • A wooden box, wire cylinder, or plastic bin with drainage holes all work equally well and cost between $0 and $50 depending on materials you have on hand.
  • The bin needs drainage holes in the bottom and air holes in the sides so water drains and oxygen reaches the decomposing material.
  • You fill the bin with alternating layers of brown material (dry leaves, straw, cardboard) and green material (grass clippings, food scraps, plant trimmings).
  • Turning the pile every two weeks speeds decomposition to three to four months; leaving it untouched takes one to two years but requires no work.

Building a wooden bin from untreated lumber

A wooden bin is the most common homemade option. You need four pieces of untreated wood (cedar, oak, or pine), each 3 to 4 feet long and 12 inches tall. Avoid pressure-treated lumber because the chemicals leach into the compost. Screw or nail the boards into a square or rectangle using corner brackets or by overlapping the corners. The finished bin should be at least 3 feet on each side — smaller piles do not heat up enough to decompose quickly, and larger ones become hard to turn.

Drill or cut 1-inch holes in the bottom board to let water drain. Drill or cut 1-inch holes every 6 inches up the sides to let air in. You can leave the bottom open to the soil so worms and microorganisms can move in from below, or nail a piece of hardware cloth (metal mesh) to the bottom to keep out burrowing rodents. Attach a hinged lid or removable boards on one side so you can turn the pile and remove finished compost from the bottom.

Making a wire cylinder bin

A wire cylinder is faster to build and takes up less space than a wooden box. Buy a roll of 1/4-inch hardware cloth or chicken wire at least 3 feet tall and 12 to 15 feet long. Form it into a cylinder 3 to 4 feet in diameter and find the overlapping ends with wire, zip ties, or hose clamps. The gaps in the mesh provide all the air circulation you need, so you do not need to drill additional holes.

Set the cylinder on bare soil or on a piece of hardware cloth laid flat on the ground. The open bottom lets worms and microorganisms enter from below. A wire bin is lighter and easier to move than wood, and you can lift the entire cylinder off the pile when you want to turn it — the pile stays in place and you slide the bin over to the side, then slide it back over the turned material.

Using a plastic storage bin or trash can

A large plastic storage bin or trash can works for small-scale composting in apartments or tight spaces. Drill 1/4-inch holes in the bottom for drainage and 1/4-inch holes every 2 inches up all four sides for air. Drill holes in the lid as well. The bin should hold at least 18 gallons to generate enough heat for decomposition; smaller bins work but take longer.

Place a tray or old baking sheet under the bin to catch liquid that drains out — this liquid, called compost tea, can be diluted with water and poured back into the bin or used on plants. A plastic bin is rodent-proof and works well in cold climates because the dark color absorbs heat. The trade-off is that it holds less material than a wooden or wire bin, so you may need to wait longer for finished compost or empty it more often.

Filling the bin with the right materials

Start with a 4-inch layer of coarse material like straw, wood chips, or shredded newspaper on the bottom. This creates air pockets. Then alternate 4-inch layers of brown material (dry leaves, shredded paper, cardboard, straw) and green material (grass clippings, food scraps, plant trimmings, coffee grounds). Aim for roughly three parts brown to one part green by volume — too much green material makes the pile smell like ammonia, and too much brown material slows decomposition.

Chop or shred large pieces before adding them; smaller pieces decompose faster. Avoid meat, fish, dairy, oils, and pet waste because they attract rodents or introduce pathogens. Avoid diseased plants or weeds with seeds. Wet each layer as you add it so the pile feels like a wrung-out sponge — moist but not dripping. If the pile smells bad, add more brown material and turn it to add air.

Turning the pile versus leaving it alone

Turning the pile every two weeks speeds decomposition to three or four months because it adds oxygen, which microorganisms need to work fast. Use a pitchfork or shovel to move material from the outside of the pile to the center, where it is hottest. The pile will heat up to 130 to 150 degrees Fahrenheit during active decomposition — hot enough to kill weed seeds and pathogens.

If you do not want to turn the pile, leave it alone and it will decompose on its own in one to two years. This cold composting method requires no work but takes longer and does not kill weed seeds or pathogens. Either method produces usable compost — finished compost is dark brown, crumbly, and smells like soil.

Maintaining moisture and temperature

The pile needs moisture to decompose but should not be waterlogged. If it is too dry, add water with a hose. If it is too wet or smells like ammonia, turn it and add brown material. In winter, the pile slows down or stops decomposing because microorganisms work slowly in cold. In summer, it may dry out faster. A bin with a lid or cover helps retain moisture and heat.

You can speed decomposition by adding a compost accelerator — a product containing microorganisms or nitrogen — but it is not necessary. Finished compost forms first at the bottom of the bin, so you can remove it from the bottom while the top layers are still breaking down. This lets you harvest compost while still adding new material to the top.

Frequently Asked Questions

How much does it cost to build a compost bin?

A wooden bin costs $20 to $50 if you buy new lumber, or free if you use scrap wood. A wire cylinder costs $15 to $30. A plastic storage bin costs $20 to $40. If you already have materials on hand, the cost is zero.

Can I use treated wood for the bin?

No. Pressure-treated lumber contains chemicals that leach into the compost and can harm plants. Use untreated cedar, oak, pine, or reclaimed wood. Avoid wood that has been painted or stained.

What size bin do I need?

A bin at least 3 feet on each side (27 cubic feet) generates enough heat for fast decomposition. Smaller bins work but decompose more slowly. A 3-by-3-by-3-foot bin is a good starting size for a household.

How do I know when the compost is ready to use?

Finished compost is dark brown or black, crumbly, and smells like soil. You should not see the original materials — leaves, food scraps, or paper should be unrecognizable. If you see recognizable pieces, the compost is not ready yet.

Can I compost in winter?

Yes, but decomposition slows dramatically in cold weather. A pile that decomposes in four months in summer may take a year in winter. A bin with a lid or cover helps retain heat. In very cold climates, many people stop adding material in fall and restart in spring.