Composting is a fantastic way to reduce waste, enrich your garden soil, and contribute to a more sustainable lifestyle. However, not everything decomposes beneficially. Throwing the wrong items into your compost bin can lead to foul odors, attract pests, and even introduce harmful pathogens into your garden. While composting is generally forgiving, understanding what not to compost is just as important as knowing what to compost. Let’s delve into the three crucial categories of items that should be strictly avoided in your compost pile.
Meat, Dairy, and Oily Foods: A Recipe for Disaster
Introducing meat, dairy products, and oily foods into your compost system is a common mistake that many novice composters make. These items are often rich in fats and proteins, which while seemingly organic, break down differently than plant-based materials. The consequences of composting these materials can be quite unpleasant.
The Problems with Composting Animal Products
Animal products, including meat scraps (cooked or raw), bones, and even seemingly harmless items like cheese and yogurt, decompose anaerobically. This means they break down in the absence of oxygen. This anaerobic decomposition process is what creates the foul, rotten egg smell often associated with poorly managed compost piles.
Moreover, meat and dairy are powerful attractants for unwanted guests. Rodents, flies, and other pests will be drawn to the smell, potentially turning your composting area into a breeding ground for these unwanted creatures. This defeats the purpose of a clean and efficient compost system and can lead to more significant pest control issues around your property.
Additionally, the decomposition of animal products can introduce harmful pathogens into the compost. These pathogens can survive the composting process, especially if the pile doesn’t reach sufficiently high temperatures. Using compost contaminated with these pathogens in your garden can then transfer the pathogens to your plants and, potentially, to you when you consume the produce.
Why Oil and Grease are Problematic
Oils and grease, whether from cooking or other sources, pose a different set of challenges. They don’t break down easily and can create a hydrophobic barrier within the compost pile. This barrier prevents water and air from circulating properly, hindering the decomposition process for all other materials.
Furthermore, oily residues can coat beneficial microorganisms, the workhorses of your compost system, inhibiting their activity. This slows down the overall composting process significantly, and can result in a slimy, smelly mess. It is important to remember that even small amounts of oil can have a negative impact, so it’s best to avoid any food scraps containing significant amounts of oil.
A Note on Eggshells
While eggshells are technically an animal product, they are an exception to the rule. Eggshells are primarily composed of calcium carbonate, which is beneficial for plants. They break down slowly, providing a slow-release source of calcium and also helping to improve soil structure. However, it is best to rinse them before composting and crush them well to speed up the decomposition process.
Diseased Plants and Invasive Weeds: Spreading Problems
Composting is a great way to recycle yard waste, but certain types of yard waste can introduce problems into your garden. Diseased plants and invasive weeds are two categories of yard waste that should never be added to your compost pile, unless you have a hot composting system.
The Danger of Diseased Plants
Diseased plants, even after they appear dead, can still harbor pathogens like fungal spores, bacteria, and viruses. Adding these plants to your compost pile can contaminate the entire batch, potentially spreading the disease back into your garden when you use the compost.
Certain diseases, such as tomato blight and powdery mildew, are particularly persistent and can survive even in a moderately hot compost pile. To avoid this risk, it’s best to avoid composting any plant material that shows signs of disease. Instead, these materials should be burned or disposed of in a way that prevents the spread of the disease.
The Spread of Invasive Weeds
Invasive weeds are another significant concern. These weeds are aggressive growers and can quickly take over your garden. Many invasive weeds have seeds or rhizomes that can survive the composting process, especially in cold composting systems.
When you use compost contaminated with these weed seeds, you are essentially spreading the weeds throughout your garden, making it even harder to control them. Even if some seeds are killed by the heat of the compost, a significant number can still survive, leading to a persistent weed problem. It is important to prevent these weeds from even making it to the compost by taking control of your yard before composting.
Hot Composting: A Possible Solution (With Caveats)
Hot composting, which involves maintaining a high temperature (130-160°F) in the compost pile for a sustained period, can kill many pathogens and weed seeds. However, achieving and maintaining these temperatures requires careful management and monitoring of the compost pile.
Unless you are confident in your ability to maintain consistently high temperatures throughout the entire compost pile, it’s best to avoid composting diseased plants and invasive weeds. The risk of spreading these problems is simply too high.
Pet Waste and Treated Wood: Toxic Additions
Pet waste and treated wood might seem like organic materials, but they pose significant health and environmental risks when added to a compost pile. It is essential to avoid these items to protect your health and the health of your garden.
The Health Risks of Pet Waste
Pet waste, particularly from cats and dogs, contains harmful bacteria, parasites, and pathogens that can survive the composting process. These pathogens can cause serious illnesses in humans, including E. coli, Salmonella, and Toxoplasmosis.
Using compost contaminated with pet waste in your garden can expose you to these pathogens, especially if you are growing edible plants. Even thorough washing of produce may not eliminate the risk completely. It’s simply not worth the risk to compost pet waste, especially if you plan to use the compost in a vegetable garden.
The Dangers of Treated Wood
Treated wood, which is commonly used for outdoor construction projects, contains chemicals that are designed to prevent rot and insect infestation. These chemicals, such as chromated copper arsenate (CCA) and other preservatives, are toxic to humans and plants.
When treated wood decomposes, these chemicals can leach into the compost, contaminating it and making it unsafe to use in your garden. The chemicals can also contaminate the soil and groundwater, posing long-term environmental risks. It is vital to never compost treated wood, even if it is broken down into small pieces.
Safe Alternatives for Pet Waste Disposal
Instead of composting pet waste, there are safer and more effective ways to dispose of it. One option is to bury it in a designated area of your yard away from vegetable gardens and water sources. Another option is to dispose of it in the trash. There are also pet waste composting systems designed specifically for this purpose, but these systems should be used with caution and the compost should never be used on edible plants.
Proper Disposal of Treated Wood
Treated wood should never be burned or composted. The best way to dispose of it is to take it to a local landfill or hazardous waste disposal facility. These facilities are equipped to handle treated wood safely and prevent the release of harmful chemicals into the environment.
Composting is a Rewarding Practice
Composting is a rewarding practice that can significantly benefit your garden and the environment. However, it is crucial to be mindful of what you put in your compost pile. Avoiding meat, dairy, oily foods, diseased plants, invasive weeds, pet waste, and treated wood will help you create a safe, healthy, and effective compost that will nourish your garden for years to come. By following these guidelines, you can ensure that your compost pile is a valuable resource rather than a source of problems.
Why shouldn’t I put meat scraps in my compost pile?
Meat scraps, including bones, fat, and skin, are a definite no-no for your compost pile. They attract unwanted pests like rodents, flies, and even larger animals, disrupting the composting process and potentially creating an unsanitary environment. The decomposition of meat is also a slow and often smelly process, which can negatively impact the overall odor and effectiveness of your compost.
Furthermore, meat scraps can introduce harmful pathogens into your compost, which may not be completely eliminated during the composting process, even at high temperatures. This can pose a risk to the health of your plants and, ultimately, to you if you use the contaminated compost on edible crops. Stick to plant-based materials for a healthy and safe compost.
Why is dairy not recommended for compost piles?
Dairy products, such as milk, cheese, yogurt, and butter, are best kept out of your compost pile due to similar reasons as meat. Like meat, dairy products attract unwanted pests and create unpleasant odors as they decompose. The high fat content in dairy can also create anaerobic conditions (lack of oxygen) within the pile, slowing down the decomposition process and leading to a foul smell.
Beyond the nuisance factor, dairy, like meat, can harbor harmful bacteria that may not be completely eradicated during composting, potentially contaminating the finished compost. Using compost containing these pathogens on your garden can pose risks, particularly for edible plants. It’s best to avoid dairy altogether to ensure a healthy and safe composting experience.
Why can’t I compost oily foods?
Oily foods, including cooking oils, greasy leftovers, and oily dressings, are not suitable for composting. The high fat content in these foods can disrupt the aeration of your compost pile, leading to anaerobic conditions. These conditions slow down decomposition and create a foul odor, making the composting process less efficient and unpleasant.
Furthermore, oily foods can attract pests like rodents and insects, turning your compost pile into an unwanted buffet. The oil can also coat beneficial microbes, hindering their ability to break down organic matter effectively. Keeping oily foods out of your compost will help maintain a balanced, healthy, and pest-free environment.
Why should I avoid putting pet waste in my compost pile?
Pet waste, including dog and cat feces, is a significant health hazard and should never be added to your compost pile. Pet waste often contains harmful pathogens, such as bacteria, viruses, and parasites, that can survive the composting process, even at high temperatures. These pathogens can contaminate your compost and pose a serious risk to human health if the compost is used in gardens, especially for edible plants.
Even composting systems designed for pet waste require specialized equipment and careful monitoring to ensure proper pathogen kill. A backyard compost pile is generally not equipped to handle this level of sanitation. It is always best to dispose of pet waste properly in a designated waste receptacle rather than risking contamination through composting.
What about diseased plants? Can I compost those?
Diseased plants are generally not recommended for composting, particularly if you have a standard backyard compost pile. The pathogens causing the plant disease, such as fungi, bacteria, or viruses, can survive the composting process if the pile doesn’t reach high enough temperatures consistently. This means that the finished compost could still contain the disease-causing agents.
Using compost contaminated with plant diseases can then spread the disease to other healthy plants in your garden. If you have a hot composting system that consistently reaches temperatures of 160°F (71°C) for several days, you might be able to compost some diseased plants, but it’s generally safer to dispose of them in the trash to avoid spreading the disease.
Why shouldn’t I put walnut leaves or black walnut tree debris in my compost?
Walnut leaves and other debris from black walnut trees contain juglone, a natural herbicide that inhibits the growth of many plants. This chemical can persist even after composting, potentially harming sensitive plants in your garden if you use the compost produced from these materials. Tomatoes, peppers, eggplant, and some other ornamentals are particularly susceptible to juglone.
Even thorough composting may not completely break down all of the juglone present. To avoid any potential harm to your plants, it’s best to avoid composting walnut leaves and debris altogether. Dispose of them separately, or consider burning them if local regulations allow. This will ensure that your compost remains safe for use on all of your plants.
Are chemically treated yard trimmings safe to compost?
Yard trimmings that have been treated with herbicides, pesticides, or other chemicals should generally be avoided for composting. These chemicals can persist through the composting process and contaminate the finished compost, potentially harming beneficial soil organisms and impacting the health of your plants. It’s difficult to know exactly how long these chemicals will remain active and what effects they might have.
Furthermore, these chemicals can leach into the soil and potentially contaminate groundwater. It’s always best to err on the side of caution and avoid composting chemically treated yard waste. If you’re unsure whether yard waste has been treated, it’s best to dispose of it in the trash to prevent potential environmental and health risks.