Home composting is a simple way to recycle yard waste and kitchen scraps into a nutrient-rich soil amendment. The University of Minnesota Extension explains that adding compost to light, sandy soil helps it hold moisture and nutrients, while incorporating it into heavy clay soil improves drainage. Purdue University notes that home composting can significantly decrease the amount of food waste sent to landfills, where organic material makes up a large portion of discarded items.

Short version: Build a pile 3 to 5 feet wide, layer browns (carbon-rich materials like dry leaves) and greens (nitrogen-rich materials like grass clippings), keep it moist but not soggy, turn it once or twice a month, and in two to four months you’ll have finished compost.

Why Compost at Home?

Composting harnesses naturally occurring microbes to break down organic matter into a useful product. The University of Minnesota Extension states that gardeners have used compost for centuries to improve soil structure and support plant growth. Beyond the garden, composting reduces the volume of waste that ends up in landfills. According to Purdue University consumer horticulture extension specialist Karen Mitchell, between 30 and 40 percent of food in the United States is wasted, and much of that could be turned into natural fertilizer instead of taking up space in a landfill.

Finished compost is often called “black gold” because of its ability to improve soil health. It adds organic matter, increases water-holding capacity, and provides a slow-release source of nutrients. For a deeper look at starting a garden from scratch, see our Gardening for Beginners guide.

What to Compost: Browns, Greens and Materials to Avoid

A successful compost pile needs a balance of carbon-rich “browns” and nitrogen-rich “greens.” Purdue’s Mitchell explains that the ideal carbon-to-nitrogen (C/N) ratio is about 30 to 1, meaning roughly 30 times more browns than greens. Browns include dry leaves, wood chips, shredded paper, and sawdust. Greens include fresh grass clippings, plant trimmings, and vegetable scraps. The University of Minnesota Extension adds that small amounts of wood ash and sawdust can be composted, though sawdust requires extra nitrogen and wood ash can raise the pile’s alkalinity.

Not all organic waste belongs in a home compost pile. The University of Minnesota Extension advises against composting pet feces, which can transmit diseases, as well as meat, bones, grease, whole eggs, and dairy products because they attract rodents and other animals. Purdue University also warns against adding meat scraps, bones, oils, or fats. Badly diseased or insect-infested plants and weeds that have gone to seed may not heat up enough to be decontaminated, so the University of Minnesota Extension recommends keeping them out.

Building Your Compost Pile: Size, Location and Structures

The University of Minnesota Extension recommends a pile that is 3 to 5 feet wide in each direction. A smaller pile won’t generate enough heat for efficient decomposition, while a larger pile restricts the flow of air and water. Choose a location close to where you will use the finished compost, away from drying winds, but with partial sunlight to help heat the pile.

You can contain the pile in a simple structure to keep materials from blowing away and to insulate the center. The University of Minnesota Extension describes several options: a wire fencing bin that can be easily moved for turning, a cement block or brick bin with gaps for aeration, a rotating barrel, or a portable wood-and-wire bin. A three-chambered bin works like an assembly line: start material in the first bin for three to five weeks, turn it into the middle bin for another four to seven weeks, and move it to the last bin as finished or nearly finished compost. For more bin ideas and setup tips, visit our Composting section. If you plan to dig post holes for a permanent bin or prepare a new garden bed, contact 811 a few business days before you dig to have underground utilities marked.

Managing the Pile: Chopping, Turning, Moisture and Temperature

The smaller the pieces, the faster they break down. The University of Minnesota Extension suggests using a shredder or power mower to chop leaves and small twigs before adding them to the pile. Build the pile in layers: start with 8 to 10 inches of leaves, grass, or plant trimmings, water until moist but not soggy, then add a nitrogen source. The University of Minnesota Extension recommends sprinkling one-third to one-half cup of a high-nitrogen lawn fertilizer without herbicide per 25 square feet of surface area, or using a 2-inch layer of livestock manure if available. You can add a 1-inch layer of soil or finished compost to introduce more microbes, though most yard waste already contains enough. Repeat these layers until the pile is about 5 feet tall, watering each time.

An active compost pile heats up to between 130°F and 160°F, according to the University of Minnesota Extension. As the center cools, turn the pile once or twice a month to speed decomposition and reduce odors. Continue to water periodically to keep the material moist but not waterlogged. Purdue’s Mitchell notes that if the pile smells bad or feels soggy, add more browns. Turning also helps incorporate oxygen, which microorganisms need to thrive.

Lime is usually unnecessary. The University of Minnesota Extension states that finished compost tends to be slightly alkaline, and adding lime during decomposition can make it too alkaline. If your pile contains a lot of acidic materials like pine needles or fruit waste, you can add no more than one cup of lime per 25 cubic feet of material, but excessive lime can cause nitrogen loss.

When Is Compost Ready and How to Use It

A well-managed pile will be ready in two to four months during the warm season, while an untended pile may take a year or more, according to the University of Minnesota Extension. Finished compost will be about half its original height and have a pleasant, earthy smell. Purdue’s Mitchell says the material should resemble uniform potting soil, but it should be used as a soil amendment, not a standalone potting mix.

Incorporate compost into garden beds to improve soil texture and nutrient availability. Clemson Cooperative Extension recommends starting with 25 percent organic matter by volume, or about 2 inches of compost worked into the top 6 inches of soil. Avoid incorporating more than 50 percent organic matter, as too much can negatively affect plant growth. Compost also makes an effective mulch to suppress weeds and retain moisture. If you use composted manure, Clemson Extension advises that fresh manures should be applied at least 90 days before harvest for vegetables whose edible parts do not touch the soil, and 120 days for those that do. Properly composted materials that have reached an internal temperature of 140°F are less likely to contain weed seeds or pathogens.

Before amending your soil, consider a simple jar test to evaluate its texture, as suggested by Clemson Extension. A soil test can also reveal nutrient levels and pH. Learn more about soil testing in our Soil Testing guide and about different soil types in Soil Types. For general garden preparation, see Gardening Basics.

A Note on Lawn Clippings

Grass clippings are a valuable source of nitrogen for the compost pile, but the University of Minnesota Extension points out that you often don’t need to bag them at all. Clippings that are an inch or less in length can be left on the lawn, where they decompose quickly and return nutrients to the soil, reducing the need for nitrogen fertilizer. This practice does not contribute to thatch buildup. Remove longer clippings, however, because they can shade or smother the grass. If you do collect clippings, mix them with dry materials like leaves in the compost pile to prevent matting and odors. Do not use clippings as mulch if the lawn was recently treated with an herbicide; always check the product label for guidance. For more on mowing practices, see Lawn Mowing.

Frequently asked questions

How long does it take to make compost?

The University of Minnesota Extension says a well-managed pile can be ready in two to four months during the warm season. If you do not turn or water the pile, it may take a year or more to fully decompose.

Can I compost pet waste?

No. Both the University of Minnesota Extension and Purdue University advise against composting pet feces because of the risk of disease transmission. Manure from herbivores like chickens or cows is acceptable, but waste from meat-eating animals should be kept out.

Why does my compost pile smell bad?

A foul odor usually means the pile is too wet or lacks oxygen. The University of Minnesota Extension recommends turning the pile to introduce air and adding dry brown materials. Purdue’s Mitchell also suggests adding more browns if the pile becomes soggy or smelly.

Because climate and soil conditions vary, check with your state’s cooperative extension service for local recommendations on composting timing and plant choices. For more detailed guides on composting, soil health, and starting a garden, visit our Composting section.

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