What to Compost vs. What Not to Compost

Composting is a great habit, both for your home and the environment. Food scraps and yard waste make up more than 30 percent of what we throw away on a yearly basis, and much of that "garbage" can be put to better use as compost.

Knowing what's safe to throw in your composting bin (and what should stay out) can be confusing. Read on to learn all about what makes up a good compost combination, what you can include from your home, and what you should dispose of as traditional trash.

What Is Compost?

At its most basic, composting is the natural breaking down of organic materials into valuable fertilizer. In order to be successful, composting experts recommend that all "batches" of compost contain three ingredients: brown matter, green matter, and water.

Brown matter: includes materials such as twigs, branches, paper, and cardboard—basically anything dry or woody. In most cases, items in the "brown" category will be naturally brown, but there are certainly exceptions to that rule. Brown matter contains carbon, which provides energy for the beneficial microbes in the compost.

Green matter: refers to natural waste products that most likely were recently growing and have some semblance of moisture. This could include things like fruit and vegetable waste and grass clippings, but materials such as coffee grounds are also considered to be green matter.

In most cases, your green items will provide your compost mixture with the adequate amount of moisture needed for proper breakdown, but it may be necessary to add some water during dry weather so the compost doesn't dry out. Some experts recommend about a 2:1 ratio of brown to green compost, although opinions on this can vary. If you find your mixture is beginning to smell, you can add more brown material.

List of Things You Should and Should Not Compost

What Not to Compost

While the opportunities for items you can compost are (almost) endless, there are several types of things you should leave out of your compost pile if you want to have a successful and safe fertilizer in the end (beyond the obvious, like plastic products).

Meat and Fish

One of the biggest categories is animal byproducts: meat, fish, egg, dairy, and poultry products. You may think animal byproducts such as these are alright to compost, but they can actually breed bacteria, cause odor problems, and result in pests, like rats.

Dairy, Oils, and Fats

Dairy products like milk, sour cream, yogurt, cheese, and butter should not be composted because they also attract pests. The same goes for oils and fats. Processed foods that contain a lot of dairy or fat should also be left out.

Coal and Charcoal Ash

If your end goal with composting is to produce a useable fertilizer for your plants, you should also carefully consider what you compost and the potential harm it can do to your plants. Items like coal or charcoal ash could contain substances harmful to plants, which could result in your vegetable garden dying by the time you get around to using your fertilizer.

Debris From Black Walnut Trees

The same goes for leaves or twigs from black walnut trees—they contain the toxin juglone, which is known to harm many plants, including peppers, potatoes, and tomatoes.

 Plants or Wood Treated With Pesticides 

Trimmings from plants that have been previously treated with pesticides should also be avoided.

Diseased or Insect-Infested Plants

A compost pile has to reach 141 to 145 degrees F for at least several days in order to kill fungi and bacteria, which isn't feasible for a home compost bin, meaning pests and pathogens can survive.

Weeds that Have Gone to Seed

These can also survive unless a high temperature is achieved, and you likely don't want to sow weeds on your next crop.

Dog or Cat Excrement

Waste from pets can make compost hazardous with bacteria and parasites that can cause human diseases. For instance, cat feces and litter carry the organism that results in toxoplasmosis. This disease is of particular concern to pregnant people as it can seriously injure an unborn child.

On the same note, homes that have pets or young children roaming around should also carefully consider what they compost, lest a curious dog or toddler finds their way into the compost pile. While most items in your compost bin won't cause harm, items that can contain parasites or other bacteria may be harmful.

Convenience Is Key

When it comes to finding success while composting, the "best" things to compost are the ones you're going to remember to compost. Maybe that means you'll find great success with composting your cooking scraps after each meal but not much with other items around the house—and that's fine! Even small steps can add up to a big impact.

Do your best to maintain a good ratio of brown to green material and trust that your efforts will be worth it in the long run.