Leaf mold is a form of compost produced by the breakdown of shrub and tree leaves.
Due to the slow decaying nature of their lignin (cellulose) content, autumn leaves break down far more slowly than most other compost ingredients, and therefore should be composted separately. This can be achieved either by placing the collected leaves in plastic bags (taking care to avoid collecting from areas that may be subject to high levels of pollution, e.g., roadsides), or in specially-constructed wire bins as illustrated in the diagram below.
Leaves take between one and two years to break down into rich humic matter with a smell reminiscent of ancient woodland. While not high in nutrient content, leaf mold is an excellent bulky and fibrous soil conditioner.
Leaf mold bin constructed with posts and wire