Dig at the base of a cinnamon tree. Expose a root that's about the thickness of a wire coat hanger or larger.
Use a sharp knife to cut 1 inch of root for the number of cinnamon plants you want to raise. For example, if you want to grow six new plants, cut at least 8 inches of root, allowing for two extra cuttings in case not all of the root cuttings propagate successfully.
Loosen the soil around the root with the trowel and your hands. Gently pull the cut section of root loose from the soil.
Cut the cinnamon root into 1-inch lengths on a potting table or old cutting board.
Fill a pot to within 1-inch of the rim with potting mix. Gently pat the soil down but don't compact it -- root cuttings need oxygen.
Use a pen or pencil to poke holes in the soil at least 2 inches apart. Make the holes a little more than 1-inch deep. It's fine to root multiple cuttings in one pot. Insert the cuttings in the holes and smooth the soil over the top of them.
Water the cuttings to make the soil moist but not soggy. Push four stakes or craft sticks into the soil near the edges of the pot at equal distances, as though marking the four directions of a compass. They'll support a cover for the cuttings.
Put a polyethylene bag over the pot. This material helps to maintain the right moisture level for the cutting to take root. Use an extra-large rubber band or tie a cord to secure the bag below the pot's rim. Put the pot where it will receive diffuse light; keep it out of direct light.
Keep the pot of cuttings moist. In two months, gradually expose the young cinnamon plants to more light by removing the bag for part of each day.