There are several methods of preserving flowers, but a common technique is to replace the natural sap and moisture in the flower with a preserving liquid, such as glycerin. Glycerin is also used in foods such as candy, pastries, and margarine. This preserves the structure of the flower and keeps it flexible and vibrant.
The result is a flower that looks and feels like a fresh flower, but can be stored for long periods of time without water or special care.