Composting is an easy way to reduce waste while improving your yard and garden soils. Yard trimmings and food scraps make up nearly 16% to 30% of waste produced by the average household. In Minnesota, 12% is food scraps and up to 18% is yard waste.
A state law, passed in 1989, bans the disposal of yard waste in landfills or waste-to-energy facilities, so much of our yard waste goes to large commercial composting facilities. However, you can easily compost yard waste in your own backyard.
By composting leaves (browns) with kitchen scraps (greens), you create a dark, crumbly mixture that can be used to improve the soil and reduce your use of fertilizer and water.
Composting "how to"
Getting your own compost bin started can be boiled down to four simple steps:
- Make a compost bin or buy one,
- Throw in yard waste and mix in kitchen scraps
- Add water as needed
- Mix it up with a shovel or pitchfork once in a while.
What's compostable? (and what isn't?)
Like any simple recipe, you'll get the best results if you use the right mix of ingredients to make your compost. The key materials are nitrogen-rich "greens," carbon-rich "browns," water, and air. All of these are essential, but they're easy to mix together for quality compost.
Just say no. While many materials can be composted, there are some items that you should keep out of your home compost pile to minimize odors and keep your pile from attracting scavengers like dogs and raccoons. Since compost is generally used for a soil amendment, you want to keep it free of plant diseases and unhealthy bacteria.
- Food with meat, dairy, or oils
- Pet feces (dog, cat, or bird)
- Diseased plants
- Weeds gone to seed
- Ash from charcoal or coal
Begin with the bin
Location, location, location. Pick a spot in your yard that's:
- Convenient for you to add materials
- Access to water
- Good drainage
- Check with your city to see if they have any location regulations.
- Locate your bin in a shady spot to reduce the need to add water.
Containers. You can compost in a simple pile, but using a container or bin helps compost piles retain heat and moisture, and keeps them neat. To get started, it's easy to go with a single bin system. As materials are added and mixed together, the finished compost settles to the bottom of the bin.
Some assembly required: Build your own bin. Here are some instructions and material lists to build a compost enclosure.
Size. A pile or bin that is 1 cubic yard (3 feet high, 3 feet wide, 3 feet long) is small enough to be easily turned, but big enough to retain heat through most of the year. In the coldest part of the winter, the composting process may stop, but will start up again as soon as it warms up. Home compost piles shouldn't be larger than 5' x 5' x 5'.
Add the first materials
If you're just starting a compost pile, you can measure out greens and browns to create a good mix of materials—for example, an equal mixture of brown autumn leaves and fresh grass clippings will give you an optimal composting combination. Don't worry about getting the mix exactly right, as it's very easy to add material to adjust the pile's performance.
- Lay a base. Start with a layer of browns, laying down 4 to 6 inches of twigs or other coarse carbons on the bottom of the pile for good air circulation.
- Alternate greens and browns. Add layers of nitrogen and carbon materials. Make layers about 4 to 6 inches thick. Once you turn the pile the first time, these materials will get mixed together and compost more efficiently.
- Size does matter. Most materials will decompose faster if they are broken or chopped into smaller pieces, as it makes more surface area available to your composters and water.
- Water as you go. Your compost pile should be moist, kind of like a wrung-out sponge. Squeeze a handful of compost; if small beads of water appear between your fingers, you have enough water. Your pile will get water from rain, as well as the moisture in the greens. For example, fresh grass clippings are nearly 80% water by weight. If the pile gets too wet, you can turn it more frequently to dry it, or add more dry brown materials to soak up excess moisture.
Mix up the pile: As the compost turns
Once you build your pile, the real composters get to work—bacteria, fungi, and insects help break down the materials in your compost bin. As the organic materials decompose and your compost pile is big enough to hold the heat, your pile will get hot on the inside and you might see some steam.
As living things, the microbes in your compost pile need water and air to work and live. Water allows microbes to grow and travel around in the pile to decompose materials. Turning your pile each week with a spade or pitchfork will provide air to aid decomposition and control odors.
Repeat until it's complete. The composting process can be pretty quick in the summer months. Your compost pile may no longer heat up after just a few weeks. Look in your pile for finished compost—material that is dark and crumbly, fresh-smelling, and no longer looks like what you originally put into your bin.
Guess who's coming to dinner Check out who the real compost workers are.
Composting is done by a wide variety of organisms found naturally in organic matter. They work together, feeding on your pile (and each other), to break materials down.
- Bacteria perform the primary breakdown of organic materials. Bacteria aren't added to your compost pile—they're found in almost all forms of organic matter. There are several different types, and they will flourish and reproduce rapidly under the proper conditions.
- Nonbacterial composters, fungi, worms, and a variety of invertebrates, go to work on your pile. Some feed directly on plant tissues, helping bacteria in their role of primary decomposers, while others will actually eat the bacteria. Bugs like centipedes and beetles will feed on the smaller invertebrates.
Using finished compost
Your compost can really pay off in the yard or garden. While compost is not a fertilizer, it can contain nutrients which improve plant growth. By using compost, you can improve the soil and reduce your use of fertilizer and water. You'll learn why gardeners call compost "black gold."
- Mix in compost to improve soil. In sandy soils, compost acts like a sponge, retaining water and nutrients where they can be reached by plant roots. In clay soils, compost makes the ground more porous, creating tiny holes and passageways that help soil drain more quickly.
- Spread compost on your lawn to help fill in low spots.
- Use as a mulch for landscaping and garden plants. Mulches cover the soil around plants, protecting the soil from erosion and the drying effects of wind and sun.
- Mix compost into pots for potted plants.
Common problems and solutions
Home composting isn't very complicated, but the typical composter will likely run into one or more of these common challenges. Learn about some common backyard compost problems.
Winterizing your compost pile
Minnesota winters can be long and cold. If your compost pile is too small, it may stop composting for a while. To keep your compost pile “cooking” in the winter, you will need a pile that is 5' x 5’ x 5’ at all times. That should provide enough insulation to retain heat in the middle of the pile.
Another option is to remove all of the “done” compost and leave your compost bin about ½ empty. This will give you enough room to store the food waste generated over the winter in your bin. The food will freeze which further softens it for composting in the spring when it warms up. In the spring, you add leaves to the bin, mix it with the food scraps and it will start composting again all by itself.
Ideas for apartment and condo dwellers
- Share a compost pile with a neighbor. Offer to help build and turn the pile in return for space.
- Feed kitchen scraps to red worms, right inside your apartment. Learn about composting indoors.