Your compost pile isn’t a trash can. Some materials definitely don’t qualify as compost ingredients because they contain pathogens, attract pests, or cause other problems. You must take care to add only the right organic ingredients to feed the decomposition process. Leave out the following items:
Ashes from charcoal barbecues: Dispose of this residue in the trash, not your compost pile or bin. It contains sulfur oxides and other chemicals you don’t want to incorporate into your compost.
Ashes from fireplaces or wood stoves: Small amounts of ash (a few handfuls per pile) are okay if you have acidic soil. Never use wood ashes if your soil is alkaline, however, because the ash increases alkalinity.
Disease- or insect-infested plant material: Pathogens and pests can survive the composting process if the heap doesn’t get hot enough. Just leave this material out — better safe than sorry!
Meat, bones, grease, fats, oils, or dairy products: This kitchen waste may turn rancid and attract rodents and other pests.
Waste: Feces from cats (including soiled litter), dogs, birds, pigs, and humans may contain harmful pathogens that aren’t killed during decomposition.
Weeds with seed heads: Toss the leafy foliage into your compost as a source of green nitrogen, but send weed seeds to the trash. If seeds survive the decomposition process, they’ll sprout wherever you spread finished compost.