What Not to Compost
Do NOT compost the following:
* Black walnut tree leaves or twigs
o Releases substances that might be harmful to plants
* Coal or charcoal ash
o Might contain substances harmful to plants
* Dairy products (e.g., butter, egg yolks, milk, sour cream, yogurt)
o Create odor problems and attract pests such as rodents and flies
* Diseased or insect-ridden plants
o Diseases or insects might survive and be transferred back to other plants
* Fats, grease, lard, or oils
o Create odor problems and attract pests such as rodents and flies
* Meat or fish bones and scraps
o Create odor problems and attract pests such as rodents and flies
* Pet wastes (e.g., dog or cat feces, soiled cat litter)
o Might contain parasites, bacteria, germs, pathogens, and viruses harmful to humans
* Yard trimmings treated with chemical pesticides
o Might kill beneficial composting organisms
Source: U.S. Environmental Agency