Backyard Composting

Robert Mugaas
University of Minnesota Extension Educator, Environmental Horticulture

Composting is the microbial process whereby organic yard wastes are converted into to a highly desirable, organic, soil-like material. Gardeners have used compost for centuries to increase soil organic matter, improve soil physical properties, and supply some of the essential nutrients for plant growth. Compost also makes an excellent mulch for use in shrub borders, and flower and vegetable gardens. From a home and community standpoint, you can’t help but notice the lighter load you haul out to the trash every week – just think of the implications for our landfills. Even if you don’t need the compost, consider giving your compost to your neighbor, local community gardeners or contact your county for city compost sites.

Getting Started

Place your compost pile in a convenient, level, well-drained location. Partial shade is preferable to full sun. In the case of full sun, the pile can dry out too quickly and too completely, and this will significantly slow down the decomposition process. The opposite is true for full shade. In this situation the pile may remain too wet for too long of time, which may result in unpleasant orders and poor decomposition. Often, the edge of your flower or vegetable garden provides a good compost pile/bin location. Since some municipalities have ordinances regarding the placement of compost piles/bins on a property, it’s a good idea to contact your municipality’s solid waste department for any restrictions that may apply to your location.

Compost Containers

To conserve yard space, speed up the decomposition process, and keep a tidy looking yard, most people choose some type of container in which to actually do their composting. Some counties recycling departments offer discounted compost bins twice a year. See: HOUSE & HOME: Recycling. While ready made containers can be purchased, perfectly suitable compost enclosures can be made from chicken wire, wood, old pallets, hardware cloth, snow fence, concrete blocks, etc. Whatever you use, keep in mind the structure should provide support and allow for good air circulation in and around the pile.

What to Compost

There are many kinds of yard residues and other types of organic materials that are suitable for composting. These include leaves, grass clippings, straw and hay, sawdust, and non-woody plant trimmings. While grass clippings can be composted, they are more beneficial when left on your lawn. If you choose to compost your clippings, they should be mixed with other yard wastes and/or soil to aid decomposition and reduce odors. Because of their potential for disease transmission, human, dog and cat feces should not be placed in compost piles. Also, meat scraps, bones, grease, whole eggs, and dairy products should not be added to compost piles as they can attract unwanted rodents to the area.

Putting it all Together

To function properly, compost piles should be a minimum size of three cubic feet. Bins or piles larger than five cubic feet become too unmanageable to turn easily or carry out other required maintenance. Successful composting begins with four essential components:

  • Organic materials known as “browns” (e.g., straw, sawdust, twigs, dried grass or hay, dry fall leaves). By themselves, browns are very slow to decompose.
  • Organic materials, sometimes known as “greens” (e.g., grass clippings, kitchen and garden scraps, green weeds that have not gone to seed, coffee grounds). Greens provide a critical source of nitrogen in the compost pile that helps speed the decomposition process.
  • Oxygen
  • Moisture

A layering process is a good way to begin building your compost pile. The bottom layer should be about 6 inches thick and contain some coarser materials to help preserve airflow around the base of the pile. Slightly moisten this layer before adding the next layers. Next, add a layer 8 to 10 inches thick containing a mixture of slower decomposing browns and readily decomposable greens. While most of the materials going into your compost pile contain enough microorganisms on their surface for decomposition to occur naturally, soil or some finished compost is sometimes added on the layer’s surface. You can also top this layer with a light application of an organic nitrogen source, such as cottonseed meal or blood meal, at the rate of 1 or 2 cups per 25 square feet of surface area. This will help insure enough nitrogen is available for the microorganisms. Continue to lightly moisten each layer as you construct your pile. Repeat this layering process until the desired height is reached.

Turning the Pile

An actively decomposing pile will reach temperatures of 130-150ºF in its center shortly after being constructed. Your pile should be turned when the inner part of the pile begins to cool. Within the same enclosure, turning can be accomplished by lifting and inverting portions of the compost pile with a garden fork. Turning can also be accomplished by moving the compost from one bin to another. Once turned, the heating process will again occur as new un-decomposed materials are exposed to the inside of the pile. The composting process is essentially complete when mixing no longer produces an increase in heat.

The Gardener’s Black Gold

When the composting process is finished, your pile will be about half its original size and have a pleasant, earthy smell to it. Once finished, you can now focus on returning this “black gold” to your garden and landscape areas where all of its soil-improving benefits can be realized.

Apartment Composting? No way.

Ami Voeltz, The Twin Cities Green Guide

All it took was a phone call to my landlord and the city. I built a compost bin from four donated wooden pallets. I wired the pallets together, put a pitchfork and an empty trash can next to the compost to store dry parts (grass & leaves). We added dry parts every time we created a 2″ layer of wet parts, made up of mostly veggie scraps. I talked to the tenants in our building and posted the composting rules by our back door. The rules: No animal products in the compost and turn the compost once in a while. We really don’t have any yard space, so we usually donate our compost to a community garden. Sometimes tenants use it for potted plants. It feels good to know our food scraps are decomposing. Otherwise they would be tossed into a landfill where they may never get what they need to turn into a beautiful soil, to begin the growth process all over again.


What You Can Do

Home composting need not be complicated or messy. Here are four tips to help you be successful at setting up and managing a home compost pile or bin:

1. Start with a large enough pile to insure good internal heating of the pile. (Minimum size should be 3′ x 3′ x 3′.)

2. Build your compost pile using a mixture of fresh green materials and brown, dry materials.

3. Lightly moisten the contents as they are added to the pile, but be careful to never over-water the pile.

4. Turn the pile over once the heating process has slowed down so that new outer materials can be worked into the center of the pile. This will start the heating process over again.

Backyard Composting

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