Learn what compost is, how to compost, what food scraps can and can't be composted and how to use it to enrich your garden soil.

Kelly Reilly
Updated April 20, 2020
Advertisement

Don't toss those food scraps–compost them! According to the U.S. Environmental Protection Agency, food waste accounts for almost 22 percent of all waste that goes into municipal landfills, more than any other single material in our everyday trash. Beyond keeping food waste out of landfills, composting has other benefits as well, turning food scraps and plant clippings into nutrient-rich soil. Some states and municipalities have moved to enact food waste bans in landfills and offer robust commercial programs that make it really easy for individuals to start doing it themselves.

But even if you don't have a commercial program available in your area, you can still do it at home. Doing it in your backyard isn't as complicated or messy as you might think. By combining a few simple ingredients in the right proportions, you can be on your way to reducing food waste and creating a soil conditioner that benefits both your garden and the planet. Learn more about what compost is and how to start doing it yourself.

What Is Compost?

Compost is decomposed organic matter. It requires five basic ingredients:

  1. Carbon-rich materials ("brown materials" or "browns"), such as leaves, straw, bark, paper, corn stalks, wood chips or sawdust
  2. Nitrogen-rich materials ("green materials" or "greens"), such as grass clippings, vegetable scraps or coffee grounds
  3. Water
  4. Oxygen
  5. Microorganisms, such as bacteria, molds and fungi

Microorganisms, with the right amount of water and oxygen, break down carbon and nitrogen sources to create a final product that helps plants retain water and nutrients, and improves drainage and soil structure. Plus, turning yard and food waste into fertilizer can greatly reduce your landfill contribution.

Types of Composting

There are three types of composting.

Aerobic The aerobic method relies on mixing oxygen into the compostable materials to raise the temperature and help break down the material. This requires turning (or mixing) the materials every so often to give it exposure to oxygen.

Anaerobic The anaerobic method is the easiest way to compost, but it's also very stinky and slow. It involves piling the greens and browns and letting nature handle the decomposition process unaided.

Vermicomposting Vermicomposting or vermiculture which uses a worm composter for the decomposition process. That means instead of letting the organic materials break down naturally, worms eat it to produce a richer finished product.

To keep it simple, this guide is for the aerobic method.

How to Compost

Step 1

Add kitchen scraps and organic matter to your bin as needed, with a good mix of greens and browns. You should aim for a browns to greens ratio of 25:1 to 40:1. Although microorganisms are available for purchase, you probably won't need them because they are almost always naturally present in the carbon and nitrogen sources.

Step 2

Keep the pile moist but not too wet, as this will hamper decomposition. Add sawdust to dry it or water to moisten it as needed.

Step 3

Turn the pile with a rake or pitchfork regularly. Turning the compost helps promote oxygen flow and releases the heat that builds during decomposition-aim for a temperature between 90° and 140°F.

What Can Be Composted?

Getty Images

Any organic matter will decompose eventually, but for backyard composting, you want to use items that will decompose relatively quickly and that won't attract animals.

  • Vegetable & fruit scraps
  • Coffee grounds & filters
  • Eggshells
  • Tea & tea bags
  • Grass clippings
  • Leaves
  • Shredded newspaper
  • Soiled cardboard, such as pizza boxes, ripped into small pieces

These items can only be processed in commercial facilities (not in your backyard):

  • All food scraps, including animal products and bones
  • Certified compostable products such as cups, utensils and takeout containers (look for BPI-Certified on the label)

What Can't Be Composted?

While composting is a great way to reduce waste, some items will do more harm than good. Avoid placing these in your backyard pile:

  • Animal products such as dairy, bones and meat, which can attract pests (can be composted commercially)
  • Oily foods such as mayonnaise, peanut butter, salad dressing or vegetable oils, which are difficult to decompose (can be composted commercially)
  • Dog, cat and human waste, which can contain harmful pathogens
  • Pesticide-treated yard waste, whose chemicals aren't broken down during the decomposition process
  • Commercially grown cut flowers, which often contain dyes and chemicals
  • Weeds and their roots, which can grow in the pile and spread wherever you place the compost
  • Diseased plant material, which can spread the disease to nearby plants
  • Bio-plastic products that are labeled biodegradable

How to Use Compost

Compost is ready when the pile no longer emits heat, is dark in color, and crumbles easily. At a minimum, it will take several months to form. Using smaller pieces of carbon and nitrogen sources, ensuring consistent moisture, and turning the pile regularly can help speed up the process. Avoid using unfinished compost on your garden, as it can actually be toxic to plants.

  • Mix compost into the top several inches of soil of your garden.
  • Use as mulch around trees and shrubs.
  • Use as a top-dressing for lawns.
  • Use as a substitute for part of the soil in your container garden.

Do You Need to Use a Compost Bin?

You could just start a heap at the back of your property, but using a bin helps to retain heat and moisture, which will help with decomposition. It will also keep critters away from your food scraps. Compost bins vary widely in size, material and cost. You can purchase or build a permanent holding unit -or if you're just getting started, drilling holes 4 to 6 inches apart around a simple garbage can will suffice. Place your bin in a low-traffic area of your lawn where it will be protected from high winds.

Commercial Composting Services

If you're not interested in a DIY compost pile but still want to help reduce landfill waste, some municipalities offer drop-off or curbside composting. Simply place your compostables in a separate bin for pickup or drop-off along with your garbage and recycling. Some cities even offer residents the opportunity to pick up the completed DIY fertilizer for use in their gardens. Contact your municipality to see if such services exist, or check out this list for places in your state that accept compost.

Related: