Cloning is one of the best ways to propagate shrubby plants like rhododendron. Cloning, also called vegetative or asexual propagation, is how large growers produce thousands of identical plants at one time. Rhododendron is among the easier shrubs to clone and is sometimes done by the home gardener.
Cloning produces new plants which are genetically identical to the parent plant. Plant propagators use tissue from the parent plant, encourage root growth, then establish the new plant in its own pot or new location. Asexual propagation is contrasted with sexual propagation where two plants contribute genetic material to produce a seed from which a new, unique plant will grow.
Cloning rhododendrons produces plants true to the parent plant. Sexual reproduction can lead to offspring which have undesirable characteristics. Cloning assures that all of the beneficial characteristics of the parent plant are represented in the offspring. This is often a consideration with color, size, hardiness and disease resistance. It also cuts down on the time and resources required to establish large quantities of new plants.
The methods used to clone rhododendrons are usually cutting and layering. In cutting, a plant tip is taken from the rhododendron, dipped in rooting hormone and placed in a light, well-drained medium until there are sufficient roots for transplanting to the garden. Layering consists of simply bending rhododendron branches down to the ground, covering part of it with soil and pinning the branch in place until roots grow. The new plant is separated from the parent when it has rooted sufficiently to be dug up and planted on its own.
Cuttings are usually taken from August to October and placed in the garden or a larger pot the next spring. Rhododendrons can be layered in spring and separated from the parent and planted in early fall or the following spring.
If you want to clone your own rhododendrons, you only need a few tools. A sharp knife ensures clean cuts, rooting hormone helps rooting, and a stiff wire keeps layered branches pinned to the ground.