How do you do marcoting?

Marcotting is an old term for the propagation technique now called air layering, where a stem is induced to form roots while still on the parent plant. The stem is cut partly through and a rooting hormone (auxin) often applied. Then it is wrapped with moist sphagnum peat moss and ties in place with plastic sheeting. When roots are well formed, the branch is cut below the roots to make a new plant. Air layering is used for hard to propagate plants and to rejuvenate houseplants, such as diffenbachia, that have gotten too tall.