110° F pile of just leaves.

The power of volume. It is 11°F right now but this pile of leaves, approximately 1 cubic yard, is 110°. It is just leaves – no grass or nitrogen source.

Why is it so hot? Because even fallen leaves have some nitrogen, so there is some bacterial activity going on, and the pile, almost 4’ wide and made entirely of shredded leaves, acts as a great insulator.

The same is true of a similarly sized bin full of an appropriate compost mix. The volume insulates the center of the pile.

The limited nitrogen means this pile, made about a week ago, will cool down within a few days as the lack of nitrogen prevents continued bacterial growth.