When the leaves are removed from cut flowers, they lose their source of food for energy. Sucrose, or sugar, provides carbohydrates for the energy the flowers need to continue blooming and living.
Biocides, such as bleach, combat bacteria, fungi and yeasts. These microorganisms feed on sap from the cut stems. As they grow, they plug the tiny tubes in the stems that carry water and nutrients to the flowers. As a result, the buds do not open, the leaves wilt, and the stems weaken and bend.
Most water supplies are alkaline, which reduces the life of cut flowers by closing the stems. An acidifier such as citric acid helps adjusts the pH and aids in the uptake of water. Acidifiers also stabilize the pigment of the flowers, and prevent muddy or grayish colors.
Flower foods made from ingredients from your kitchen or bathroom can prolong the life of cut flowers. The simplest solution consists of two ounces of a mouthwash that contains sucrose and a bactericide in a gallon of water. Most mouthwashes are naturally acidic. Another easy solution to make is three cups of water, one cup of lemon-lime soda (non-diet) and 1/4 teaspoon of bleach. The most common solution is a quart of water, one teaspoon of sugar, one teaspoon of bleach, and two teaspoons of lemon or lime juice.