New Keys Unlock Past Secrets!
Some secrets are just too hard to keep! Joining those ranks, and proving to be a new key for old locks, is a scientific research study revealing for the first time the secrets to the proper-care and handling of flowers. From fundamentals to an itemized checklist, the study presents concise, practical guidelines for every person, stage and aspect involved in the handling chain of cut flowers, foliage, and both potted and bedding plants.
Dr. Terril Nell of the University of Florida-Gainesville and Dr. Michael Reid of the University of California-Davis conducted their research study under the sponsorship of the American Floral Endowment. Drs. Nell and Reid, plant physiologists, drew conclusive links between the conditions of improving quality/freshness/vase life and the three C’s - Cooling, Cleanliness, and Care
Confirmed by extensive postharvest studies, the researchers stressed these vital points:
- Temperature must be properly managed (Cooling) throughout every stage in the delivery process from grower to consumer,
- Wholesalers and retailers must improve sanitation methods (Cleanliness) involving water and buckets, and
- The product cannot be mishandled (Care) at any point in the delivery process.
Dr. Nell states: “Our findings give growers, wholesalers, distributors, and retailers of fresh cut flowers and foliage new standards by which to deal with the nation’s rapidly changing floriculture industry. As the distance between field and market expands beyond domestic shores traditional care-and-handling practices no longer prove adequate.”
The Nell-Reid study confronts this challenge by discovering new keys to old secrets about freshness and postharvest life. Of all their findings, cooling was the most significant key in maintaining quality of harvested flowers. The lack of regulated temperature was identified as the single greatest weakness in the industry’s distribution chain from the grower to consumer, with each degree of rising temperature dramatically reducing the flower’s life.
Fresh cut product must be cooled as soon as possible after harvest, the researchers urge; and regardless of shipping distance, a short truck hop or a jet journey from offshore, non-tropical flowers should be shipped in containers cooled at 33¡ F to 35¡ F. Nell and Reid confirm, “Our studies show that most cut flowers, domestic and imported, are transported at temperatures that usually range from 40¡ F to 60¡ F.”
In addition to temperature, the researchers isolated and studied the following major factors affecting postharvest quality:
Pre-Harvest Practices
How the product is grown and handled in the field and greenhouse are keys to quality and extended life. “Disease-free plants that are properly irrigated and fertilized will likely produce flowers with better appearance and vase performance,” Nell and Reid say. “Additionally, proper acclimation of potted and bedding plants will boost product survival during the rigors of transport and marketing.”
Variety
Research in this area remained in the dark for many years, due to the lack of published information regarding postharvest life of different ornamental cultivars. Nevertheless, Nell and Reid pinpoint certain facts. “Cultivars are developed and introduced for specific attributes such as color, form, disease resistance, and size,” the researchers reported. “Sometimes breeders fail to consider other commercially important attributes. For example, some of the modern aistroemeria cultivars have wonderful flowers but their display life is shortened due to rapid leaf yellowing under commercial conditions.”
In the face of limited knowledge about the many new varieties coming to market, Nell and Reid offer the following advise for growers, wholesalers, and retailers:
- Conduct tests to determine which cultivars perform best.
- Sell flowers and plants by cultivar name, seeking customers’ feedback on specific cultivars.
Maturity
The minimum harvest maturity for a cut-flower crop is the stage at which harvested buds will open fully and have satisfactory display life after distribution. For many flowers this is during the bud stage, while for others it’s when the buds are starting to open, or nearly half open. The study notes that flowers cut in the bud stage and opened after storage, transport, and distribution show distinct advantages over cuttings in more advanced stages. These advantages include “reduced growing time for single-harvest crops, increased product packing density, simplified temperature management, reduced susceptibility to mechanical damage, and reduced water loss.”
Food Supply
Flowers need high levels of carbohydrates (starch and sugar) for proper health. The Nell-Reid research illustrates that “the quality and vase life of many cut flowers can be improved by ‘pulsing’ them after harvest with a solution containing sugar. Pulsing is done by placing cut flowers in a solution for a short period, usually less than 24 hours, and often at low temperatures.”
Light
Storage in darkness and at warm temperatures can cause leaf yellowing in certain varieties; and the leaves of Protea nerifolia turn black when shut off from light. “Such effects can be prevented,” the researchers say, “by maintaining the flowers in high light or by treating the harvested flower with a sugar pulse.”
Water Supply
Cut flowers and potted plants lose water and wilt rapidly. Water loss can be dramatically reduced by storing the product at low temperatures, another reason for prompt and efficient cooling of cut flowers as promoted by the study. Water levels can also be restored by rehydration. To avoid air embolism, bacteria, debris or dirt-all factors that can clog a flower or plant’s plumbing system-the study suggests the following:
- Recut the stems, even if the flowers are not wilted. The dried ends of the stems and accumulated dirt, debris, and microbes in the vessels can be eliminated by cutting off approximately one to three inches of stem tissues with a clean, sharp knife.
- Cut the stems with a clean, sharp knife and place flowers into a properly mixed flower food immediately. Cutting stems underwater may help to prevent air bubbles in the stem, which can block the flower’s food vessels. This is best accomplished by cutting in running water or water containing an effective biocide (such as Clorox) to kill bacteria, which can quickly multiply in standing water. Cutting stems in dirty water without a biocide reduces flower life.
Water Quality
Chemicals commonly found in tap water are toxic to certain ornamentals, the study warns. Fluoridated drinking water is also harmful to gerbera, gladiolus, roses, and freesia. The research further cites that high concentrations of sodium in soft water are dangerous to the health of carnations and roses. As for potted plants, sodium-laced water will result in leaf tip burn.
Ethylene
This gas is produced in large quantities by the natural ripening of certain fruits, aging flowers, and combustion of organic materials such as gasoline and firewood. It has long been known that ethylene is harmful to many flowers and can be found in the air at flower markets and storage warehouses. The study stresses the importance of refrigerated storage as a major precaution against ethylene. Additionally, researchers are working diligently to discover an anti-ethylene solution that will greatly minimize or significantly reduce the destructive effects of ethylene.
Growth Tropisms
The study notes that a flower’s reaction to environmental forces (tropisms) can reduce quality. Some flowers bend away from gravity (geotropism) while others bend toward light (phototropism). Spike-flower crops such as gladiolus will bend upward if stored horizontally, and the Nell-Reid research recommends that such varieties be handled upright whenever possible. It was strongly emphasized that low temperature flower storage will reduce these undesirable tropisms.
Mechanical Damage
Bruising and breaking of flowers must be avoided, the study cautions, “Many disease organisms can only enter a plant through an injury point,” Nell and Reid explain. “Additionally, respiration and ethylene evolution are generally higher in injured plants, further reducing storage and vase life.”
Disease
Flowers are susceptible to diseases. Therefore, demanding proper greenhouse hygiene, temperature control, and minimizing condensation on harvested flowers (steps advanced by the study) reduce product loss caused by gray mold, the most commonly encountered disease organism. The study cities Ronalin, Rovral (Iprodione) and Phyton-27 as fungicides that may be effective against gray mold.
Cleanliness/Sanitation
Another major key to longer life for cut flowers and foliage is sanitation. The Nell-Reid study points out that harmful bacteria, yeast, and other microbes are commonly found on flowers. The study emphasizes these steps to control harmful microbes:
- Thoroughly clean all buckets and tubs before placing fresh cut flowers or foliage in them. Remove dirt with commercial bucket cleaner or anti-bacterial solution and a brush and/or rinsing container with 1 part household bleach to 10 parts water; rinse and allow container to drain. Using white buckets makes it easier to see the dirt.
- Add anti-microbial compounds, or biocides found in effective commercial fresh flower foods (preservative), to all water in which flowers are placed. “It is vital”, the study notes, “that the fresh flower food be used at the recommended concentration. Improperly mixed preservatives will not provide the proper balance between biocides and sugar, thus reducing flower life. “
The Nell-Reid study concludes on a key point: Cooling is the primary factor in the postharvest handling of fresh cut flowers and foliage, urging that flowers be pre-cooled directly after packing.
Once packed, flowers are hard to cool. The researchers suggest the best procedure is to pack flowers in an adequately cooled room. “The packing of flowers leaves much to be desired,” Nell and Reid, say. “Flowers taken from a cool room into a warm space for packing will develop condensation, which may increase disease.” The researchers emphasize the importance of keeping the flowers cool and dry.
Nell and Reid spent 4 years analyzing and advancing their new keys for unlocking the secrets of improving flower life. This critical information was developed with the support of the American Floral Endowment and many other trade associations. Currently, their findings are known throughout the industry as the best methods for improving postharvest quality, and this acclaimed body of work forms the bulk of the newest edition of the SAF Plant and Care Manual, published by the Society of American Florists.
The study met and assured many challenges, but raises the “chilling” question: with these past secrets unlocked, will “you” the floral consumer, demand for your flower purchases proper care-and-handling procedures?
The American Floral Endowment has been the leading not-for-profit organization in the floriculture industry for over 40 years. Its mission is to fund research and educational programs that foster a stronger floriculture industry. Tax deductible contributions from all segments of the industry have enabled the Endowment to invest over $9 M, helping to unlock other key secrets that have enabled the industry to prosper. For additional information regarding the Endowment’s scientific research program, the Consumer Tracking Study, or any of its educational programs, please contact the Endowment office or visit the web site: www.endowment.org.
