In addition to keeping the water clean you can add a flower food and bactericide or floral preservative to the water. If you change the water every day then the preservative will not add much to the longevity of the flowers. Nevertheless, if you want to take the extra step to maximize your flowers' vase life then you can add a commercially prepared floral preservative or make your own. If you wish to make your own, Dr. Joseph E. Houland recommends the following: to one quart of water add 2 tablespoons of fresh lemon juice, 1 tablespoon of sugar and 1/2 teaspoon of chlorine bleach. (Dr. Joseph E. Houland, University of Nevada, So. Florist and Nursery, 11/25/83)
Often called "cut flower preservatives", this product class is now referred to as "fresh-flower foods." This change in terminology responds to consumer perceptions about these products. First, the word "cut" implies death, something cut-off the mother plant. The substitute word "fresh" relates to today's image of healthy and wholesome. Second, the word "preservative" often is identified with harsh chemicals and also suggests something artificial, whereas the word "food" does not.
Fresh-flower food solutions generally contain a food source-sugar-and substances to control microorganisms, such additional ingredients as acids to alter pH; anti-ethylene substances; and agents to precipitate out certain salts and other materials.
Certain non diet, citric acid-based soft drinks have ingredients similar to fresh-flower food solutions, such as acid, water, sugar and preservative called sodium or potassium benzoate. Soft drinks are too expensive to use on fresh flowers, but the comparison demonstrates that the chemistry of fresh-flower food solutions is friendly, not dangerous or exotic.
Fresh-flower food solutions:
Level of industry use: Research and sales reports indicate that approximately 25 to 30 percent of fresh cut flowers are being properly treated with fresh-flower food solutions. Of the remaining, about 20 percent never are put into such products. The remaining 55 to 60 percent are placed into overly dilute fresh-flower food solutions. Note: dilute solutions have some sugar which acts as a food source for microorganisms, though usually not enough to control the growth of these same microbes. The result can be shorter flower life, compared to placing flowers in plain tap water.
Effects on vase life: When used properly, fresh-flower food solution usually increases flower life by 25 to 75 percent or more. Granted, some flowers seem to benefit little, but almost no flower is harmed. It would be impractical to mention a few flower species that do not respond favorably to fresh-flower food solution.
Effects of water quality: Water quality affects all fresh-flower food solutions. No single test will determine which fresh-flower food solution brand is best for any given water quality. Instead, try a series of flower life tests, using two or three fresh-flower food solution brands with two water qualities: tap and deionized water. Purchase the latter by the gallon from food stores. Spring or natural water is not deionized and is often worse than tap water.
Whenever possible, use flowers from the same bunch for each test. Use at least four flowers per treatment. Treatments can consist of: plain tap water, plain deionized water, tap water plus brand A, deionized water plus brand A, tap water plus brand B and deionized water plus brand B. Additional brands can be added the same way.
Run this test for many weeks, using numerous flower types, before deciding. If the deionized water continually out performs the tap water, get product information from a local water conditioning company that sells or leases deionization or reverse osmosis (RO) purification equipment.
Powders versus liquids: Flowers don't know whether fresh-flower food solutions are liquid or powder. Therefore, let the fresh-flower test results, ease of operation, and cost considerations be the deciding factors.
Dispensing systems: To ensure the proper concentration, use automatic dispensing systems such as those used for fertilizer injector/proportioning. "Passive systems" indicate that the fresh-flower food solution is dispensed without the user having to activate the system by, for example, pushing a button. "Active systems" enable the user to use one source for both fresh flower food and water by pushing a button or switch.
Making your own: Don't
Consumer packets: Every fresh-flower stem, bouquet, bunch, and arrangement should include a packet or two of fresh-flower food solution packets for the buyer. If the five- gram or similar size is used, add two packets per sale to make sure a full quart of properly mixed fresh-flower food solution will be available. Some florists should consider having the fresh-flower food solution packet labeled with store logo and care instructions. Most companies which sell fresh-flower food solution packets can make private labeled ones as well, assuming sufficient quantities are ordered.
Information reprinted from SAF Flower and Plant Care Manual, (Society of American Florists: Alexandria, VA, 1994), pp. 156-157.