Layering is a technique for plant propagation that is in essence a form of taking cuttings; the difference being that in layering, the shoots of the plant are encouraged to grow roots before being severed from the parent plant. This method is particularly good for shrubs that grow branches close to the ground, such as viburnums and rhododendrons, and also for plants such as magnolia, which do not propagate easily by other means.
Layering techniques may be divided into three main groups: air layering, where the growing medium is brought up to the plant stem; techniques where the stem is brought down to the growing medium (natural, serpentine, simple and tip layering); and techniques where the growing medium is mounded over a stem (French layering, mound layering (stooling) and trench layering). The growing medium may be soil, peat, sand, sawdust or sphagnum moss.
This propagation technique is useful for increasing stocks of plants, and whilst it may not be particularly rapid, it produces strong, well-adapted plants without the often labour-intensive steps required when growing cuttings.