Introduction to Plant Propagation
To produce new plants which are exactly like the parent plants in your home, garden, nursery or greenhouse, use a technique that involves rooting existing pieces of the plant. To produce a plant which is genetically identical to the mother plant "clonal asexual" (also called "vegetative") propagation is needed. Propagation by the rooting of stem cuttings, root cuttings and division, layering, and grafting, and similar techniques all produce new plants that are identical to the original.
The selection of the method is dependant upon the plant variety. Propagation from seed works mainly for annual plants, but often produces variable results. You never know what you will get from seeds! See Cuttings and Grafts, Division and Layering and Grafting and Budding for information on the propagation methods.
Plants propagated from cuttings have the same characteristics as the parent plant. The rapid generation of new roots is necessary for the plant to transport water and essential nutrients from the media. Rooting hormone treatment helps the plant to rapidly develop new roots when propagating from cuttings, and humidity must be kept high while the plants root. Different types of cuttings require different hormone concentrations, so make sure you use the right type - some are for woody stems, and others are for young green shoots.
The most attractive plant is a symmetric plant. After early and symmetric root formation the plant stands solid in the soil, it absorbs water and nutrients, develops uniform shoot, stem and leaf growth and superior total growth. This is why you get a bigger, better plant from a cutting than you do from starting with seeds. See Care of Cuttings for more information.
Propagation of plants by various methods is not a mystery. Some plants propagate better by different "vegetative" means, and some just don't propagate well at all. See Plants to Propagate for lists of houseplants, ornamental garden plants, shrubs and trees that work well, and those to avoid.