Not all organic wastes will break down completely or safely in a backyard composting system. Home composters (and especially beginner composters) should avoid certain items that may be more problematic.

Garden Wastes: Diseased plants, chemically-treated plants or grass clippings, weeds with weed seeds, etc.

Kitchen Wastes: Butter, fats, cooking oils, meats (cooked or raw), bones, fish scraps, milk or dairy products, salad dressing, cooked foods with excessive oils/sauces, seeds, dishwater, etc.

Animal Manures: Cat, dog, bird manures or cat litter bedding

Other: Ashes/coal, treated/painted wood, colored mulch products, waxed cardboard, glossy paper, paper towels with cleaning chemicals, compostable packaging