If you are composting by the slow method, keep diseased plants and seed heads of weeds out of your compost pile. For any compost, avoid coarse, woody materials because they break down slowly and make the pile hard to turn.
Some plants contain compounds that slow microbial decay.
Western red cedar, often used for fence posts because of its resistance to decay, can break down slowly in compost piles. Do not add meat or fatty food to the compost pile. Do not add dog, cat or pig feces . A compost pile will only ignite if it has a very hot zone next to a dry zone. Fires will not start in moist piles or in small, backyard piles.