A single flat of rhododendron cuttings contains approximately a hundred and ten cuttings of one cultivar. Many flats of each of the many cultivars are necessary to sustain a production nursery that grows rhododendrons. Growing rhododendrons from cuttings is the most efficient and practical method of propagation when quantity must maximized. However, those of us who want only a single copy of a favorite cultivar or species have no need for even a single flat of a hundred and ten cuttings.
Propagation by rooting cuttings is still the most efficient form of propagation for many species that are very easy to root, such as jade plant or geranium, that can simply be ‘stuck’ directly where any new specimens are desired. Those who have a greenhouse in which heat and humidity can be optimized may prefer to root cuttings of a few other less cooperative species or trees that lack limbs near to the soil that can be ‘layered’. Nevertheless, if only a few copies of a specimen are desired, ‘layering’ is still perhaps the most reliable form of propagation and certainly does not require the attention demanded by rooting cuttings.
The simplest layering involves rooting a stem directly in soil while it is still attached to the parent specimen. For example, when I wanted a single additional specimen of English holly, I 
found a stem on one of the established specimens that could be bent downward so that a few inches of the length of the stem could be buried adjacent to the parent specimen with the few inches of foliated stem extending above the soil beyond the buried section. Before burying the stem, I cut partially through it to inhibit vascular sustenance from the parent specimen and to encourage vascular independence. The cut was approximately two thirds of the way through the stem and located on the section of stem that was buried.
The cut should be on the underside of the stem so that it is held open as the stem is bend downward to be buried in the soil. Some prefer to wedge a small pebble into the cut to insure that it remains open. Rooting hormone rubbed into the wound promotes rooting of most species. I prefer to bury a few inches of stem beyond the wound, but most roots actually emerge from the wound rather than from bare stem. Prior to rainy weather, irrigation is important.
Stems layered now should be sufficiently rooted to be pruned from the parent in summer. Most species develop undifferentiated ‘callus’ growth around a buried wound through winter with a few roots, but produce more roots as vascular activity resumes in spring. The ‘umbilical cord’ stem may be pruned completely away from the parent specimen, and away from the copy where roots have emerged. The rooted copy can then be installed elsewhere in the garden.
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