While bread crumbs can be broken down, there are several factors that make it a problematic addition to a compost pile. First, bread is a compound food, which breaks down more slowly than yard waste or vegetables. Secondly, garden pests love bread and they will tear up your compost pile to get to it. Consequently, the best way to compost bread crumbs is in a compost tumbler. These compost bins are easy to turn several times a day to facilitate the decomposition of bread crumbs. Plus, their compartments are sealed, which makes them inaccessible to even the most determined critters.
Make sure that your bread crumbs are in the smallest pieces possible. A great way to do this is to allow the bread to dry, and then crumble it into small pieces.
Spread the bread crumbs over the existing compost in your compost tumbler. Bread should not be the only organic material in your compost bin. Add some other, more easily broken down, matter into the compost bin if necessary. Ideal items include yard waste, vegetables or any other organic matter that is in its natural state.
Add a composting accelerant to the compost tumbler according to the manufacturer's instructions for the amount of organic material in your compost bin.
Turn the compost bin three times daily.