Composting is a fantastic way to reduce waste and enrich your garden soil. However, not everything belongs in your compost bin. Three common items you absolutely shouldn’t compost are meat and dairy products, diseased plants, and pet waste. These can attract pests, spread pathogens, and introduce unwanted elements into your finished compost.

Why Knowing What NOT to Compost Matters

Composting is a natural process that breaks down organic materials. When done correctly, it yields nutrient-rich compost for your garden. But adding the wrong items can disrupt this process. It can lead to unpleasant odors, attract unwanted pests like rodents and flies, and even introduce harmful bacteria or diseases into your garden. Understanding what to exclude is just as crucial as knowing what to include.

The Risks of Composting Certain Items

• Attracting Pests: Meat, dairy, and oily foods can attract larger animals and create foul odors.
• Spreading Diseases: Diseased plants can harbor pathogens that survive the composting process. These can then infect healthy plants in your garden.
• Pathogen Concerns: Pet waste, especially from cats and dogs, can contain parasites and bacteria harmful to humans.

Three Things You Absolutely Shouldn’t Compost

Let’s dive into the specifics of what to keep out of your compost bin. These items pose the biggest risks to your composting efforts and garden health.

1. Meat, Dairy, and Oily Foods

While technically organic, meat scraps, bones, cheese, milk, and cooking oils are best avoided in a home compost system. These items decompose slowly and can create a strong, unpleasant odor. This smell is a powerful attractant for rodents, flies, and other unwanted pests.

Furthermore, these materials can harbor harmful bacteria like Salmonella and E. coli. If your compost pile doesn’t reach sufficiently high temperatures to kill these pathogens, they could remain in the finished compost. This poses a risk if you use the compost on edible plants.

Examples to Avoid:

• Leftover chicken bones
• Greasy pizza boxes
• Spoiled milk or yogurt
• Butter and cooking oils

2. Diseased Plants and Weeds with Seeds

It’s tempting to toss all your garden waste into the compost. However, plants suffering from fungal diseases, viral infections, or bacterial blights should be disposed of separately. Many common plant diseases can survive in a typical home compost pile. The heat generated may not be enough to kill the pathogens.

When you add this contaminated compost back to your garden, you risk reintroducing and spreading these diseases to your healthy plants. Similarly, weeds that have gone to seed should be avoided. The composting process might not kill all the seeds, leading to a weedier garden next season.

Best Practices:

• Bag diseased plants and put them in the trash.
• Research local guidelines for disposing of diseased plant material.
• Remove weeds before they go to seed. If you must compost weeds, do so only if you have a very hot compost system.

3. Pet Waste (Dog and Cat Feces)

Composting dog and cat feces is generally not recommended for home gardeners. These animals are carnivores, and their waste can contain a variety of harmful pathogens. These include Toxoplasma gondii, E. coli, Salmonella, and various parasites.

These pathogens can survive in compost for extended periods. If the compost is used on vegetable gardens, there’s a significant risk of contaminating produce and exposing humans to serious illness. While some industrial composting facilities can safely process pet waste, home compost piles rarely reach the necessary temperatures.

Safer Alternatives:

• Dispose of pet waste in sealed plastic bags in the trash.
• Check with your local municipality for specific pet waste disposal regulations.
• Consider specialized pet waste composting systems if available and recommended for your climate.

What About Other Potentially Problematic Items?

While the above are the top three, a few other items warrant caution. These include chemically treated wood, glossy or coated paper, and large amounts of citrus or onions.

Chemically Treated Wood

Wood treated with chemicals, such as pressure-treated lumber or painted wood, should never be composted. These chemicals can leach into your compost, potentially harming your plants and contaminating your soil.

Glossy or Coated Paper

While plain paper and cardboard are excellent compost additions, glossy magazines, coated paper, and heavily inked materials are best avoided. The coatings and inks may contain plastics or heavy metals that don’t break down well.

Large Amounts of Citrus or Onions

Small amounts of citrus peels and onion scraps are fine. However, adding excessive quantities can make your compost pile too acidic. This can slow down the decomposition process and deter beneficial microorganisms.

People Also Ask

### Can I compost meat scraps if I have a hot compost bin?

While a hot compost bin (reaching temperatures of 130-160°F or 55-70°C) can kill some pathogens, it’s still generally advised against composting meat scraps in a home setting. Achieving and maintaining these high temperatures consistently is difficult for many home composters. The risk of attracting pests and potential pathogen survival remains a concern.

### Is it safe to compost diseased tomato plants?

No, it is not safe to compost diseased tomato plants, especially if they show signs of blight, wilts, or other common tomato ailments. These pathogens can easily survive in a home compost pile and spread back to your garden, infecting future crops. It’s best to dispose of them in the trash or through municipal green waste programs that handle diseased material.

### What about composting yard waste from a neighbor?

Composting yard waste from a neighbor can be a great way to get more material, but exercise caution. Ensure their yard waste doesn’t contain any diseased plants, invasive weeds with seeds, or chemical treatments like herbicides or pesticides. If you’re unsure, it’s safer to decline or carefully inspect the material before adding it to your compost.

Making the Most of Your Compost

By avoiding these common pitfalls, you can ensure your composting efforts are successful. You’ll create a valuable soil amendment without introducing harmful elements. Remember, healthy compost starts with healthy ingredients.

Next Steps:

• Review our guide on "What to Compost" to maximize your bin’s contents.
• Consider investing in a compost thermometer to monitor pile temperatures.
• Share your composting successes and challenges in the comments below!