An easy way to increase your supply of plants is to grow new ones from cuttings, that is, from pieces of the plant you have. Almost any part of the plant is a possibility leaf, root, or stem but some parts work better for some plants than for others. Stem or softwood cuttings work well for geraniums, begonias, fuchsias, chrysanthemums, carnations, and many other plants. You can propagate azaleas, camellias, roses, and jasmine from stem pieces called hardwood cuttings. Leaf cuttings are good for begonias and African-violets, and root cuttings for poppies, Anemone japonica, gaillardia, and Oriental poppies.
In no other greenhouse operation is cleanliness more important than with cuttings. Obviously, it is essential to take cuttings only from disease-free plants, and then to use only spotlessly clean tools and materials. Even though you plant in a sterile medium and dip cuttings into a hormone powder containing a fungicide, keep in mind that the knife you use, the bench on which you lay cuttings, even your hands, can carry disease to the open end of a cutting. It is a good idea to dip the cutting knife in a solution of laundry bleach between each cut.
To propagate from cuttings, select what we might call middle-aged growth. Very young tips do not have adequate reserves to produce rooted plants soon enough to resist a possible fungous attack. Old growth may have hardened past the root-producing stage and, again, cuttings from it may not be able to produce a root system in time for survival. What you want is the healthy, vigorous plant material that develops midway in the growth cycle of the plant.