Compost Bins

Compost bin videos:

• Choosing a Compost Bin in 60 Seconds
• Backyard Composting in 60 Seconds
• Using Finished Compost in 60 Seconds
• Winter Composting in 60 Seconds

What are compost bins?

Compost bins are a tidy way to compost outdoors. While optional - you can compost in an open heap - bins keep materials compact and help maintain the damp, warm conditions needed for decomposition. There are many styles of compost bins, including ones that sit on the ground (stationary bins) and ones that rotate on a stand (tumblers).

What style do they fit?

Compost bins are a very versatile way to compost at home. They can be left alone to process slowly or managed closely to process fast. People with a lot of material to compost can get a large bin or several small bins, while people with less to compost can make a smaller set-up.

What space do they need?

Compost bins need to be outside on a permeable surface like grass, soil, or mulch. They work fine in everything from full sun to full shade. Compost bins are best put somewhere easy to reach in all seasons.

Do they work all year?

Material can be added all year but decomposition will only happen in spring, summer, and fall. 

Because materials won't shrink when frozen, compost bins may fill up in winter. A common solution is winter putting kitchen scraps into a secondary outdoor container like a large tub or garbage can. In the spring when the compost thaws the bin will settle and make room for the extra material go on top.

How do they work?

Compost bins rely on naturally present decomposers like bacteria, fungus, and bugs to consume organic material and transform it into humus, the organic component of healthy soil. Using a compost bin is all about creating the right environment for these decomposers to thrive. 

Start by locating your compost bin(s) in a place that is convenient and easy to get to in your yard. They should also be on top of permeable ground like soil, grass, or mulch, so that any extra liquid from the compost can drain into the soil. 

After that, you can simply pile any food waste, yard waste, and garden waste you want into the bin and just wait for nature to sort it out. Left on its own like this, a compost bin may be a bit stinky, or it might take a few years to fully decompose. But it will eventually work.

However if you would like your compost to decompose faster and not smell, there is a basic recipe with 5 ingredients to balance a compost bin and keep it cooking:

 

1. Nitrogen - Aka 'green material,' this includes food waste, green plant trimmings, grass clippings, and herbivore manure. (Manure humans, cats, and dogs is riskier to compost in a home compost bin due to potential pathogens.) These rich materials should make up about half of the compost volume. They are the fuel that speeds up the compost but can be stinky on their own.
2. Carbon - Aka 'brown material,' this includes paper products, cardboard, brown plant trimmings, fall leaves, and wood chips. They should make up the other half of the pile. They compost slow on their own but balance out the rich material so it doesn't smell. It works best to keep a stockpile of 'brown material' and add it on top after each time you add 'green material.'
3. Oxygen - The good microbes breathe oxygen, so we want to keep fresh air in the pile during the spring, summer, and fall. (In the winter it isn't necessary.) Tumbling compost bins can be rotated a few times. Stationary compost bins can either have a pipe with holes drilled in it stuck into the middle of the pile (to act like a drinking straw for fresh air) or, more commonly, given a quick stir with a potato fork or compost aerator. Doing this every couple weeks is ideal.
4. Water - The microbes need water to work. During the spring, summer, and fall, it works best to thoroughly soak the compost every few weeks. This is great time to use rainwater or other untreated water if you have it.
5. Microbes - Microbes are the star of the show. Some will already be there, but you can add extra by adding a shovelful of soil or previously-finished compost every few weeks.

→ Quick tip: Stirring and watering regularly are extra important because they are also the best way to deter mice from taking shelter in the compost. Mice don't hurt compost, but can be a nuisance for other reasons.

→ Quick tip: Plant-based food waste like vegetables, fruits, mushrooms, coffee grounds/filters, tea leaves/bags, and grain products break down quickly in a balanced compost bin. Eggshells also do not cause problems (and don't need to be rinsed). But many animal-based food scraps like meat, bones, eggs, and dairy products have a strong smell when they decompose that can also attract scavenging animals. For that reason, most home composters avoid adding animal products (other than eggshells) to their compost bins.

→ Quick tip: Compostable plastic materials need hot, intense compost conditions to properly decompose. Large industrial compost systems can create the right conditions, but smaller backyard or community garden bins usually can't. For disposable dishware that can decompose in a home compost system, stick to paper or wooden options.

 

If compost stays balanced, damp, and full of air, it should finish decomposing in 3 warm months. Finished compost is dark brown and crumbly, and smells earthy (not sour or like manure). It will still have some lumps of tougher material in it like sticks, pinecones, corn cobs, and fruit pits. These won't bother plants, but can be screened out if you prefer. 

If you have a single compost bin, you will have to take finished compost out by accessing the bottom of the bin and removing all the material that looks/smells finished - and leave the remaining fresher material in the bin to continue decomposing. 

If you have more than one compost bin or a bin with multiple chambers, you can make batches of compost. Keep the oldest batch damp and stirred but don't add any more material. This way, you can finish an entire batch of compost, making it easier to harvest.

Finished compost can be dug into soil, used as a top-dressing, raked onto a lawn, or used in a potting mix blend.

 

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Got more composting questions? Email the Compost Hotline at [email protected].