Chapter 10 Care and handling.
Directly influenced by genetics, the longevity of flowers varies greatly among genera. Longevity even varies among cultivars of the same species. Generally, stem diameter and stiffness are factors in the length of a flower's cut life; thicker stems prevent bending and breaking and contain more stored nutrients for flowers, increasing their longevity.
Genetic factors aside, there are several common reasons why flowers wilt and die prematurely. They include the inability of stems to absorb water, lack of carbohydrates, excessive transpiration, bacterial growth and disease, ethylene gas, and improper surrounding conditions. In order to counteract these situations detrimental to flowers, a knowledge and understanding of care procedures necessary for extending longevity and delaying senescence, or death, is essential.
Care and handling refers to all procedures that are done to help cut flowers and foliage last longer. Florists can do much to extend the life of cut flowers, thus extending satisfaction and enjoyment of flowers for the final consumer (see Figure 10-1).
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Chain of Life
The chain of life is a postharvest care program now under the direction of the Society of American Florists. The postharvest period for cut flowers, when thought of as a chain, can be separated into links, or steps of distribution (see Figure 10-2). The steps of distribution, or the links of the chain, include the grower, transporter, wholesaler, retailer, and final consumer. When the postharvest period is divided into steps, each level of distribution may be better analyzed regarding care and handling techniques necessary for extending longevity.
Strengthening each link by looking at sanitation, preservatives, water quality, temperature, and humidity, as well as other factors, is the goal of this program, thereby giving the entire chain more vitality and endurance. The chain of life program, based on facts derived from scientific research rather than on hearsay and myth, requires a cooperative effort by each vital link. The cliche "a chain is only as strong as its weakest link" reminds floral distributors and designers that a combination of proven techniques at each level of distribution is necessary for promoting the longevity and beauty of flowers.
Initial Procedures to Delay Senescence
The initial treatment of fresh flowers at each level of distribution is referred to as processing (see Figure 10-3). These first care procedures, whether at the wholesaler or retailer or in the home, are vital for ensuring lasting quality of flowers. Caring for flower stems by recutting them and removing lower leaves and any damaged parts are prerequisites to later treatments involved in the entire postharvest care program. (For specific information regarding the harvest, storage, and transportation of commercially grown cut flowers, see Chapter 20.)
Recut Stems Prior to Conditioning
As mentioned previously, the inability to absorb water is typically the reason that cut flowers wilt and die prematurely. A new cut at the base of the stem opens up the water-conducting vessels of the xylem, which close due to stem blockage.
Stem blockage, or plugging, is the result of air, debris, healing from the original or earlier cut, and the growth of microorganisms at the base of the stem. Air embolism occurs when small bubbles of air, called air emboli, are drawn into the stem at the time of cutting. These bubbles cannot move far up the stem, so the upward movement of solution to the flower is restricted. Microorganisms present in water enter the base of the stem causing plugged vessels. If flowers do not receive a fresh cut, vase life will be drastically reduced because the clogged flower stems physically cannot absorb the necessary water and nutrients to keep them turgid (firm) and healthy for as long as possible.
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The initial stem cuttings by the wholesaler, retailer, or final consumer, should be done under water to prevent air from entering the xylem (see figures 10-4 and 10-5). Existing emboli can be removed by recutting the stems under water. As shown in Figure 10-5, water droplets will adhere to the freshly cut stem ends as they are removed from the water in which cuttings are made and moved to another container of water. These water droplets, in essence, seal the stem ends and prevent air from entering.
Cutting stems under water is especially important for flowers that are severely water stressed or wilting to help them regain turgidity quickly. Also, if flowers have been out of water for an extended period of time, under water cutting ensures stem blockage removal and rapid water uptake. Cutting stems under water will also accelerate the conditioning process, as well as open flower buds more quickly.
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To cut flowers under water, fill a bucket, sink, or commercial underwater cutter with warm water. If you are cutting several flower stems or an entire bunch at once, make sure stem ends are all the same length so that each will receive a cut. Hold the flowers at an angle so the lower part of the stems are submerged. Cut off the lower 1/2 to 1 inch of the stem.
It is helpful to recut flowers every two or three days to open the water-conducting vessels. Once flowers have been properly processed and are full of water at each step throughout the chain of life, other cuttings do not necessarily need to be made under water, unless flowers become limp and wilted.
It has long been thought that woody stems drink up water faster if they are pounded with a hammer, but this action has been proved ineffective. A better practice is simply to recut woody stems more frequently than herbaceous (nonwoody) stems. Never mash, shred, or split stems in any way, as these practices can easily damage vessels that carry water and nutrients.
Remove Excess Foliage
Excess foliage that will be below the water level should be removed from the stems, as shown in Figure 10-6. If left on the stem, the soggy foliage decomposes, increasing the growth of microorganisms and the production of ethylene. The water becomes filthy and odorous, and the stems and container become slimy with the bacterial growth. The bacteria then lodge in the stem ends, clog the vessels, and impede water uptake. All this leads to the early senescence of flowers.
In removing excess foliage, it is important that you do not scrape the stems. Gently pull the leaves down and off or use clippers or a stripper tool. (Removing leaves with a knife may injure tender bark.) Automatic strippers are available for larger floral operations. These machines have rotating rubber fingers that remove leaves quickly and gently.
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Most roses have thorns that can damage tender petals and foliage. Once a thorn has punctured into an adjacent rose head or other flower, the puncture wound usually goes through many layers of petals. Removing sharp thorns will prevent this damage from happening and allows for easier handling of flowers. To remove thorns, it is best to just remove the thorn tip. The use of a hand stripper is more efficient than that of a knife or clippers (see Figure 10-7). When using a hand stripper, be careful not to scrape or scar the stems. It is not necessary to completely remove entire thorns right down to the bark. This action can damage stems, allowing bacteria to move into the newly formed scars where thorns have been. Instead, just dull the thorns by removing their sharp points.
Specialty Treatment for Stems with Latex Sap
A few flowers and foliage, when cut, bleed latex, a white milky sap. Flowers and foliage with this milky sap will wilt rapidly if not properly cared for since the latex, which is made up of resins and proteins, reseals the cut surface and blocks water uptake. It is, therefore, necessary to open up the water-conducting vessels and at the same time stop the bleeding sap. There are several treatments that may be done to open the water-conducting vessels while sealing the latex.
Many flower varieties of today do not warrant searing or scalding the stems to stop the milky latex from bleeding. However, some latex is still present and must be properly cared for. For these newer varieties, research has proved that simpler methods help to keep the stem clean and open for water absorption. Just cutting the stems and placing them in floral preservative for a few hours or overnight will benefit these flowers (see Figure 10-8). Or use two teaspoons of 10 percent liquid chlorine bleach per gallon of water to stop latex excretion for some flowers.
Time-honored techniques used for flowers that rapidly excrete excessive latex and will not stop bleeding with other treatments include the use of heat (boiling water or a flame) as shown in Figure 10-9. To seal the latex, immediately after recutting the stem, dip the stem ends in boiling or very hot water for a few seconds, and then transfer the stems to preservative solution. Or singe individual stem ends with a flame by holding the stem at an angle and passing a flame beneath the newly cut stem, which sears the latex. These singed stems should also be placed in preservative solution.
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Sealing the sap of stems that bleed latex--such as poppies, poinsettias, and flowering spurge--helps prevent unsightly discoloration of the water and lengthens postharvest life.
Wilt-Sensitive Flowers and Foliage
Some flowers and foliages are wilt sensitive, that is, they wilt easily and transpire rapidly, resulting in lost turgidity (see Table 10-1). In dry air, or when left out of water even for a short time, these flowers and foliage have a tendency to become limp quickly. Many are prone to drying (dry prone), causing shedding of florets and leaves. It is important for you to know which flowers and foliage are wilt sensitive, so that you can give them priority when processing many types of flowers and foliage. Many of these flowers and foliage benefit from misting. (See the appendixes for specific flower and foliage care.)
Reviving Wilted Flowers and Foliage
Many flowers and foliage can be revived after being out of water for an extended period of time or if they show signs of water stress and become limp and wilted. To revive flowers and foliage, soak the entire flower (stem and head), foliage stem, or single leaf by submerging it in room-temperature water for five to fifteen minutes or longer (see Figure 10-10).
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Many tropical flowers benefit from soaking. Some examples include anthurium, ginger, bird of paradise, and heliconia. After soaking these, make sure that water does not collect on or in the enclosed flower parts; as this can cause rotting.
Some foliage that is easily revived by soaking include Boston fern, galax, ivy, oregonia, and boxwood. Soaking brings new life to this foliage.
Recut Stems Prior to Design Work
When recutting flower stems as you make arrangements, use sharp, quality tools; never use scissors or dull knives to cut flowers (see Figure 10-11). Tearing, breaking, snapping, or smashing stems will decrease the life of flowers by damaging water-conducting vessels. Do not use scissors because they tend to pinch stems and actually can constrict xylem vessels and keep them from absorbing maximum water.
Many designers prefer using knives over clippers; when using a knife, while holding the stem of the flower in one hand and the knife in the other, pull the knife quickly through the stem to form a slanted cut, keeping your thumb and fingers out of the path of the knife blade (see Figure 10-12). After some practice, you will find that using a knife as you do design work will become easier and more efficient than using clippers.
The proper temperature and quality of water are both important considerations that can increase the longevity of cut flowers. Not all water is equally suitable for flowers. The quality of water is determined by various characteristics, such as pH level and the amount of minerals and impurities present. These can drastically influence cut flower quality and the effectiveness of commercial floral preservatives.
As stems absorb water, they also drink in entrapped air. It is best to use warm water (100[degrees]F to 110[degrees]F), because it contains less air than cold water; warm water with less oxygen reduces the potential for air blockage. Warm water also is preferred because it flows more readily into the stem than cool or cold water. Treatment with warm water is especially beneficial for flowers that are slightly wilted. Never use hot water, which essentially cooks or scalds the stems. If you are unsure how warm (110[degrees]F) water feels, use a thermometer to determine the correct temperature (see Figure 10-13).
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Cut flowers need clean, pure water. Tap water often contains injurious chemical compounds and varies in pH level; it also contains organic matter and microorganisms that may prove to be detrimental to flowers. For instance, certain ions found in tap water are toxic to some cut flowers. Sodium, present in high concentrations in soft water, is toxic to carnations and roses. Another example is fluoride, which is often added to drinking water. Fluoride is extremely toxic to gerbera, gladiolus, freesia, and some roses, and will cause damage to these cut flowers. The differences in tap water influence the longevity of the flowers as well as the efficiency of chemical solutions used.
Several aspects of water quality should be considered. These include pH level, hardness, alkalinity, and the amount of total dissolved solids (TDS).
A pH level denotes the relative concentration of hydrogen ions in a solution. The letters pH come from the French words pouvoir (power) and hydrogene (hydrogen), literally meaning hydrogen power. On a pH value scale from 1 to 14, the lower the value, the more acidic the water, or the more hydrogen ions it contains. A pH of 7 is considered neutral, and a pH higher than 7 is alkaline, meaning that it contains fewer hydrogen ions.
The ideal pH solution for flowers, after water is mixed with floral preservative, is 3.0 to 4.5. Acidic solutions (containing more hydrogen ions) have better cohesive qualities and move more readily into and through stems than neutral or alkaline solutions. Microbial growth is also limited in solutions that are acidic.
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Hard Water and Alkalinity
Hard water has a high mineral content, specifically magnesium and calcium. The level of hardness refers to the amounts of these dissolved salts in the water. Hard water generally leaves white, crusty deposits when it evaporates from a surface. This type of water often produces dismal results for flowers.
However, softened water should not be mixed with hard water in an attempt to counteract water hardness. Softened water does more damage to certain flowers than hard water, since water softeners add salts (usually sodium) to the water. If hard water is the only option in your city, you can increase flower longevity by using distilled or purified water.
Hard water contains minerals that make the water alkaline. Alkaline water does not move readily through stems and can substantially reduce vase life. The alkalinity of water refers to the measure of its capacity to neutralize acids and resist chemical changes; this is also its buffering capacity. Water with high alkalinity is highly buffered and resists any efforts to change pH when floral preservative is added specifically to lower pH. Alkaline water can be treated by removing the minerals using a deionizer or by adding enough acid to acidify the water.
Total Dissolved Solids
Total dissolved solids (TDS) refers to the measurement of water salinity (salts) or total dissolved solids or soluble elements in the water. Some of these dissolved solids include salts from calcium, magnesium, sodium, chlorides, carbonates, and sulfates. A TDS reading is usually in parts per million (ppm). High-quality water for cut flowers should have less than 200 ppm. Higher TDS levels generally prove to be detrimental for many cut flowers.
To ensure that you are doing the most for your flowers, have the water in your area tested. You can test the water frequently yourself by using a pH meter and TDS meter. These handheld meters are available in a number of different models and sizes. They are generally available for purchase from laboratory or greenhouse supply companies.
For a water analysis, contact a reputable water treatment company. There are also many laboratories that will run the tests you need. Once you receive the results of the water analysis, most floral preservative companies will evaluate it at little or no charge, revealing the overall quality of the water as it relates to cut flowers.
In most cases, all that is needed to improve water quality is the addition of the correct amount and kind of commercial floral preservative. In extreme cases, for wholesale or retail operations, for instance, it may be suggested that a water purification system be used.
Chemical Solutions and Procedures
Several chemical solutions and procedures are used to improve the longevity and quality of cut flowers. Some of these procedures are done by the grower shortly after harvest and before the shipping or storage of flowers. Others may be done at the wholesale or retail level before or after shipping. Several considerations are important in deciding which treatments are necessary, including the genus or species and the overall quality of the flowers, the length of time the flowers are at each level of distribution, and if any prior treatments have been done.
Several chemical solutions are used to extend vase life and increase the quality of cut flowers. The use of floral preservatives is a long-term solution, that is, they should be used at every level of distribution during the entire postharvest period. The pretreatments of silver conditioning and citric acid, as well as the procedures of pulsing, hydrating, and bud opening are short-term solutions, that is, used for a short time at one or more levels of distribution. The different solutions in which flowers may be placed after harvest have specific objectives.
You may remember a time when the vase water holding a bouquet of flowers turned murky and smelled awful; and after tossing out the wilted flowers and disgusting water, the vase and stems were slimy. The use of floral preservatives greatly inhibits unpleasant, odoriferous situations like this.
Commercial floral preservatives are chemical mixtures, added to the water, that extend the vase life of flowers. Preservatives literally preserve the quality of postharvest life by prolonging vase life, increasing flower size, and maintaining the color of petals and leaves.
Floral preservatives should be used during the entire postharvest period --by the grower, wholesaler, retailer, and final consumer--during which time flowers at all levels will benefit from the action of preservatives. Whenever plain water can be absorbed by flowers, use instead preservative solution. For instance, flowers in storage will benefit greatly from the use of preservatives. And when designing with flowers, use preservative solution to soak floral foam and add it to all designs, including bud vases and foam arrangements. Flowers in water tubes benefit greatly from the use of preservative solution as well.
When mixing commercial floral preservatives, whether liquid or powder, always follow the directions on the label or package. Avoid the use of metal buckets and containers; metal containers react chemically with the acidifiers in the preservative, rendering them ineffective. Generally, metal buckets and containers experience some corrosion as well. The correct concentration is important, as is a thorough mixing. A lump of preservative powder can easily plug water-conducting vessels, thus inhibiting water uptake.
The combined ingredients in floral preservatives all work in harmony to maintain quality and extend the postharvest period. Three primary components of preservatives are sugar (carbohydrates to nourish), biocide (inhibits the growth of microorganisms), and an acidifier (lowers pH levels). Secondary components included in some preservatives are growth regulators (to increase the vase life of some flowers) and wetting agents (to aid in water absorption).
Sugars. Sugars are the main source of nutrition for flowers. Plant tissues require sugar in order to carry on vital functions, especially respiration. Normally, the process of photosynthesis supplies sugars to the plant tissues both for growth and metabolic activities. Once a flower is cut, the process of photosynthesis, through which the flower obtains most of its energy, is temporarily stopped. Although starch and sugar stored in the stem, leaves, and petals provide much of the food needed, cut flowers continue to need energy in order to open up and develop to their full potential. So it is necessary to supply an alternative source of energy with the addition of sugars or carbohydrates.
Carbohydrates support the metabolic activities that continue during the postharvest period. Simply put, these sugars, such as sucrose and dextrose, provide food for flowers. Concentrations of sugars needed by cut flowers vary with species. All sugars present in water, however, create excellent conditions for the growth of detrimental fungi and bacteria, the growth of which can be enhanced by organic materials from the cut stems. Substances produced by the bacteria, and the bacteria themselves, plug the water-conducting vessels of stems. For this reason, buckets and containers should be cleaned and disinfected regularly, and the water solution should contain biocides to prevent the growth of microorganisms.
Biocides. A biocide or germicide is a chemical substance that can kill living organisms, especially microorganisms. Microorganisms that grow in the vase water include bacteria, fungi, yeasts, and molds. Through their development and the eventual blockage of the xylem, these are harmful to cut flowers (see Figure 10-14). Water and carbohydrates are physically prevented from getting into the flower. These microorganisms also produce ethylene and toxins, which speed up flower senescence.
Several biocides are used in commercial preservatives to inhibit the growth of microorganisms, including 8-HQC (8-hydroxyquinoline citrate), 8-HQS (8-hydroxyquinoline sulfate), Physan-20 (an ammonium compound), silver nitrate, and household bleach. These are all used in extremely small amounts.
Acidifiers. Commercial floral preservatives also contain acidifiers for reducing the pH level of water. As mentioned previously, the pH is the measure of acidity or alkalinity of water or other solutions. The ideal pH level for preservative solutions for cut flowers is 3.0 to 4.5, which maximizes water uptake so that stems become hydrated (full of water and preservative) more easily.
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The most effective acidifier in preservatives is citric acid. Another highly effective acidifier is aluminum sulfate, which has proved to be especially helpful in water that is high in salts. Both are used in extremely small concentrations.
Growth Regulators. Some preservatives contain growth regulators, namely cytokinins. Cytokinins are plant hormones that stimulate and promote cell division. When absorbed by stems, ctyokinins greatly extend the postharvest period and help maintain pigment colors, especially chlorophyll, preventing yellowing in the leaves and stems of some cut flowers and foliage. The growth regulator that is most common in commercial preservatives, increasing vase life, is 6 benzyl adenine.
Wetting Agents. Chemicals used to increase the ability of water to be absorbed by flower stems, or wetting agents, are often an ingredient in floral preservatives. These help make the water "wetter," accelerating the uptake of water. These chemicals, such as sodium hypochlorite, are used in extremely small concentrations.
Throughout the years, many household products and chemicals have been used in an effort to increase the vase life of cut flowers. Today, we have products that are manufactured to do just that: increase not only the length of the vase life, but the overall quality of the flowers as well. There are many who swear by the use of certain household chemicals as home remedies for extending the life of cut flowers. Some actually work, others do not, and still others may be harmful to cut flowers.
There are two products that have proved beneficial when diluted with water--lemon-lime soft drinks and medicinal-type mouthwash. Remember to use these products at home only when no commercial preservative is available.
Adding a lemon-lime soft drink to water can extend the longevity of flowers. Any brand of lemon-lime carbonated drink will work, with the exception of diet varieties. Be careful, however, to use a variety that is clear and cannot be seen; some sodas are yellow or yellow-green and are visually unappealing in a clear vase. The lemon-lime soda pop contains citric acid and carbonation, both bactericide. This helps allow the sugar content of the drink to be used by the flower without an increase in microorganisms in the short term. However, the carbonation quickly dissipates, making the citric acid level relatively low. The microbial activity will then increase rapidly. The positive effects will last one to two days. Ratio will depend on the flowers--some studies show one part soda to two parts water, others recommend diluting further: one 12 ounce can to one to three gallons of water.
Another product that helps extend the longevity of cut flowers is mouthwash. The medicinal types of mouthwash have proved most effective. The ingredients in mouthwash, which kill germs and bad breath, will act as an effective bactericide when added to the water. Use only a small amount, about 2 tablespoons per gallon of water.
The addition of other home remedies--table sugar, pain killers, pennies, or bleach--to the water has proved ineffective. Commercial floral preservatives are more reliable in extending the life of cut flowers.
One of the worst things you can add to the water is plain table sugar. When sugar is added to the water for cut flowers the bacteria in the water quickly grow out of control within a few hours. Rather than the sugar providing energy and food, as we like to think, it clogs and plugs the stems, and flowers will wilt and die prematurely.
Many have long felt that aspirin or other pain killers, when crushed up and added to the water could help flowers. However, the effect aspirin has on the quality and length of vase life is minimal. Aspirin may have negative effects due to the additives in some brands. The minimal positive effect from aspirin is the salicyclic acid, which may lower the pH level slightly, helping to hydrate flowers a little more quickly.
Pennies may have been somewhat helpful in extending the vase life of flowers when they were made entirely of copper. When these pennies were added to water, slight oxidation of the copper resulted in cupric oxide, which acts as a mildly effective bactericide. Today, pennies contain very little copper and the rate of oxidation is so slow that when they are added to the water, there is basically no effect.
Bleach is definitely a strong bactericide. However, to most cut flowers it is extremely harmful. The use of bleach in the water to help flowers is unreliable and chancy. Whether the addition of bleach will help control the bacteria or will be toxic to flowers is obscure, and so it is best to use bleach only for sanitation efforts--to wash buckets, containers, and tools.
Remember, though, it is more beneficial to use time-tested commercial preservatives because they contain the most effective combination of ingredients for extending the life of cut flowers.
Pretreatments are special care treatments used prior to floral preservatives that help to extend the life of cut flowers. Common pretreatments include silver conditioning, EthylBloc, or other anti-ethylene products, which greatly inhibit the action of ethylene in many flowers, and citric acid conditioning, which hydrates flowers quickly. Other names for pretreatments are supplements, special treatments, specific-action chemicals, and conditioners.
Anti-Ethylene Treatment. A postharvest process carried out for ethylene-sensitive flowers and referred to as pretreatment (procedure used prior to floral preservative), these conditioning treatments help protect flowers, such as carnations, gypsophila, lilies, alstroemeria, snapdragons, and dendrobium orchids against the irreversible effects of ethylene, therefore increasing their postharvest period (see Figure 10-15).
Silver thiosulfate (STS) is a compound of silver that is readily absorbed into flower stems. Flowers should be treated with STS only one time during postharvest life. The most effective time for silver conditioning is shortly after harvest, administered by the grower (because of environmental concerns about silver contamination and proper disposal, the STS treatment is no longer legal in the United States, but flowers that are treated with STS in foreign countries may still be imported into the United States). The process of silver conditioning is similar to the use of a floral preservative; flower stems must be processed first. Next, the newly cut stems are immediately placed in an STS solution and left to condition at room temperature for one to two hours, depending on label directions. The flowers should then be placed in a preservative solution (without recutting stems) and transferred to the cooler.
EthylBloc is a trade name for 1-methylcyclopropene (1-MCP) which is a gas in its natural form. EthylBloc is a powder that when mixed with water, releases a non-toxic gas that blocks the detrimental effects of ethylene. Because 1-MCP is a gas, treatment must be carried out inside a sealed space, such as in a sealed truck during transport or in a sealed floral cooler overnight during storage.
Citric Acid. Citric acid treatment, like silver conditioning, is a pretreatment, administered before the use of floral preservative. This procedure, also called hydrating, is a short-term technique that restores flowers to a visibly turgid condition by expediting water uptake. Generally, hydrating is done before or after dry storage and shipping. Carried out by the grower, the wholesaler, or the retailer, the hydrating process takes a few seconds to one or two hours. Hydrating solutions contain acidifiers (to obtain an optimum pH level) and wetting agents. Combined with warm water, newly cut stems absorb water quickly.
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Roses, gerberas, and chrysanthemums benefit greatly when pretreated with a citric acid solution, which prevents the growth of microorganisms and keeps the water-conducting vessels of the xylem open for easier transport of water and nutrients. Citric acid treatment speeds the intake of water, helping to prevent bent neck in roses and gerberas (see figures 1016 and 10-17).
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Citric acid treatment is accomplished by dipping or placing newly cut (under water) stems in the solution, at room temperature for one to four hours (depending on the manufacturer's directions). Then the flowers are placed in a preservative solution (without making new stem cuts) and transferred to the floral cooler. Other solutions are available in which the bases of flower stems are quickly dipped in higher concentrations of citric acid for one or two seconds, then immediately placed in a floral preservative solution. Citric acid pretreatments can be used at all levels of the floral industry, by growers, shippers, wholesalers, and retailers.
After pretreatments are complete, flowers should be conditioned with other chemical solutions, namely, floral preservatives. Depending on the level of distribution, the type of conditioning will vary; the flowers may need to be made ready for dry-packing for transportation in boxes, or they may need to be stored in a cooler, or the flower blossoms may need to open and mature quickly for use in arrangements. Common treatments include conditioning, pulsing, and bud opening solution treatments.
The process of conditioning allows flower stems to remain in a warm preservative solution for a period of time before being placed in a floral cooler. Most flowers will absorb a maximum amount of preservative solution in one or two hours; for extended conditioning, flowers may remain in the solution overnight. Conditioning speeds the opening of tight flower buds (for example, gladiolus, lilies, carnations, and alstroemeria), helping them to reach optimum beauty. Conditioning is done at all levels of the floral marketing chain.
Most flowers may be conditioned together with other flowers, with the exception of daffodils (Narcissus), which should always be put in separate buckets because they produce a sappy secretion that flows from the stem ends after they are cut. The sap is harmful to other flowers, especially tulips. Once daffodils have been conditioned in a preservative solution for six to twenty-four hours, they may be mixed with other flowers. However, do not cut them again after this conditioning process.
After flowers have been conditioned at room temperature and are fully turgid, these buckets, or holding containers, should be transferred to a floral cooler where the stems can become firm and solid. This process is called hardening and is done at the grower, wholesale, and retail levels of distribution.
Pulsing is a postharvest technique used to load or fill flowers with sugar and other chemicals, giving them "strength" before they are dry-packed and shipped long distances. Pulsing is usually performed at the grower level and sometimes at the wholesale level. Not all flowers respond equally to pulsing solutions. Sucrose is the main ingredient of pulsing solutions, generally 2 percent to 20 percent or more sugar (depending on the flower). A biocide to help keep flowers healthy by inhibiting the growth of microorganisms is also used. Some cut flowers are pulsed with STS to reduce the effects of ethylene. Flowers can be pulsed for short periods at warm temperatures, such as ten minutes at 70[degrees]F, or long periods at cool temperatures, such as twenty hours at 36[degrees]F. Some crops, such as China aster (Callistephus), Gerbera, and maiden hair fern (Adiatum) respond well to short ten-second pulses in solutions of silver nitrate.
Bud Opening Solution
Bud opening procedures are generally intended for flowers that are harvested at an immature stage and would otherwise not open up to their full potential and optimum beauty. These solutions contain a biocide and sugar. Buds should be opened in an environment of high relative humidity (60 percent to 80 percent), warm temperatures (70[degrees]F to 80[degrees]F), and with high light intensity. Tight flowers may be placed in bud opening solutions until buds begin to open on their own or until flowers are at the desired maturity stage. This procedure may be done at the grower, wholesaler, or retailer.
After flowers are cut, and before they are enjoyed by the final customer, they are kept refrigerated for much of the time. Proper refrigeration is essential for increasing the overall storage and vase life of cut flowers and foliage (see Figure 10-18).
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The three main functions of refrigerated storage for fresh flowers are (1) to reduce the rate of respiration, (2) to reduce water loss or transpiration, and (3) to reduce the rate of bacterial growth and ethylene production and action. Refrigeration removes heat that flows naturally from flowers and slows respiration, or the breakdown of food. It keeps flowers at their peak longer by delaying further development and bud opening. It also decreases the rate of transpiration or water loss in flowers. Because water loss is reduced, flowers remain fresh and turgid, or full of water. In addition, the growth of bacteria is slowed and the production and effects of ethylene are reduced as the temperature in refrigerated storage is lowered, dramatically decreasing the deterioration of flowers.
Although these functions of refrigerated storage all help extend quality and longevity of fresh-cut flowers, a combination of both correct temperature and humidity is required to maintain flowers at optimum conditions. Other factors such as ventilation and lighting are also important considerations for keeping flowers in refrigerated conditions.
The goal of refrigeration is to store flowers at the lowest temperature possible without causing the flowers to suffer cold damage or, worse, to freeze. The ideal storage temperature for most cut flowers is 32[degrees]F to 36[degrees]F. The species of flowers as well as the length of time the flowers will be in refrigerated storage will dictate the correct temperatures. The optimum temperature for storage of most common cut flowers is 32[degrees]F (when stored for more than two or three days). Flowers kept in refrigerated storage for a period of less than two days can be maintained satisfactorily at 34[degrees]F to 40[degrees]F.
Small changes in temperature greatly alter the quality of flowers by influencing the metabolic reactions within the flowers. It has been shown that flower deterioration increases two to five times faster for every increase in temperature of 15-18[degrees]F above optimum refrigerated storage conditions.
Freezing of flowers may result if the temperature in a cooler drops below 32[degrees]F. Freezing injures cut flowers by causing ice crystals to form in stems, leaves, and flowers; these ice crystals puncture the cell walls of these various plant parts. When flowers thaw, tissues appear water-soaked, translucent or discolored, and soft.
Many tropical and subtropical flowers are sensitive to low temperatures and should not be stored in a regular floral cooler with other flowers. These flowers are subject to chilling injury at temperatures below 50[degrees]F. Symptoms of chilling injury include darkening (browning, blackening, and lesions) of the petals, water-soaking of the petals, and sometimes collapse and drying of the leaves and petals. Table 10-2 lists common tropical and subtropical florist flowers that are subject to damage if temperatures are too low. These flowers store best in a warmer environment at 50[degrees]F to 60[degrees]F.
Low temperatures must be combined with humidity for increased flower longevity.
Humidity refers to the amount or degree of moisture in the air. Relative humidity is the amount of moisture in the air as compared to the maximum amount that the air could contain at a certain temperature. Cold air holds less moisture than warm air. Humidity during refrigeration is essential for cut flowers and foliage, and without it at low temperatures, flowers and foliage dehydrate rapidly. After proper hydration, flowers remain turgid in cold, humid conditions; as the result of lowered transpiration, less water is lost from the flowers.
The recommended percentage of relative humidity for a refrigerated storage unit is a minimum of 80 percent. Many flowers last longer, however, with a 90-95 percent humidity level. If the humidity level is too high (especially if temperatures are above 40[degrees]F) or if temperatures fluctuate, condensation may form on the petals and this moisture may lead to the consequent growth of botrytis and other pathogens.
Ventilation and Lighting
Other considerations such as ventilation and lighting are important for maintaining the quality of flowers. Ventilation, or air flow, is essential while flowers are refrigerated. Some ventilation is necessary for removing excess heat that may have built up in the flowers. The circulation of fresh, cool air at a low speed in a gentle stream will allow the flowers to remain cool and avoid drying up.
Lighting is essential for flowers while in refrigeration. High-intensity lamps that stimulate natural sunlight help flowers maintain the photosynthetic processes and their colors will remain more accurate.
Ethylene is naturally produced by cut flowers and foliage, ripening fruits and vegetables, and decaying and wilting plant tissues. Other sources contributing to high ethylene levels include exhaust, smoke, pollution, and bacteria. Ethylene-induced disorders account for a high percentage of flowers dying prematurely.
Effects on Flowers
The general symptoms of ethylene on flowers include buds and flowers failing to open, as well as the closing of open flowers, and overall sleepiness or a wilted appearance. Some flowers, especially carnations and some roses, perish rapidly if exposed to minute concentrations of ethylene and become wilted and limp. In many inflorescence types, such as snapdragon, delphinium, and larkspur, ethylene causes flower abscission, or shattering, and florets fall off easily. Levels of ethylene in the air above one-tenth part per million (0.1 ppm) surrounding most cut flowers can cause damage. Color is dramatically affected and many flowers quickly fade when ethylene is present.
[FIGURE 10-19 OMITTED]
The effects of ethylene cannot be reversed, but the amount of ethylene present in the atmosphere surrounding fresh flowers and foliage can be minimized by avoiding sources of ethylene, reducing ethylene production, and inhibiting its action.
Reduction and Control
It is impossible to eliminate all sources of ethylene, but some sources are relatively simple to avoid. When certain flowers begin to deteriorate sooner than others, it is important to remove them from the floral cooler or from floral arrangements (see Figure 10-19). Their increased production of ethylene will accelerate the aging process in the surrounding flowers. Remember also that almost any exhaust or smoke is detrimental to fresh flowers. Keep apples and other fruits, vegetables, and food away from fresh flowers.
Ethylene production can be minimized best by keeping floral areas and equipment clean. It is essential that buckets, containers, tools, water, and design and storage areas are kept clean and sanitized with a disinfecting agent on a regular basis. Adding fresh flowers to slimy buckets or containers will further the growth of bacteria and increase the production of ethylene. Storage and handling areas should provide ventilation to remove ethylene that does occur.
Inhibiting the action of ethylene is all important. Some flowers are much more sensitive to ethylene. Chemical treatment with STS, EthylBloc, or other anti-ethylene products to inhibit the action of ethylene and reduce the effects of ethylene (both exogenous and endogenous) is extremely beneficial for some flowers. These treatments dramatically increase the vase life of ethylene-sensitive flowers by providing protection against the effects of ethylene. Refrigeration greatly reduces ethylene production and the sensitivity of flowers to ethylene. Table 10-3 lists flowers that are ethylene sensitive.
Care and Handling of Garden Flowers
Many flowers grown in a garden make excellent cut flowers, giving floral bouquets a casual, country look (see Figure 10-20). If you have the space and time, growing a flower garden can provide a wonderful array of bright and unique flowers that can be used alone or with commercially grown flowers. As with flowers that are commercially grown, it is important to follow proper harvesting, care, and handling techniques so that maximum vase life can be enjoyed.
Harvesting Garden Flowers
Time of Day
Gather garden flowers only in the early morning or in the evening, because flowers in the morning or evening are more fully turgid and contain higher carbohydrate food reserves (see Figure 10-21). Never cut garden flowers during midday or in the late afternoon. Weakened by the heat of the day, flowers are less turgid and contain fewer carbohydrates. Flowers that are cut in the afternoon have a much shorter vase life than those cut in the morning or evening. They never gain full turgidity and usually appear limp and wilted, even after following postharvest care and handling techniques.
[FIGURE 10-20 OMITTED]
[FIGURE 10-21 OMITTED]
[FIGURE 10-22 OMITTED]
Stage of Flower Maturity
Use sharp clippers or floral shears to cut flowers from plants that are robust and healthy. Choose flowers that are at the correct stage of bud development. If flowers are harvested too early, they usually will not open fully and will soon wither and die with the buds still closed. However, other flowers when cut fully opened, start to fade and drop petals quickly. With some practice, you will know when to cut garden flowers for maximum vase life.
Garden flowers can be grouped into three stages of bud development for cutting: bud stage, half-open bud stage, and fully open bud stage (see Figure 10-22).
Flowers that should be cut when they are still buds are generally those that are solitary. Examples of these flowers include roses, peonies, daffodils, irises, and tulips. These single flowers usually continue to open and develop after cutting. Therefore, the use of floral preservative is essential to provide these flowers with more carbohydrates, giving them energy for the buds to open up.
The half-open bud stage is a general description for spikelike flowers and racemes that have a number of florets per stem. Other inflorescence types like umbels, corymbs, and many panicles are also best cut at the half-open stage. These flowers are best cut with about half of the florets on the stem open and the other half still in the bud stage. Since florets continue to open, these flowers will extend the life of a floral arrangement. Examples include gladiolus, delphinium, larkspur, eremurus, and snapdragon. Examples of umbels and other inflorescence types with more than one floret per stem include agapanthus, nerine, alstroemeria, lilies, and phlox.
Some flowers are best cut when fully open before they shed their pollen. Once cut, they do not continue to open to their full potential. Many of the head flower inflorescence types are best cut when fully open. Examples include sunflower, zinnia, aster, chrysanthemum, dahlia, marigold, and calendula.
Care and Conditioning
When you gather flowers, take a bucket of warm preservative solution with you out to the garden. As you cut your flowers, immediately place the stems into the preservative solution. Never place harvested flowers on the ground where they may become contaminated with disease organisms.
Take the cut garden flowers indoors, recut the stem ends underwater, and allow them time to drink in the preservative solution for at least two hours or, better still, overnight before using them in designs. This time is needed for sufficient conditioning.
Garden flowers, like commercially grown flowers, should have lower foliage removed from stems that will be in water. Remember specialty treatments as well, such as conditioning daffodils by themselves and sealing the latex of poppies.
Garden flowers should be used as soon as possible after a conditioning period rather than storing them in a floral cooler. With planning and proper postharvest care, most cut garden flowers will last five to ten days. Table 10-4 lists easily grown garden flowers that are medium- to long-lasting cut flowers.
Forcing Flowering Branches
Branches from deciduous shrubs and trees may be forced to bloom beginning in January, after they have experienced cold winter temperatures. Attempts earlier than January 1 usually fail because dormant buds have not had enough cold temperature. After this cold requirement has been met, budded branches may be cut from outdoor plants and forced to flower indoors (see Figure 10-23).
[FIGURE 10-23 OMITTED]
After cutting woody branches, take them indoors. Recut again under water and then place stem ends in warm preservative solution. The length of time from cutting to flowering depends on the variety of the flowering branch being forced, the temperature, and when the branches are cut. Warmer temperatures of air and water will hasten flowering. Colder temperatures delay blossoms. The later in the season the branches are cut (that is, the closer to natural flowering patterns), the less time is required to force branches into bloom. Generally, forcing will take place in several days to several weeks. It is essential during the forcing period to replenish and change the preservative water as well as to recut the stems underwater every two or three days. Table 10-5 lists proven favorites for bringing forth an early spring.
Care and Handling of Floral Arrangements
[FIGURE 10-24 OMITTED]
Flowers in arrangements will last longer, as a whole, if they are given continued care in the home (see Figure 10-24). Care tags should be attached to bouquets to educate the final consumer on how to care for arrangements to increase longevity and enjoyment. The water level in the container should be checked once or twice a day and replenished with warm preservative solution. Periodic misting of floral arrangements is beneficial. Misting helps maintain the turgidity of flowers and foliage. For best results, spray gently with a spray bottle. If one or two of the flowers become wilted or limp within the arrangement, remove them from the bouquet, recut their stems underwater and immerse them in warm preservative solution. If these flowers revive, replace them in the bouquet. If they do not, discard them.
Keep floral arrangements away from ethylene sources including cigarette smoke, exhaust, and ripe fruits and vegetables. Also, remove flower heads as they die to keep a floral arrangement looking attractive for a longer period of time.
Floral arrangements will last much longer if kept out of direct sunlight and off of warm surfaces, such as the top of a television set. Warm temperatures cause flowers to wilt quickly. Keep floral arrangements out of cool or warm drafts, which speed transpiration and cause flowers to wilt quickly. With a few simple care techniques, floral arrangements may be enjoyed for an extended length of time.
Much can be done to extend the longevity of cut flowers and foliage. The methods of treatment after harvest are referred to as care and handling. For flowers to have lasting qualities, proper care and handling techniques are necessary at each level of distribution (often referred to as the chain of life). The grower, transporter, wholesaler, retailer, and final consumer each play an active part in determining the longevity and quality of cut flowers.
An understanding of the causes of premature aging in flowers gives insight and reason to the many procedures that help delay senescence. The stage of flowers at harvest, processing, water quality, chemical solutions, refrigeration, ethylene, and sanitation all are important considerations in the postharvest care of commercial and garden-grown flowers.
Terms to Increase Your Understanding
bud opening solution
care and handling
chain of life
fully open bud stage
half-open bud stage
silver thiosulfate (STS)
total dissolved solids (TDS)
Test Your Knowledge
1. Define the chain of life.
2. Describe basic care and handling procedures for cut flowers.
3. What are the primary ingredients in commercial floral preservatives? What is the function of each in increasing longevity?
4. When during the day should flowers be cut from the garden for use in fresh arrangements? Why?
1. Experiment with the longevity and vase life of various cut flowers. Process flowers differently and place stems in various water types, with and without commercial floral preservative. Record your results day by day.
2. Visit a wholesale or retail operation. Observe and learn how flowers are processed.
TABLE 10-1 FLOWERS AND FOLIAGE SENSITIVE TO DRYING AND WILTING Flowers * Anemone * Anthurium * Antirrhinum (snapdragon) * Astilbe * Bouvardia * Campanula * Celosia * Centaurea (cornflower) * Chrysanthemum frutescens (marguerite daisy) * Dahlia * Delphinium * Erica (heather) * Euphorbia (flowering spurge, poinsettia) * Freesia * Gerbera * Gypsophila * Iris * Orchids * Ranunculus * Rose * Saponaria * Scabiosa * Tulips Foliage * Adiantum (maiden hair) * Asparagus (ming fern, plumosa, sprengeri) * Caladium (angel's wings) * Calathea * Cordyline (ti leaf) * Nephrolepis (Boston and Oregon fern) TABLE 10-2 TROPICAL AND SUBTROPICAL FRESH-CUT FLOWERS SENSITIVE TO CHILLING INJURY * Alpinia (ginger) * Anthurium * Banksia * Camellia * Eucharis * Euphorbia (poinsettia and flowering spurge) * Godetia * Heliconia * Hippeastrum (amaryllis) * Leucadendron * Leucospermum * Orchids * Protea * Strelitzia (bird of paradise) * Tapeinochilus (wax ginger) * Telopea * Zingiber (shampoo ginger) TABLE 10-3 ETHYLENE-SENSITIVE FLOWERS * Aconitum (monkshood) * Agapanthus * Alstroemeria * Anemone * Antirrhinum (snapdragon) * Astilbe * Bouvardia * Campanula * Centaurea (cornflower) * Consolida (larkspur) * Dianthus (carnation, spray carnation, and sweet William) * Delphinium * Dendrobium * Eremurus (foxtail lily) * Freesia * Gypsophila (baby's breath) * Iris * Kniphofia (red hot poker) * Lathyrus (sweet pea) * Lilium (lily) * Matthiola (stock) * Narcissus * Ornithogalum * Phlox * Physostegia * Scabiosa (pincushion flower) * Solidago * Solidaster TABLE 10-4 TOP-RATED GARDEN FLOWERS (COLORFUL, LONG-LASTING, AND FAIRLY EASY TO GROW) * Achillea (yarrow) * Agapanthus * Anemone * Antirrhinum (snapdragon) * Aquilegia (columbine) * Aster * Astilbe * Calendula * Callistephus (China aster) * Celosia * Centaurea (cornflower) * Chrysanthemum * Consolida (larkspur) * Coreopsis * Cosmos * Dahlia * Delphinium * Dianthus (pinks, sweet William) * Digitalis (foxglove) * Gaillardia * Gladiolus * Gomphrena * Gypsophila (baby's breath) * Helianthus (sunflower) * Iris * Lilium (lily) * Limonium (statice) * Molucella (bells of Ireland) * Narcissus (daffodil) * Phlox * Paeonia (peony) * Ranunculus * Rosa (rose) * Rudbeckia (black-eyed Susan) * Scabiosa (pincushion flower) * Sedum * Tagetes (marigold) * Tulipa (tulip) * Zinnia TABLE 10-5 DECIDUOUS FLOWERING BRANCHES EASILY FORCED * Cercis canadensis (eastern redbud) * Chaenomeles speciosa (flowering quince) * Cornus florida (flowering dogwood) * Crataegus phaenopyrum (Washington hawthorn) * Daphne * Forsythia * Magnolia * Malus (apple and crabapple--edible and ornamental types) * Philadelphus (mock orange) * Prunus (almond, apricot, cherry, nectarine, peach, and plum--edible and ornamental types) * Pyrus (pear--edible and ornamental types) * Salix discolor (pussy willow) * Spiraea w* Wisteria
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|Title Annotation:||Section 2 Flowers and Foliage|
|Author:||Hunter, Norah T.|
|Publication:||The Art of Floral Design, 2nd ed.|
|Date:||Jan 1, 2000|
|Previous Article:||Chapter 9 Nomenclature and postharvest physiology.|
|Next Article:||Chapter 11 Flower and foliage forms.|