The most common bedding materials for composting worms, include shredded newspaper or computer paper, leaf mold, peat moss, animal manures, coconut fiber (coir), and wood chips.
Each of these bedding materials has its own list of advantages and disadvantages. For instance, leaf mold is a natural habitat for worms, but it may also contain organisms that you don’t want in your worm composting bins.
It doesn’t matter which bedding material(s) you choose, you must always remember to add a couple handfuls of soil, or rock dust, to your worm bin. This is especially important if you are just setting up a new bin. These ingredients add “grit” to the bedding materials in your bin. This grit is very important because your worms use it in their gizzards to help in breaking down food particles. The soil has the added benefit of inoculating your bin with various soil microbes, all of which are important in establishing a healthy ecosystem for your composting worms.