There are two ways by which one can propagate a plant: sexually or asexually. Asexual propagation involves removing a part of a living plant and growing the removed portion into a new and separate entity.
Asexual propagation is very popular for a variety of reasons. Initially, it can be an inexpensive means by which to multiply the given population of a plant. Additionally, there are some varieties of plants which seem to respond exceptionally well.
There are a variety of means by which one can implement asexual propagation. Three of the most common methods are via the use of cuttings, layering and grafting.
Cuttings
Use of cuttings is a common propagation strategy. One severs a portion of a living plant that then regenerates itself into an additional complete plant. Cuttings are commonly used because the method meets with success when either herbaceous or woody plants are used. The strategy is also popular because it tends to reproduce exact models of the original, or "mother plant." As William Davis noted in his wonderfully comprehensive look at the subject, Plant Propagation, "Next to raising plants from seed the system of propagation most extensively practiced is that of striking or rooting cuttings. By this method the characters of the parent are exactly reproduced, which is not always the case with seedlings, as they are often subject to considerable variation." Sometimes this is referred to as "cloning" a plant, as the characteristics of the other are completely duplicated in the new plants.
The portion of the plant removed, the cutting itself, is always made free of buds or flowers of any sort. These features are removed so that all of the cutting's energy will be expended upon growth and develop-instead of being "wasted" on maintaining other features.
The cutting is then placed in a rooting medium. Usually, the propagator seeks a medium that allows high levels of oxygen flow while retaining low levels of fertility. This tends to produce quicker root growth and helps the cutting regenerate into a fully functional plant.
Layering
Layering is another means of asexual plant propagation. In these situations, one allows part of an-already living plant to develop roots of its own. The dually-rooted plant is then severed into two distinct plants. Layering works because the branches and outgrowths of many plants have a tendency to develop "their own" roots when in contact with an appropriate medium.
There are various ways to effectuate layering. Some layering methods include tip layering, compound layering, mound layering and air layering. Though different in exact implementation all share common characteristics, including the need to use an appropriate rooting medium.
Layering is not always a human-influenced process. Many plants naturally propagate themselves using layering. Ferns with runners, plants with suckers, and bulbs that divide into multiple plants when left to their own devices are all engaged in layering.
Grafting
Grafting refers to combining a part from one plant into another living plant. This methodology is often used with trees and other particularly sturdy plants as a means of propagation. Grafting is a valuable tool in situations where a particular plant would fail to thrive under other methods.
There are a variety of requirements to successful grafting. One cannot simply decide to merge any two plants of their choosing. There must be general compatibility, the cutting and main plant must be at appropriate levels of maturity, for instance.
Grafting also requires a great deal of care after the initial procedure. The new insert must be appropriately bound to its host, which can require a great deal of experience and talent to do properly. Regular inspection is needed and maintenance may be required for many years in some cases.
Asexual propagation of plants provides a means produce new plants without sowing from seed. It can be a wonderful means of plant propagation. Although any number of methods have been used to asexually propagate plants, cutting, layering and grafting are three of the most common. These three techniques provide an interesting introduction to the various routes one can take toward plant propagation.
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