If all the materials are on hand, mix them thoroughly throughout the pile. If materials accumulate over time, add new materials to the center of the pile. This practice will help aerate the center of the pile, where anaerobic conditions are likely to occur. The pile must be big enough to hold heat. A hot pile decays much faster than a cold pile.
Small piles are usually colder, because they have small cores that hold less heat.
Small piles also dry out faster. All materials in the pile must be moist but not soaking wet. The mixed material should feel moist, but you should not be able to squeeze water out of it with your hands. At dry times of the year, you may need to add water. In rainy winter locations, a pile may not heat up unless you cover it to keep out rainwater.