How do we use plant hormones to produce large numbers of new plants quickly?

Hormones are chemical substances produced in organisms that have a desired effect on a specific tissue or set of tissues somewhere else in the organism.  There are several hormones that foster different aspects of plant growth, such as auxins.  Auxins contribute to the elongation of plant cells.  For this to happen, the otherwise rigid cell wall has to be less rigid and more plastic, allowing the cell to elongate.  Another hormone is a substance called ethylene, which stimulates the ripening of the plants fruit.  This is a critical part of plant development, as it fosters distribution of the plants seeds for reproduction.  Finally, a hormone called cytokinins is responsible for cell division in plants, which is necessary for the plant to grow, mature, and reproduce.  All these hormones produce specific growth and reproductive characteristics required by the plant to flourish and multiply.