Floral Preservatives and Cut Flowers
Whether cut flowers are grown in a home garden or in a greenhouse by commercial experts, their care is a science.
To keep cut flowers beautiful longer; remember that they have been removed from their source of water, the root system, and will wilt quickly if not placed in water. Cut stems should be placed in water immediately, as air will rapidly move into the water-conducting tissues and plug the cells. This is why the cut flower that has been out of water more than a few minutes should have a small portion of the lower stem cut off so that water will move up freely when it is returned to water. Cuts can be made under-water to assure no air enters the stem.
A cut flower also has been removed from a major source of food—the leaves on the plant to which it was attached. Although the leaves on the flowering stem make food, once indoors they are in a reduced light situation and this limits available carbohydrates.
Use a Preservative
Commercial preservatives will increase the life of cut flowers and should always be used. (Adding aspirin, wine, or pennies to cut flowers
WILL NOT help to keep them fresh longer. Do not attempt a home brew concoction.) A floral preservative is a complex mixture of sucrose (sugar); acidifier, an inhibitor of microorganisms; and a respiratory inhibitor. Sucrose serves as a source of energy to make up for the loss of the functioning leaves and insures continued development and longevity of the flower.
An acidifier makes the pH of the water more near the acid pH of the cell sap. Most water supplies are alkaline and can reduce the life of cut flowers. The acidifier also stabilizes the pigment and the color of the flower. This is why red roses turn "blue" when placed in water without a preservative or acidifier.
A microorganism growth inhibitor is perhaps the most important part of a floral preservative. Bacteria and fungi are everywhere and are ready to enter the cut surface of the stem and multiply. Prior to actual decay symptoms, cells of the water-transporting tissues can become blocked with microorganisms, inhibiting water uptake.
To aid the floral preservative in slowing down microorganisms, always clean the vase or container. Also remove all leaves below the water surface, as they soon deteriorate. Water and water uptake are major factors in keeping cut flowers fresh.
A process called "hardening" ensures maximum water uptake. It simply means placing the freshly cut stem in 110° F (43.5° C) water (plus preservative). Place in a cool location for an hour or two. Maximum water uptake is attained because water molecules move rapidly at 110° F (kinetic energy) and quickly move up the stems. Flowers at cool temperatures lose less water. In this one brief period while the water is cooling, freshly harvested stems, leaves, and flowers take up almost as much water as in the balance of their life.
Other Tips for Long-Lasting Cut Flowers
Check the water level of the container or vase daily and add water plus preservative when needed.
Keep flowers away from hot or cold air drafts and hot spots (radiators, direct heat, or television sets).
While both drafts and hot spots increase water loss, hot spots reduce a flower's life by speeding transpiration (water loss) and respiration (use of stored food such as sugars) and increasing development (rate of petal unfolding).
When away from home, move the flowers into the refrigerator or the coldest (above 35° F/1.5° C) spot in the house. Again, this will slow down water loss, respiration, and development.
Never store fruit and flowers together. Apples produce ethylene gas, a hormone that causes senescence, or aging, in flowers.
In summary, to keep cut flowers longer:
ü Recut the stems and remove excess foliage.
ü Harden the flowers by setting them in warm water in a cool place.
ü Use a floral preservative.
ü Keep them cool and avoid drafts, hot spots, and television sets.
ü Use a clean vase or container and check the water level daily.
Mary H. Meyer, Extension Horticulturist
Department of Horticultural Science
Original Article source:
http://www.extension.umn.edu/distribution/horticulture/dg7355.html
