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Share to PinterestWhat Not to Add to Your Home Compost Pile

What Not to Add to Your Home Compost Pile

By Moira K McGhee
Share to PinterestWhat Not to Add to Your Home Compost Pile

As you scrape the remnants of your breakfast off the plate—eggshells and a few toast crumbs—you face a decision: toss it in the trash or start a compost pile? Every scrap you divert from the garbage can becomes part of a transformative process. Composting isn't just about waste reduction; it's a proactive step towards enriching your garden and participating in an eco-friendly cycle that benefits both the soil and the environment around you. Consider this as you decide where to discard your breakfast remnants.

Composting is nature's way of recycling organic materials, turning everyday waste into valuable food for your garden and putting it back into the soil instead of the landfill. But beware—the path to perfect compost isn’t as simple as throwing scraps into a pile.

Hidden hazards lurk in seemingly innocent waste, with some items better left out of your compost bin. From items that merely hinder the decomposition process to those that can turn your home heap toxic, understanding what not to include in your backyard composting pile is crucial.

If you’re considering starting a compost pile at home, this gardening feature shares a list of items you shouldn’t add to your heap and why these non-compostable items are harmful. It also touches on recognizing when your pile is fully composted and ready to enrich your soil.


Cultivating a thriving compost pile

Share to PinterestEarthworms in the soil on red shovel, compost box outdoors

A good rule of thumb to follow if you’re unsure whether you should put something in your compost pile – when in doubt, leave it out! Creating perfect compost is both a science and an art that requires attention to detail and patience. By being selective about what goes into your backyard composting bin, you avoid the pitfalls of adding non-beneficial, potentially harmful items and contribute to the creation of a nutrient-rich resource for your garden.

For more information and resources on how to compost effectively, check out your local extension office or community composting programs. These resources can provide valuable guidelines tailored to your local environment and conditions, helping you succeed in your composting endeavors.


Meat, fish, eggs and dairy products

Share to PinterestHands of young female holding piece of raw beef with spices over plate or bowl surrounded by kitchenware while standing by kitchen table

These food items can attract rats, flies and other pests and are likely to produce unpleasant odors as they decompose. They can also create an environment that promotes harmful bacteria, which can be hazardous if you use your compost on food crops.

Furthermore, the Environmental Protection Agency states that small backyard composting piles usually won’t get hot enough to break down these food products. However, empty eggshells are okay if you crush them first.


Treated wood or sawdust and particle board

Share to Pinteresta man standing on top of a pile of wood
Photo by Loren Biser on Unsplash

Wood that’s been treated or pressure treated and the sawdust from these woods contain harmful chemicals like creosote or arsenic. These chemicals can be toxic to plants, damaging your soil and beneficial microbes’ health. Furthermore, even if these chemicals weren’t harmful, they’re intended to repel moisture, the key ingredient to biodegradation.

Also, avoid composting wood that’s been painted. Particle board, plywood and medium-density fiberboard should also be left out of your composting pile because they often contain synthetic binding agents and chemicals that might not break down. These materials could also harm beneficial organisms in your compost.


Pet waste

Share to Pinteresta sign on a wooden fence that says please clean up after your pet
Photo by Todd Morris on Unsplash

Dogs are omnivorous, and cats are carnivorous, meaning their intestines can include a host of resilient parasites and pathogens. Their feces can also contain parasites, pathogens, bacteria and viruses that could harm humans, posing health risks if you use the compost in your food garden. Cat feces can be especially dangerous.

On the flip side, manure from animals that solely eat plants can be very beneficial in your compost. The exception is if the manure comes from a sick animal, which could pass harmful bacteria or viruses through its waste.


Colored or glossy paper

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Photo by Blair Fraser on Unsplash

The inks and chemicals used in colored and glossy paper may contain heavy metals that could contaminate your compost and eventually leach into the soil. These metals could be toxic and potentially harmful to plant life.

The coating on glossy paper, like those used in magazines, is often made from plastic, which isn’t compostable. However, newsprint and other non-colored, non-glossy paper are safe to use in your pile.


Diseased or Pest-Infested Plants

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Photo by Sebastian Marx on Unsplash

Plants with disease or pest problems or containing pesticides can transfer these problems back into your garden. Adding diseased or insect-infested plants can spread pathogens that survive the composting process and infect your garden when you use the compost.


Cooking oils

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Fat, grease, oil and lard can throw your compost’s moisture content out of balance. Moisture is critical to biodegradation. They can also reduce air circulation, the second key ingredient of a healthy compost pile. Cooking oils may also attract pests. These oils don’t just include liquids but also any items with oils on them, such as paper towels saturated with cooking oil or cardboard pizza boxes soaked with grease from the pizza.



Share to PinterestAn unrecognizable elderly senior woman outdoors on a terrace in on a sunny day in autumn, holding walnuts.

The fruits, shells, leaves and branches of walnut trees can be toxic to some plants when used in your compost because they contain juglone. This chemical has been known to damage potatoes, tomatoes, lilies and hydrangeas.


Coal or charcoal ash

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Photo by Philipp Kämmerer on Unsplash

Ashes produced from coal or charcoal can contain heavy metals that could be toxic to plants and leach into water supplies. They can also alter the pH in your compost, potentially rendering the soil less suitable for plant growth. Wood ash is safe to mix in your compost pile, but coal ashes and charcoal from grills aren’t safe.


Synthetic chemicals (pesticides or fertilizers)

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The residual chemicals on plants used to kill insects or control diseases can kill beneficial organizations, helping break down waste in your compost. They could also enter the food chain if you use compost that includes synthetic pesticides and fertilizers in your vegetable garden.


Plastic, glass and metal

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Photo by CHUTTERSNAP on Unsplash

These inorganic materials won’t break down and will contaminate your compost, making it unsuitable for use in your garden. These items also pose a potential hazard to wildlife and people working in the garden.


Dryer lint or vacuum cleaner contents

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Photo by Douglas Monterrosa on Unsplash

While you may not be able to see it, most textiles are either entirely made from synthetic fibers or a combination of synthetic and organic fibers. Synthetic fibers commonly derived from petroleum include nylon, rayon, polyester and elastane. Drying clothes can potentially introduce these fibers to the lint.

When you dry clothing or other items made from synthetic materials, those fibers end up in your dryer lint. Likewise, the fibers from carpets constantly shed, meaning you pick up these synthetic fibers and tiny pieces of plastic when you vacuum. Thus, neither dryer lint nor vacuum dust should be added because they’re non-biodegradable and introduce microplastics into your composting.



Share to Pinterestwhite cigarette stick on white wall
Photo by Andres Siimon on Unsplash

Straight tobacco is compostable, but cigarettes contain much more than tobacco. Cigarettes contain certain chemicals shown to inhibit plant growth. The tiny plastic particles in cigarette filters make it so they won’t break down.


Biodegradable plastics

Share to PinterestSorting Plastic Waste at Recycling Centers for Environmental Preservation and Resource Recovery

You switched to biodegradable and compostable plastics to be green and do your part to help support the planet by reducing carbon emissions. Compostable plastic is biodegradable, but not every biodegradable plastic is compostable. Also, a small at-home compost pile typically can’t break down compostable plastic.

These items must be sent to a commercial composting facility with higher temperatures and different breakdown conditions. Some community-wide residential compost collection programs accept compostable plastic, but be sure to ask before recycling your plastics with your local program.


Grass clippings

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Because grass clippings have a high nitrogen and moisture content, they can cause your small compost pile at home to heat up well above the ideal temperature range. Compost that’s too hot can lead to unwanted odors. Furthermore, lawns treated with fertilizers and pesticides can harm your pile and the vegetation you apply it to.


Used personal products

Share to PinterestCute toddler in the bathroom. Little boy putting his hand in the toilet.

Any personal hygiene item containing human feces, blood or other fluids, such as tampons or diapers, shouldn’t be included in your compost bin. Items contaminated with solids or fluids produced by the human body pose a significant health risk.


Citrus Fruit Peels

Share to PinterestMany dry orange peels on white table

Orange peelings, lemon peels, lime peels, and other citrus fruits can fluctuate the pH of your compost bin, slowing down the decomposition process. Also, if you’re using worms as part of the composting process, citrus can kill these beneficial organisms.


Baked goods and cooked grains

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Photo by Kate Remmer on Unsplash

Cooked grains and freshly baked bread, especially those with glazes or a lot of sugar, can breed harmful bacteria. Cooked rice is especially noted for bad bacteria growth in a compost pile. Confections can also attract pests, including flies and rodents.

You can compost uncooked rice and pasta and plain bread that’s so stale that it’s hard. However, you should keep these in moderation and always bury them as deeply as possible in your compost pile.


Coated packaging

Share to Pinterestcontinental breakfast with small individual portion packaged brand with Wholesome Farms reduced fat milk
Kristi Blokhin /

Similar to coatings on glossy pages, coated packaging can also introduce undesirable components to your composting pile. Food packaging made of plastic, foil or other non-sustainable material shouldn’t be placed in your compost. Examples include waxy-lined coffee cups, juice boxes, milk cartons and foil-lined cookie or cracker bags.


What Can You Put in Your Composting Bin

Share to Pinterestgardener's hands in gardening gloves are sorting through compost heap

  • Cardboard egg cartons
  • Chopped or chipped branches and twigs
  • Coffee grounds
  • Crushed eggshells
  • Disease/pest-free houseplants
  • Dry hay, leaves and straw
  • Grains and hops
  • Healthy herbivore manure
  • Natural cork
  • Non-invasive weeds without mature seeds
  • Non-woody pruning
  • Nutshells (minus walnuts)
  • Paper coffee filters
  • Paper towels and toilet paper rolls
  • Pet bedding from healthy rabbits, hamsters, gerbils and guinea pigs
  • Sawdust from untreated wood
  • Shredded brown paper bags
  • Shredded newspaper
  • Shredded, uncoated and sticker/tape-free paper and cardboard
  • Shrub pruning
  • Spent flowers
  • Sticker-free fruits and vegetables
  • Tea grounds and leaves
  • Untreated wood ash (in moderation)

Further information about composting, how to compost and its benefits:



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