A reader has requested clarification regarding the use of a floral conditioning solution (e.g. Chrysal RVB) vs. a floral preservative solution (e.g. Floralife, Oasis or Chrysal Cut Flower Food). The concern is well-founded because the terms are easily confused and somewhat misleading. First, please note the use of the terms conditioning and hardening in the previous article. These terms describe two time periods in the processing of cut flowers. Confusion sets in because both conditioning and preservative solutions can be used during the conditioning and hardening periods! To thoroughly describe the use of solutions with cut flowers, lets first characterize the entire cut-flower process (from the perspective of a rose exhibitor) as follows.
The Cut-Flower Process (for Rose Exhibitors)
Step 1. The bloom stem is cut from the plant, and the stem is immediately re-cut under tap water, then transferred into a container of lukewarm water or solution.
Step 2. The bloom stem stands in lukewarm water or solution for a period of time (say, 30 to 60 minutes) to maximize uptake of water. This is the conditioning period.
Step 3. The bloom stem is refrigerated, standing in water or solution, for a period of time (say, one to two hours) to slow the transpiration rate to a minimum. This is the hardening period.
Step 4. The bloom stem continues in refrigeration, standing in water or solution, until it is needed for display. This is the cold storage period.
Step 5. The bloom stem is removed from cold storage, and transported and/or used for display. In either case, it will slowly warm up to room temperature during this period.
Now, the question arises: which solution is appropriate for which time period? In general, a floral preservative (cut flower food) can be used for all five periods, but a conditioning solution (Chrysal RVB) can only be used for Steps 1 thorough 4.
A floral preservative contains an agent to kill bacteria, an ingredient to acidify or lower the water pH (which makes it easier for the stem to take up water), and a nutrient to feed the bloom. Note: Listerine mouth wash also contains these three elements and is therefore recommended as a home-made floral preservative.
Because a nutrient (a form of sugar) is included in the floral preservative solution, the solution must be changed during Steps 4 and 5, every three days or so. The container must also be changed or washed with soap and/or bleach at this time, and stems re-cut to expose fresh surfaces. While the anti-bacterial agent fights stem decay, the nutrient promotes it, so the situation is a stand-off or balancing act.
Now, the floral conditioning solution is significantly different. It was designed to re-hydrate bloom stems that have been shipped out-of-water, as commercial rose growers must do. Like the preservative solution, the conditioning solution contains an agent to kill bacteria and an ingredient to acidify or lower water pH, but instead of a nutrient, the conditioning solution contains a chemical which dilates the stem cells to maximize water up-take. Unfortunately, this chemical can do damage if stems are left standing in it for a prolonged period of time (say, more than 12 hours) at room temperature, therefore, the conditioning solution is not suitable for Step 5 in the cut flower process!
The good news: roses can stand in the conditioning solution for two weeks or more in cold storage, without re-cutting stems or changing solution! On the down side, the conditioning solution does not provide any nutrients, so some varieties may experience a slight loss of color in the bloom and a loss of flexibility in the foliage during very extended storage.
Theoretically, the optimum process would be to use a conditioning solution for Steps 1 and 2 (through the conditioning period, of course) and a preservative solution for Steps 3 through 5, changing it as often as required. However, for expediency, I have used only conditioning solution for Steps 1 through 4, and tap water thereafter. Not only does it minimize the labor of holding roses in cold storage, it tends to fix the stages of blooms, rather than encouraging blooms to continue development, as a nutrient would do. Note: a few years ago, dry-wrapping roses to hold them in cold storage for an extended period of time was all the rage among avid rose exhibitors. That was before the discovery of the conditioning solution Chrysal RVB, manufactured by Pokon Industries in The Netherlands. If you still dry-wrap, a conditioning solution would be ideal for re-hydration.
To summarize: A conditioning solution is designed to maximize hydration of a cut flower, especially if the flower has been out of water for some time. It can also be used for hardening and cold storage, and is especially useful for extended cold storage. A preservative solution is designed to extend the life of a cut flower, providing nourishment while retarding bacterial decay. It can be used throughout the cut flower process, but the solution must be changed and the container cleaned every three days or so, to be effective.
This article first appeared in the 2Q96 Rose Arrangers Bulletin, an official quarterly publication of the American Rose Society.