Composting at Home

Learn how to compost at home.

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Getting Started

In the City of St. Louis, about 30% (by weight) of what households throw away is food and yard waste.  Disposing of that material causes pollution from fuel consumed by collection trucks, costs money to bury in a landfill, and creates the greenhouse gas methane as it anaerobically decomposes in a landfill.  Residents can reduce the impact of organic (once-living) waste by composting at home.

Composting is the decomposition of organic materials. Starting a compost pile at home requires some effort, but most of the work is done by tiny living organisms called decomposers. If you keep the decomposers happy, your home composting system will supply you with nutrient rich compost and should not attract and pests or have an unpleasant odor.

Composting Links

Composting and Biodegradable Products
Composting Resources
Composting with Worms
Organics Recycling - Composting

How Does It Work?

Within your compost pile is a world of living organisms eating away at your organic waste. They include insects, fungi, mold, and bacteria. As they digest the materials in your bin, they produce heat. The heat generated by these organisms can reach 150 degrees Fahrenheit, which is hot enough to kill weed seeds or pathogens that make their way into your pile.

The decomposers living in a healthy compost pile require food (organic matter), air, and water. Too much or too little of any of those ingredients can get your pile off kilter. But, getting your compost back into equilibrium is not difficult if you know what to look and smell for.

Where do you get decomposers? Don't worry, all the decomposers you need are already living in your soil. If your compost pile is sitting directly on the ground, they will migrate up into your bin in search of food. If you opt for an enclosed bin, simply grab a handful of dirt and toss it in with your compost.

What To Compost

All living things are organic and are therefore compostable. However, a home composting system does not get hot enough to properly and safely decompose some organic materials. These non-desirable items are listed as "Non-Compostables" in the chart below. Notice that of the materials listed as "Compostables," some are listed as "Greens" and some are listed as "Browns." Greens are nitrogen rich materials and are usually green and moist. They are the equivalent of protein for the decomposers. Browns are carbon rich and are usually brown and dry. They are the equivalent of carbohydrates for the decomposters.

A healthy compost pile needs a balanced diet of greens and browns. A ratio of 2 parts browns and 1 part greens is a good starting point. You can adjust your ratio as needed. If the pile seems to be decomposing slowly, you may have too much carbon and you should mix in some greens. If the pile smells like ammonia, it has too much nitrogen and you should mix in some browns.

COMPOSTABLE GREENS
 		COMPOSTABLE BROWNS
 		NON-COMPOSTABLES
Coffee grounds
 Bread Anything treated with pesticides
Eggshells Bark Black walnut
Fresh garden clippings
 Dried Leaves
 Blood, bones, meat, fish
Fresh grass clippings
 Dried grass
 Cat or dog feces
Fresh leaves
 Dried plant and tree trimmings
 Dairy products
Fruit and vegetable scraps and peelings
 Pasta Fat, grease, oil
Produce (i.e., fruits, vegetables)
 Pine needles (sparingly)
 Glossy paper
  Sawdust (sparingly)
 Hollies, Oaks, Southern Magnolias
  Straw Weeds (creeping or seed-bearing)
  Wood ashes (sparingly)
 Vacuum cleaner dust (lead paint)

Compost Bin Basics

Choosing A Bin

There are a variety of compost bins available on the market. There are also many do-it-yourself instructions available on the Internet. Some people even choose to compost with no bin at all. The choice is yours. However, keep in mind the optimal size for a compost bin or pile is 3 feet tall x 3 feet wide x 3 feet deep. That is the size that will retain heat while still allowing air circulation through the pile.

Where To Place Your Compost Pile

Whether using a compost bin or building a free-standing pile, you'll want to place your compost in an area that is easily accessible. Consider the proximity to the source of your organic materials (e.g., garden, lawn, kitchen). How far will you want to walk to empty your kitchen scraps into the compost pile? Is it accessible by wheelbarrow or garden cart? Is there room for you to maneuver and turn your compost? Will your garden hose reach the pile?

Keep your bin or pile in a shady area if possible. Your compost will need to maintain moisture in order for the decomposers to break down your organics. If placed in the sun, your compost will dry out faster and require watering. Finally, try to avoid placing the bin or pile near objects that impede air circulation. The decomposers working in your compost pile need oxygen.

Air

Aerobic (oxygen dependant) decomposers are ideal for home composting. They efficiently break down your organic waste into clean, earthy smelling compost. But, if your pile doesn't have enough oxygen, the aerobic decomposers go on strike. You will know this is happening if your pile is no longer producing heat. To prevent this, periodically aerate your compost. Bins or piles can be turned using a pitchfork, compost aerator, or other turning tools. Tumbling bins simply need to be rotated.

Water

Every living thing needs water, and that includes the workhorses of your compost pile. Aerobic decomposers prefer the moisture level of your compost to be about that of a well wrung-out sponge. If you grabbed a handful of compost, you should be able to squeeze out a few drops of water. Too little water will halt the decomposition process. If your compost pile becomes too dry, water it with a garden hose or leave it uncovered in the rain. Too much water will drown the aerobic decomposers and allow anaerobic decomposers to move in. While anaerobic decomposers will eventually break down your organic waste, they will also produce a rotten-egg smell. To resolve this problem, simply add more browns to absorb the excess moisture.

Time

If you actively manage your compost pile, maintaining the proper ratio of greens to browns, checking the moisture level, and aerating frequently, you will be able to produce finished compost in a minimum of six weeks. If you passively manage your compost pile, tossing in whatever you have on hand, paying little attention to the moisture level, and rarely aerate the pile, it may take up to a year or more to produce finished compost. There's no wrong way to compost. All organic materials will decompose eventually. It's up to you how much time and effort you want to put into it and how quickly you want the finished compost.

You will know that your compost is finished when its volume has reduced by about half, it has cooled off, and the organic waste is indistinguishable.

Trouble Shooting

PROBLEM CAUSE SOLUTION
Decomposing slowly
 Too much carbon
 Add greens
Decomposing slowly
 Too dry
 Add greens and/or water
Decomposing slowly
 Not enough oxygen
 Aerate
Pests Non-compostables in pile
 Remove non-compostables
Pests Food waste left uncovered
 Bury and cover food waste
Smells like ammonia
 Too much nitrogen
 Add browns
Smells like rotten eggs
 Too wet
 Add







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