What to Compost vs. What Not to Compost Guide

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. When disposed of through traditional trash methods, these materials end up in landfills, where they take up room and release methane (a greenhouse gas). However, when collected and cared for through composting methods, these organic materials can break down properly, eventually being added to the soil in your yard to help your plants grow better.

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. When it comes to composting, 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 also 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.

What to Compost

If you're trying to figure out what around your home is fair game for composting, we have good news—a ton of it probably is! From coffee grounds and used napkins to dinner scraps and paper shopping bags, there's a long list of things you can compost.

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.

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). 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.

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. The same goes for leaves or twigs from black walnut trees—they contain the toxin juglone, which is known to harm many plants. Trimmings from plants that have been previously treated with pesticides should also be avoided.

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, things like pet waste or spoiled meat can contain parasites or other bacteria that can be harmful.

Items to Think Twice About Composting

There are some items that, while they can technically be composted, are better tossed in the garbage due to the risk of disease or the smell compost emits. If you live in an area that is especially prone to wildlife, you may want to steer clear of composting anything that is particularly delicious to bears, raccoons, and wolves, unless you have a very secure compost bin. These types of animals are attracted by certain food scraps, and bears in particular tend to be attracted to fragrant and sugary food, like baked goods and typical "junk" foods.

Likewise, too much of a good thing can also be an issue. A bit of citrus is fine, but too much acidity in your compost mixture (like scraps from oranges, tomatoes, lemons, and more) can actually begin to harm the beneficial bacteria in your mixture. The same goes for onion and garlic scraps, which can actually kill worms and other microorganisms that are essential for breaking down organic matter.

A Definitive List of What Should and Shouldn't Be in Your Compost

Like most new habits, composting (and learning what can and can't be added to your pile) will take a bit of practice. Keep the chart below on hand for the first few months to teach yourself what to toss in the trash and what to turn into "black gold" through composting.