layering, horticultural practice of propagating a plant by rooting a branch before severing it from the mother plant. Typically the branch is bent and a section that has been slit or broken on the underside is covered with soil and held in place by means of stakes or pins. Trench layering induces new shoots from a length of buried branch. In mound, or stool, layering, the many shoots of a closely cropped young plant are heaped with soil. Air (or pot, or Chinese) layering is used when the branch cannot be bent to the ground; peat moss or some other suitable rooting medium is attached to a cut place on the branch. Layering is used mostly for multiplying plants not easily propagated from cuttings. Some plants propagate naturally by layering, e.g., raspberries, strawberries, and chrysanthemums.
See bulletins of the U.S. Dept. of Agriculture; H. T. Hartmann, Plant Propagation (1968).