Accumulated dirt, debris and microbes in xylem can be greatly reduced by cutting off about one to three inches of stem tissue, either in air or underwater. Alternatively, there are four ways to rid the xylem of air bubbles to allow for the free flow of solution: cut stems underwater, place stems in warm water, use a citric acid solution or place flowers in deep holding solutions. Each of these procedures will now be explained.

• Cutting stems in air: To reduce the levels of dirt, debris and microorganisms in xylem, remove one to three inches of stem tissue. Use any reasonably sharp instrument (i.e. scissors, knife, paper cutter, pruning shears, etc.).
• Cutting stems underwater: When one to three inches of stem tissue is removed by cutting the stems underwater, most air bubbles are removed, too, as are the dirt, debris and microbe blockers. That's because the filters/valves located at the straw ends prevent air bubbles from traveling further up the stems. At the same time, no air is allowed to reach the newly cut stem surfaces, because the stems are underwater. Once re-cut, the flowers can be immediately removed from the water and placed in fresh-flower food or other solution(s). Florists need to cut flowers underwater only once. Retail florists should perform this procedure when processing. Once the flowers have been allowed to hydrate or harden off for about one hour at room temperature, the xylem should be full of water or solution. These same flowers should be full of water and, thus, have no room or appetite for air. Therefore, they will not need to be cut again underwater, either at time of sale or arrangement.
• Placing stems in warm water: Normal tap water contains a certain amount of dissolved air. If it weren't for this phenomenon, fish could not survive, as they use this air to breath. When water is heated to bath temperature-about 100 to 110 degrees Fahrenheit-some of the air normally present is driven out. When this warm water is allowed to cool, it begins to reabsorb air. When flowers are cut in air and then placed into warm water-then cooled-potentially trapped air at the cut stem ends will be re-dissolved back into the water phase, thus ridding the flowers of blockage caused by air bubbles.

• Using this information, a simple home remedy hydration solution can be easily made. Place hot water (150 - 160 degrees Fahrenheit) in a soft plastic container filled to the top. Tighten the cap and place the container in a refrigerator. As the water cools the container shrinks, air is excluded, and the remaining water is essentially air free - a remarkable scavenger of trapped air and an excellent hydration solution. Flowers cut in air and placed into this degassed water should hydrate quickly.
• Citric acid solution: You can overcome air embolisms by placing flowers cut in air into a citric acid/water solution (about pH 3.5). See hydrating solutions below for further details.
• Solution depth: The deeper the holding solution for flowers, the greater the head pressure created at the cut-stem ends. This greater head pressure pushes water into the stems. Thus, flowers first cut in air and then placed into deep holding solutions have a better chance to revive than those placed into shallow solutions. This procedure should be used only for severely wilted flowers.
  Cutting stems in air versus underwater: If stems are not recut, either in air or underwater, from 40 to 60 percent of the potential life can be lost. If embolisms are not a problem, end-user life will be equal for flowers cut in air versus underwater.

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