Large tropical plants often grow too tall for their space. Also they tend to lose their lower leaves. However, plants with very large leaves lose moisture so quickly that they do not respond well to stem cuttings. For rubber tree, dieffenbachia, croton, and others, air layering is an alternative method that works well. This method allows the top portion of the plant to develop roots while it is still attached and nourished by the parent plant.
Look at the plant and decide where you would like the roots to form. Then make an upward, slanted cut, being very careful to cut only 1/3 to 1/2 way through the stem. (A tall, spindly stem may need to be staked to support the section above the cut.)
Keep the slit open by propping a small stick within the wound. Dust this area lightly with rooting hormone powder. Next, apply very moist sphagnum peat moss around this wounded area, making a ball about the size of a fist. Wrap the moss in clear plastic to hold it in place. Secure the top and bottom with ties. After 3-4 months, roots should begin to appear through the plastic. When this occurs, remove the plastic, cut the stem just below the roots, and plant the rooted stem tip.