Composting is a fantastic way to reduce waste, enrich your garden, and minimize your environmental footprint. However, not all food scraps are created equal. Throwing the wrong items into your compost bin can lead to unpleasant odors, slow down decomposition, attract pests, and even create harmful conditions for your plants. Understanding which foods are compostable and which are not is crucial for successful composting.
The Golden Rule: When in Doubt, Leave it Out
The cardinal rule of composting is: when you’re unsure, it’s best to err on the side of caution and leave the questionable item out. A little extra effort in the short term can save you a lot of headaches (and smells!) in the long run. A well-maintained compost pile thrives on balance – a proper mix of “greens” (nitrogen-rich materials) and “browns” (carbon-rich materials). Introducing incompatible items can disrupt this balance and hinder the decomposition process.
Animal Products: A Composting No-No
Perhaps the most widely recognized composting taboo revolves around animal products. Meat, dairy, and bones are generally discouraged from being added to home compost systems.
Meat and Fish
Meat scraps, including cooked and uncooked meat, poultry, and fish, should not be composted in most backyard setups. These materials decompose slowly and unevenly, often emitting foul odors that can attract unwanted attention from rodents, flies, and other pests. Moreover, they can harbor harmful bacteria, such as salmonella and E. coli, which may not be completely destroyed during the composting process, especially if the pile doesn’t reach sufficiently high temperatures.
Large bones are exceptionally slow to break down and can remain intact for years. Smaller bones, such as those from fish or chicken, will eventually decompose, but the process is still slow and can attract pests. The risk outweighs the benefit.
Dairy Products
Similar to meat, dairy products like milk, cheese, yogurt, and cream cheese pose challenges to home composting. The fats in dairy can create anaerobic conditions within the compost pile, leading to unpleasant smells and hindering the decomposition process. Dairy can also attract pests, further disrupting the composting ecosystem.
Eggs: Proceed with Caution
Eggshells, on the other hand, are generally considered acceptable for composting. They are a good source of calcium and other minerals that can benefit the soil. However, eggshells should be rinsed and crushed before adding them to the compost pile. The egg white and yolk remnants can attract pests, so thorough rinsing is essential.
Whole eggs, or even large amounts of egg whites or yolks, should be avoided for the same reasons as other dairy products: potential for unpleasant odors and pest attraction.
Fats, Oils, and Greases: Slippery Slope to Composting Disaster
Fats, oils, and greases (FOG) are another category of food waste that should be kept out of your compost bin. This includes cooking oil, lard, butter, margarine, and even oily salad dressings.
Why FOG is a Problem
Fats, oils, and greases are hydrophobic, meaning they repel water. This can disrupt the moisture balance in your compost pile, making it difficult for microorganisms to break down organic matter. They can also coat other materials, preventing them from properly decomposing. Furthermore, FOG can attract pests and create unpleasant odors.
In addition, FOG can bind together and form clumps that impede airflow within the compost pile, leading to anaerobic conditions. Anaerobic decomposition produces methane, a potent greenhouse gas, and other undesirable byproducts.
Nut Butters: A Surprising Culprit
While seemingly innocuous, nut butters, especially those containing added oils and sugars, can also contribute to the problems associated with FOG. They are high in fat and can attract pests. Small amounts of natural nut butter residue on a spoon are unlikely to cause significant issues, but large quantities should be avoided.
Processed Foods: A Complex Composting Question
Processed foods present a more nuanced composting challenge. While some processed food scraps can be composted, others should be avoided. The key is to consider the ingredients.
Foods High in Salt, Sugar, or Oil
Processed foods that are high in salt, sugar, or oil should generally be excluded from the compost pile. Excess salt can inhibit the growth of beneficial microorganisms, slowing down decomposition. Sugar can attract pests and disrupt the carbon-to-nitrogen ratio. As mentioned earlier, oil creates anaerobic conditions and attracts pests.
This category includes items like heavily salted snacks, sugary cereals, oily baked goods, and processed meats with high sodium content.
Foods Containing Preservatives
Many processed foods contain preservatives designed to inhibit microbial growth and extend shelf life. These preservatives can also inhibit the activity of beneficial microorganisms in your compost pile, slowing down the decomposition process.
Breads and Grains: A Conditional “Maybe”
Breads and grains, in small amounts, can be composted. However, they should be added sparingly and mixed thoroughly with other materials. Large quantities of bread can become compacted and matted, hindering airflow and creating anaerobic conditions. Moldy bread is fine to compost, but be aware that the spores may spread. Avoid composting breads with high oil or sugar content, such as donuts or pastries.
Plants Treated with Pesticides or Herbicides
While composting garden waste is generally encouraged, you should avoid composting plants that have been treated with pesticides or herbicides. These chemicals can persist in the compost and potentially harm beneficial soil organisms or contaminate your garden soil when you use the compost.
Identifying Treated Plants
It can be difficult to determine whether a plant has been treated with chemicals unless you grew it yourself or know its history. If you are unsure, it is best to err on the side of caution and dispose of the plant waste through other means.
Diseased Plants: Another Composting Concern
Similarly, avoid composting plants that are infected with diseases. The composting process may not always kill off all pathogens, and you risk spreading the disease when you use the compost in your garden.
Persistent Weeds and Invasive Species
Composting weeds can be a great way to dispose of them, but it’s crucial to ensure that the composting process is hot enough to kill the weed seeds. Many home compost piles do not reach sufficient temperatures to effectively kill all weed seeds.
Composting invasive species is particularly risky. These plants are highly adaptable and can often survive even harsh conditions. If the compost pile doesn’t reach high enough temperatures, the invasive species can spread when you use the compost. It’s best to avoid composting invasive species altogether.
Black Walnut Trees and their Toxic Secretions
Black walnut trees produce a substance called juglone, which is toxic to many plants, including tomatoes, peppers, and eggplants. Avoid composting leaves, twigs, and hulls from black walnut trees, as the juglone can persist in the compost and harm sensitive plants in your garden.
Pet Waste: A Definite Discard
Pet waste, including dog and cat feces, should never be composted in home compost systems. Pet waste can contain harmful pathogens, such as bacteria, viruses, and parasites, that can pose a health risk to humans. These pathogens may not be completely destroyed during the composting process, especially if the pile doesn’t reach sufficiently high temperatures.
Additionally, pet waste can attract pests and create unpleasant odors. It is best to dispose of pet waste in a sealed bag and throw it away in the trash.
Non-Biodegradable Materials: An Obvious Exclusion
This should be self-evident, but it’s worth mentioning that non-biodegradable materials should never be added to the compost pile. This includes plastic, metal, glass, and synthetic fabrics. These materials will not break down and will contaminate your compost.
“Biodegradable” Plastics: Proceed with Extreme Caution
While some plastics are labeled as “biodegradable” or “compostable,” these terms can be misleading. Many of these plastics require specific industrial composting conditions to break down, which are not typically found in home compost systems. Adding these plastics to your home compost pile can result in them breaking down into smaller pieces of plastic, which can still contaminate your soil.
Large Branches and Woody Material
While wood is a valuable “brown” material for composting, large branches and woody material should be chipped or shredded before being added to the pile. Large pieces of wood decompose very slowly and can take years to break down completely. Chipping or shredding the wood increases its surface area, allowing microorganisms to break it down more quickly.
Oily or Glossy Paper
While paper is a good source of carbon for your compost pile, you should avoid composting oily or glossy paper, such as magazines and coated cardboard. The coatings on these papers can contain harmful chemicals that can leach into your compost. Newspaper, plain cardboard, and paper towels (that haven’t been used with harsh chemicals) are generally safe to compost.
A Final Word on Responsible Composting
Composting is a valuable practice, but it’s essential to do it responsibly. By understanding which foods and materials should be excluded from the compost pile, you can ensure that your compost is healthy, beneficial, and safe to use in your garden. Remember, when in doubt, leave it out!
Why shouldn’t I compost meat, bones, or dairy products?
These items are significant no-nos in traditional backyard compost bins because they attract unwanted pests like rodents and flies. The decomposition process for animal products is also much slower and creates unpleasant odors that can bother your neighbors.
Furthermore, the high fat content in meat and dairy can disrupt the delicate balance of your compost pile. This imbalance can lead to anaerobic conditions (lack of oxygen), further exacerbating odor problems and slowing down the overall composting process. These anaerobic conditions can also foster the growth of harmful bacteria.
Are there any food scraps that could be harmful to my compost?
Yes, certain food scraps can introduce harmful substances to your compost. Oily or greasy foods are difficult to break down and can also attract pests, similar to meat and dairy. Additionally, diseased plants or those treated with pesticides should not be composted as the diseases and chemicals could persist in the compost and later contaminate your garden soil.
Another important consideration is avoiding composting black walnut tree debris. Black walnut trees contain juglone, a toxic substance that can inhibit the growth of many plants. Composting black walnut leaves, twigs, or husks can transfer this juglone into your compost, making it unsuitable for many gardening applications.
What about processed foods? Are they generally safe for composting?
Processed foods often contain high levels of fats, oils, salts, and preservatives that hinder the composting process. These ingredients can slow down decomposition, attract pests, and create unpleasant odors. The preservatives, in particular, are designed to inhibit microbial activity, which is essential for successful composting.
Furthermore, many processed foods contain animal products like dairy or meat-based ingredients, further exacerbating the problems discussed earlier. It’s generally best to avoid composting processed foods and stick to raw, unprocessed plant-based materials for optimal composting results.
Why shouldn’t I compost pet waste?
Pet waste, particularly from cats and dogs, can contain harmful pathogens, including bacteria, viruses, and parasites. These pathogens can survive the composting process, especially if your compost pile doesn’t reach high enough temperatures to kill them.
Using compost contaminated with pet waste in your vegetable garden can pose a serious health risk to you and your family. These pathogens can contaminate the produce and potentially cause illness if ingested. It is therefore advisable to avoid composting any pet waste and consider alternative disposal methods.
Can I compost citrus peels? I’ve heard conflicting opinions.
Citrus peels can be composted, but with caution. In small quantities, they are generally acceptable. However, large amounts of citrus peels contain high levels of limonene, which can be toxic to beneficial microorganisms in your compost pile. This can slow down the decomposition process.
Furthermore, citrus peels are waxy and can take longer to break down than other compostable materials. Chopping them into smaller pieces can help speed up the process. It’s best to add citrus peels sparingly and ensure they are well mixed with other compostable materials.
What about weeds? Can I compost them?
Composting weeds is possible, but you need to be careful about the types of weeds you’re adding to your pile. Weeds that have gone to seed should never be composted in a typical backyard composter. The seeds can survive the composting process and spread throughout your garden when you use the compost.
However, if you have a hot composting system that reaches high temperatures (130-160°F), you can compost many weeds, including those with seeds. The high heat will kill the seeds and prevent them from germinating. Make sure to monitor the temperature of your compost pile to ensure it stays hot enough for a sufficient amount of time.
Is composting cooked rice or pasta a good idea?
While cooked rice and pasta are technically biodegradable, they can present some challenges in a compost pile. Cooked grains tend to become a slimy mass as they decompose, which can create anaerobic conditions (lack of oxygen) within the compost. This can lead to unpleasant odors and slow down the composting process.
Furthermore, cooked rice and pasta can attract pests, such as rodents, especially if they contain sauces or oils. If you choose to compost cooked rice or pasta, do so in small quantities and ensure it is well mixed with other dry, bulky materials to maintain proper aeration and minimize pest attraction.