A working compost bin needs air, moisture, and the right mix of materials
A good compost bin holds materials in one place, lets air reach the pile, and keeps rain from waterlogging it while still allowing moisture in. You don't need to buy one—a bin made from wooden pallets, wire fencing, or a plastic storage container works just as well as a commercial model. The key is that it has to let oxygen reach the decomposing materials, drain excess water, and be sturdy enough not to collapse under the weight of a full pile.
The size matters more than the material. A bin that is too small (under 3 feet on each side) won't heat up enough to break down materials quickly. A bin that is too large becomes hard to turn and can develop wet, airless pockets in the middle. A 3-by-3-by-3-foot bin is a practical starting size for most households.
Key Takeaways
- A compost bin must allow air to reach the pile, drain standing water, and be at least 3 feet on each side to heat up properly.
- Wooden pallets, wire fencing, and plastic storage containers all work; the material matters less than having gaps for airflow and drainage.
- The bottom should sit directly on soil so worms and microbes can move in, or have drainage holes if it sits on concrete.
- A lid or cover keeps rain from turning the pile into soup and helps retain heat, but it doesn't have to be airtight.
- The bin location should get some sun, have room to turn materials or remove finished compost, and be close enough that you will actually use it.
Wooden pallet bins are cheap and straightforward to build
Four wooden pallets fastened together at the corners make a functional bin that costs little or nothing if you find pallets at a business that gives them away. Stand the pallets upright so the gaps between the boards face outward—those gaps are your airflow. Bolt or wire the corners together, or use metal brackets and bolts to hold them square.
The floor can be open (pallets sit directly on soil) or closed (a pallet or wire mesh on the bottom). An open floor lets earthworms and soil organisms move in from below, which speeds decomposition. A closed floor keeps rodents from burrowing underneath, though it also means you have to drill or cut drainage holes so water doesn't pool.
Wooden pallets rot over time, especially at the bottom where they touch wet soil. They usually last three to five years before you need to replace them. If you want the bin to last longer, coat the wood with a natural oil or leave-in wood stain (not paint, which blocks airflow). Do not use pallets that were treated with chemicals for shipping—look for ones marked "HT" (heat-treated) rather than "MB" (methyl bromide).
Wire and fencing bins work for small spaces
A cylinder of wire fencing or chicken wire, 3 feet tall and 9 to 10 feet around (which gives you roughly 3 feet of diameter), creates a bin that takes up little floor space and is straightforward to move. find the wire to wooden posts at two or three points, or overlap the ends and wire them together.
Wire bins have excellent airflow but almost no protection from rain or wind. They work best in climates where you can keep the pile moist by hand and where you don't mind materials drying out. The open sides also mean you can reach in to turn the pile without removing a lid, which some people prefer.
Plastic storage containers work for small quantities
A large plastic storage bin (18 to 30 gallons) or a commercial plastic composter can work for apartment dwellers or people with very little space. Drill holes in the bottom for drainage and holes around the sides for airflow—at least a dozen holes total, spaced a few inches apart. Without those holes, the pile becomes anaerobic (airless) and smells like rotten eggs.
Plastic bins heat up quickly because they are small and enclosed, which can speed decomposition. They also keep rain out and retain moisture well. The trade-off is that they fill up fast and are harder to turn. Many people use a plastic bin to collect materials, then dump the contents into a larger outdoor bin to finish composting.
The bottom and drainage matter more than you might think
If your bin sits on bare soil, leave the bottom open. Worms, beetles, and microorganisms will move up from the soil into your pile, and their work is what actually breaks materials down. Water drains naturally into the ground below.
If your bin sits on concrete, a deck, or asphalt, you need a solid bottom with drainage holes. Drill or cut holes at least every 6 inches across the floor so water can escape. Without drainage, the pile becomes waterlogged and anaerobic. You can also set the bin on wooden slats or bricks so air can flow underneath.
Some people line the bottom with hardware cloth (a metal mesh finer than chicken wire) to keep burrowing rodents out while still allowing worms to enter from the sides. This works if you live in an area with a lot of rats or mice, though it also slows the entry of beneficial organisms from below.
A lid or cover keeps the pile balanced
A lid is not required, but it solves two problems: it keeps heavy rain from turning your pile into a soggy mess, and it helps the pile retain heat, which speeds decomposition. The lid does not have to be airtight—in fact, it should not be. Air still needs to reach the pile from the sides and bottom.
A straightforward lid can be a piece of plywood, a wooden frame covered with burlap, or a sheet of corrugated plastic. It should overhang the bin by a few inches so rain runs off to the side rather than down into the pile. Hinges on one side make it easier to open and close without lifting it off entirely.
If you don't have a lid, a tarp or old blanket draped loosely over the top works in a pinch. Just make sure it is not pulled tight—the pile needs to breathe, and you need to be able to add materials without removing the whole cover.
Location and access affect how much you will actually use it
Place your bin where you can see it and reach it easily. If it is hidden behind the garage, you will forget to add materials. If it is 50 feet from your kitchen, you will be less likely to carry scraps out regularly. A spot 10 to 20 feet from your back door, in a corner of the yard or garden, is ideal for most people.
The bin should get at least a few hours of sun a day—this helps the pile heat up and speeds decomposition. It does not need full sun all day. Partial shade is actually better in very hot climates because it keeps the pile from drying out too fast.
Make sure you have room to work around the bin. If you plan to turn the pile with a pitchfork, you need space on at least one side to stand and move materials. If you plan to remove finished compost from the bottom, you need clearance in front. A bin wedged into a tight corner is harder to maintain.
Frequently Asked Questions
Do I need a bin at all, or can I just pile materials on the ground?
You can compost in a pile without a bin, but a bin keeps the pile contained, makes it easier to turn, and looks neater. A pile spreads out and loses heat faster than a binned pile of the same size. A bin also makes it easier to keep rodents out and to separate finished compost from materials still breaking down.
What size bin should I build if I have a small yard?
A 2-by-2-by-2-foot bin is smaller than ideal but can work if you turn the pile frequently and don't add large volumes of material at once. A wire cylinder 2 feet in diameter takes up even less floor space. Many people with small yards use a plastic storage bin or a commercial tumbler instead.
Can I use treated wood or painted pallets in my compost bin?
Avoid wood treated with chemical preservatives—these can leach into your compost. Pallets marked "HT" (heat-treated) are safe. Painted wood is fine as long as the paint is not peeling into the pile. If you are unsure about a pallet's history, use untreated wood or wire instead.
How do I keep my bin from smelling bad?
Bad smells mean the pile is too wet or too airless. Make sure your bin has drainage holes and gaps for airflow. Add dry materials (leaves, shredded paper) along with wet materials (food scraps, grass clippings) to balance moisture. If the pile smells like rotten eggs, turn it or add more dry material to introduce oxygen.
Should I put a bottom on my bin if I have a lot of rats in my neighborhood?
Yes. Use a solid bottom with drainage holes, or line the floor with hardware cloth. Rats are attracted to food scraps in compost, so a closed or screened bottom makes the bin less inviting. You should also avoid composting meat, dairy, or oily foods, which attract rodents more than plant materials do.