Things You Should Never Compost

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Composting makes good sense. Every household creates several types of waste products that can be composted and turned into a rich and nutritious fertilizer for plants and garden crops. Also, composting reduces the load on local landfills. According to the Environmental Protection Agency, about a third of the waste sent to landfills consists of yard trimmings and kitchen scraps that could easily be turned into compost. While there are many types of household waste that can be put in a compost pile, there are also many items that must never be added to one.

Weeds, Seeds & Sickly Things

Most yard waste can be added to a compost pile. But, to maintain a healthy compost pile, only use lawn trimmings, leaves and twigs that have not been treated with an organic insecticide or herbicide. Plant material treated with chemical pesticides can harm or destroy beneficial composting organisms.

Plants that show signs of disease or a pest infestation should never be put in a compost pile. Many times a compost pile will not become hot enough to destroy these pests and the pests will remain in the compost. When the compost is amended into the soil, the pests will be transferred to the plants where they will begin a new life cycle.

Weeds and plant seeds may also be given a second chance in the compost pile. The rich compost makes the perfect growing condition for sprouting seeds and encouraging the growth of weed roots.

Meat, Dairy, Pasta & More

Kitchen scraps are the mainstay of the compost pile but not every scrap of kitchen waste can be added to a compost pile. Fruit and vegetable scraps, eggs shells, coffee grounds and tea leaves can be added. Other kitchen waste must never be added because the odor created by the waste will attract rodents and flies. Here’s a list of kitchen waste that must never be put in the compost pile:

  • Dairy products such as butter, cheese, milk, sour cream, yogurt and eggs.
  • Fats, grease, lard and oils.
  • Meat, chicken and fish including the bones, blood and other scraps.
  • Food high in carbohydrates (for example, pasta, grains and breads) can also cause mold problems.
  • Mayonnaise, salad dressing and peanut butter does not break down easily in the compost pile.
  • Plate scrapings from people with a cold, the flu or other illnesses.
  • Any foods that have been seasoned with salt.

Magazines & Metallic Paper

Not all paper products are created equal. Newspaper and paper towels printed with soy inks can be composted. These inks are non-toxic and biodegradable. Coated papers and paper contain metallic inks and foils cannot be composted. Instead of composting these items, send them to the recycling bin. Here is a list of paper products that must never be composted:

  • Magazines and catalogs made with glossy, slick paper.
  • Metallic and foil papers such as greeting cards and wrapping paper.
  • Coated cardboard containers such as juice and milk cartons.
  • Colored newsprint paper.
  • Plastic grocery bags, plastic containers, Tyvek shipping envelopes and Styrofoam.

Personal Hygiene & Medical Supplies

Diapers and personal hygiene products contain feces or blood that carry pathogens to the compost pile and create a health risk. Medical waste also poses a health risk; bandages contain blood and medications add toxins to the compost. These items may contain diseases that will make you and your family sick.

Kitty Litter & Doggie Poo

Fido and kitty may be your best friend but they will never be friends with your compost pile. Pet feces and litters contain harmful parasites, bacteria, germs and pathogens that are harmful to humans. Manure and bedding material from poultry and non-carnivorous animals (including cows, horses and rabbits) are beneficial to a compost pile. Manure from meat-eating animals and livestock that are given antibiotics cannot be used in the compost pile. Pet hair is one of the few pet wastes that can be put in a compost pile.

Construction & Other Hazardous Waste

Some types of wood can be composted. Tree limbs and sawdust from untreated lumber are safe for the compost pile. But, much of the wood waste from a construction or building project may not be suitable for a compost pile. Lumber used for buildings is pressure-treated and contains toxic chemicals that can harm the microbes that turn trash into compost. Other hazardous materials that should not be used in a compost pile include:

  • Batteries, household chemicals and their containers, motor oil and antifreeze.
  • Household glass and compact fluorescent light bulbs can be recycled.
  • Cigarette butts.
  • Any petroleum-based products, rubber, metal and chemicals.

Before you throw anything into a compost pile, make sure that the material will break down and not be harmful. When in doubt, a good rule of thumb to remember is that anything that was once a plant can be turned into compost.

Last Updated: June 26, 2012
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About Coletta Teske Coletta Teske has 25 years' experience in tech journalism, as well as home and gardening topics. She has freelanced for Fortune 500 companies such as Boeing and Microsoft, published more than two dozen computer books for Prima Publishing and Macmillan, and worked as a freelance correspondent for West Hawaii Today. Coletta has been an avid gardener since she was 2 years old. While living in Hawaii, she achieved a lifelong dream of becoming a certified master gardener.

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