Coffee grounds are as high in nitrogen as grass clippings, and can even be brought home by the bucket from gourmet coffee shops. Any food item, including spoiled fruits taken directly from the garden, should always be buried at least one foot into an existing pile. In urban areas or communities with rodent problems, a completely enclosed unit, such as a lidded metal trash can with small holes, is recommended, as are indoor worm boxes. Cardboard and newspaper should be ripped-up into strips and moistened, preferably by soaking in a bucket of water. Materials to Avoid.
Good hygiene is as important for the compost pile as it is for the garden.
It is always best to avoid adding any diseased plant materials since viruses and other pathogens, including nematodes and related pests, are not always destroyed in the composting process. Observe the adage, when in doubt, throw it out. Do not add irritating plant materials such as poison sumac and poison ivy, although nettles will break down completely. Avoid adding any food materials which have been mixed with shortenings, spreads, meats, or dairy products. Add grain-derived foods with caution.