Extending Bloom Vase Life
by Carolyn Elgar, Master Rosarian, Orange County Rose Society
This is a 2015 Award of Merit article
One of the nicest things about growing roses is the ability to have them in vases inside where you can enjoy their color and fragrance at your leisure. This is especially so during this time of year when outside chores have diminished and you are enjoying the last flush of the season. However, roses can fade quickly once they are cut off from their life source and brought into a different environment. How can you increase the life of a newly cut rose in the vase?
Several things happen when you cut a rose from a bush. The tube (xylem) inside the stem that conducts water to the bloom is severed and the source of plant sugars is removed. After it’s placed in the vase, a bloom continues to transpire through its leaves and petals; water is drawn up the xylem to keep the bloom hydrated while it opens. It also uses up whatever sugars it has after it’s cut.
Reduction of water uptake happens in the stem when vascular occlusions, caused by air bubbles, microbes, or injured plant cells, restrict the flow, causing dehydration and bloom wilt. The balance of water levels within the stem and the transpiration of the bloom is important for the maintenance of petal firmness (turgidity).
Lots of research has been done on what the industry refers to as “post-harvest” care. Commercial growers, florists, and wholesalers value cut flower freshness because that’s what people buy. On a large scale, product appropriateness and effectiveness becomes
most important, resulting in information that can also benefit the home rose grower as well as commercial interests.
LEFT TOP starting vase, LEFT RIGHT next day vase: The two Kardinal buds were cut from the same bush at the same time. Both were cut under water so that the stems were the same length. An equal amount of foliage was left on each of them. The flower on the left was treated with tap water with preservative and three ice cubes. The one on the right received plain, room temperature tap water. Although the one on the right looked better in the morning, later in the day, the slower blooming one on the left held up longer. Disregard petal damage which was there when the blooms were cut.
Most of the research concurs that cut flowers benefit from access to replacement carbohydrates or sugars in the vase solution. However added sugars promote bacterial growth, and the increase in bacteria is more detrimental to vase life than lack of carbohydrates. This is because bacteria will block the water flow up the xylem, producing dehydration. Adding a biocide of some kind can suppress microbe growth, making it important as part of the vase solution. Finally, the water quality and pH of the solution is important. Tap water contains a number of substances and is usually too alkaline for rose blooms, which prefer a level around 3.5, close to the pH of their sap. Using deionized water and adding a pH adjusting agent will also help suppress microbe growth and fix petal color. These three items, food, bacteria suppressant, and pH adjuster, increase vase life.
In all of the research, plain tap water was the least effective at maintaining bloom life in the vase. Flower preservatives that are available for the home gardener increase vase life and contain the three necessities: sugars, microbe growth retardant, and a pH adjuster.
Varied product usage
Flower preservation is an established business in the cut flower industry. Wholesalers who sell to florists, supermarkets, and other retailers use storage or holding solutions to keep roses hydrated for extended periods of time. They also may treat cut blooms with silver thiosulfate (STS) to control the effects of ethylene gas. STS is not available to the home market because its usage has to be strictly controlled. However, research is not conclusive on how much rose bloom life is affected by ethylene gas, but increased exposure to this product in supermarkets where fruits and vegetables are ripening may make this more of a concern for commercial wholesalers.
The other people you will find using multiple products to increase vase life are rose exhibitors. Bloom substance is of key importance; exhibitors’ blooms have to hold up for a long time, especially if cut early because of weather or time concerns. Using these products slows down the developing process of the bloom, giving the exhibitor more control over its appearance. In addition, most serious exhibitors have a carefully calibrated refrigerator in the garage to keep the blooms at a constant, cool temperature.
Research also concludes that different plant species and varieties have variations in their genetic makeup that hastens or slows bloom deterioration; studies show that vase life and flower opening are variable, affected by genes that relate to stomatal responsiveness, regulation of water loss, and biochemical processes. Additionally, fragrance has no affect on bloom life in roses.
Some physical factors involved in cutting roses are important also. Long stems are good because they provide a larger source of carbohydrates to the bloom. After the stem is cut, there is an immediate uptake of air, leading to a bubble that blocks the xylem tube. It is essential to re-cut the stem under water. When cut blooms are brought inside, before they are placed in the vase, the stems should be plunged under water where an inch or more should be cut off to open the xylem above the air bubble. This will increase water flow in the stem. Don’t keep cut roses in a hot place, under lights, or anywhere that will increase its temperature and its transpiration. Replace water when needed.
Cold water in the vase
Finally, one of the most interesting things found in the research on this subject is the relationship between water temperature and bloom vase life. Studies conducted in the last ten years demonstrate that cold water facilitates water flow in stems. One interesting study showed that the longest bloom life occurred in deionized water, with a preservative, at a temperature of around 45 degrees Fahrenheit. This temperature was maintained by using a vase that contained a cooler.
Other studies also conclude that cold water affects bloom opening and vase life. Low temperature water has been found to maintain water conductance in the stem, increase water absorption, and dissolve gases that cause air bubbles. Cold water suppresses bacterial growth in the vase, especially in the early stages of bloom opening. Some researchers found that low temperatures keep hydrogen bonding stable in water, maintaining the tension levels in the xylem tissue which stabilizes water conductance.
What is the take away of all this knowledge? Cut as much stem as you can for each flower. Re-cut your blooms under water, far enough up the stem to dispose of the air bubble. Use a flower preservative and follow the instructions; the ingredients in the preservatives are designed to work together if used exactly as directed. Most preservatives dissolve in room temperature water.
If you want to do more, use cold water, perhaps with a few ice cubes, in the vase. Experiment with this idea to see if it increases your blooms’ vase life and slows deterioration.
Research available upon request.
Flower Food box info:
Flower foods for the home gardener contain three main ingredients: food sugars, pH adjuster, and stem absorption enhancers which have anti-bacterial properties. Companies make many different kinds of preservatives for flowers, geared towards professional, commercial, and retail sales. Stay with the products for the home gardener to best suit your needs. The
following are resources for flower foods. You can find information about how their products work and which may be the best choice for your purposes.
Chrysal www.chrysalusa.com (800) 247-9725
Floralife www.floralife.com (800) 323-3689
Oasis oasisfloralproducts.com (800) 321-8286
SaferGro www.safergro.com (805) 650-8918