Cutting stems on an angle: It matters not whether you cut flower stems straight across versus on an angle. Do whatever is easiest.

Role of sugar: Sugar retards water uptake, which is one reason hydrating solutions don't contain sugar (see below). If flowers arrive very dry, don't place them immediately into a fresh-flower food solution. Properly hydrate them first. However, once hydrated, flowers must be transferred to a fresh-flower food solution, which, by definition, contains sugar (food).

Hydrating solutions: Commercially available products can be used as hydrating agents. Many are either citric acid or aluminum based. In addition, while not specifically available in a commercial floral product, chlorine from household bleach is used, too.

• Citric acid versus aluminum based: Researchers in the mid 1970s demonstrated the benefits of low pH solutions (about pH 3.5) for increasing water uptake in roses and other flowers. After testing many acidifiers, citric acid proved to be the best. Citric acid is known to have a number of positive effects on flowers such
  • May act as a germistat to control germ growth because of the pH
  • Can not only reduce solution pH but can act as a buffer
  • Can act as a chelator to hold and transport certain nutrients
  • Improves solution uptake
  • May act as a food source
  Recommendations about making up and using citric acid solutions, especially on roses, soon followed. However, industry professionals found out that proper sanitation procedures were absolutely essential to avoiding microorganisms. In addition, self-manufacture of citric acid solution had regulatory implications, mostly from the Environmental Protection Agency. Floral companies may have difficulty obtaining these regulations.

  Many of the earliest fresh-flower foods contained aluminum, mostly in the form of aluminum sulfate. That is still true today and researchers have demonstrated over the years the benefits of this compound. Aluminum-based solutions:

  • Can act as a modest germistat to help control microbe growth
  • Can reduce solution pH
  • Can complex certain chemicals, ions, dirt, etc. out of solution
  • May influence stomata function and hence transpiration
  • Can influence flower color
  • Can influence water uptake
  Aluminum- versus citrate-based products play different roles. Specifically, aluminum-based ones retard flower development by slowing, but also maintaining, solution uptake. Citrate-based solutions enhance solution uptake, so as to prevent bent-neck symptoms. Unfortunately, these differences are not always obvious or consistent. Research and experience findings presented below demonstrate some of the differences.
  • Citric acid-based products perform better, while aluminum containing solutions are less consistent when used in rose-hydration, especially when stems have not been re-cut later in the marketing channel. In short, if aluminum-based hydrators are used at grower/bouquet manufacturer level, the stems must be re-cut once the customer receives the product or reduced vase life is almost assured (aluminum flocculation probably causes a physical blockage to solution uptake at the base of the stems).
  • Aluminum-based products are more susceptible to water quality changes because the aluminum solubility is very pH dependent.
  • Citric acid-based products can be toxic to some flower cultivars at high concentrations.
  • If flowers are placed in citric acid solutions for too long or under the wrong temperature conditions or if the flowers are old or have been improperly handled prior to treatment, rapidly opening flowers may result. While this has a downside, it also offers a good measurement of old or improperly handled flowers at the time of treatment. No chemical treatment can overcome aged flowers.
  • The responses of roses to citrate- and aluminum-based products is often confounded by the cultivar being tested. For example, water uptake characteristics of three common rose cultivars-'Visa', 'Royalty', and 'Madame Delbard'-are quite different. Therefore, responses to these products can be very different, depending on the physiology of the flowers at the time of treatment.
  • If your goal is to make sure flowers look fine when they leave your business-and you don't care about end-user life-aluminum-based products are better because flower opening is delayed. In the same vein, if you are dealing with old roses, you most likely will prefer the aluminum-based products. However, in both cases, flower performance at consumer level can be unsatisfactory. Unfortunately, short-term goals sometimes outweigh the benefits of end-user flower performance.
• Chlorine based hydrating solutions: For decades, growers, wholesalers and retailers have been adding various amounts of bleach to flower buckets to control microorganism growth and improve flower hydration and flower life. Until recently, no product was labeled for this use. Now a leading manufacturer of bleach has stated that their product can be used at one teaspoon per gallon of water to help control microorganisms and extend flower life: a finding confirmed by research for some crops like baby's-breath and roses. After using a bleach solution for an initial hydration step at grower, wholesale and/or retail level, make sure the flowers are transferred to a fresh-flower food solution. Only add bleach to water: do not add bleach to hydrating, STS or fresh-flower food solutions, as the chemicals may not be compatible.

Information reprinted from SAF Flower and Plant Care Manual, (Society of American Florists: Alexandria, VA, 1994), pp. 147-150.