Follow Postharvest Instructions Carefully

The green dragon of envy crawled up my leg as I watched John Dole give his postharvest presentation at the Lilytopia Growers’ Symposium at Longwood in May. His easy style and smooth delivery contrasted sharply with how I feel when I give presentations. Sometimes the flow is smooth. Other times I feel more like a teenage trying to master the combination of clutch release while shifting gears. It’s unnerving to see confusion flash across faces in the audience. Am I squeezing in too many topics? Mea culpa! It is difficult to discuss differences and similarities of treatments without referencing other variables involved, such as temperature, sanitation, cutting stage, etc., all which affect vase performance.

Postharvest recommendations are not stand-alone decisions. I work as the tech consultant for Chrysal USA and in that capacity, I mention specific Chrysal products because I know the line and have data to back my claims. I cannot speak as comfortably about competitors’ solutions.
Please use my recommendations as a springboard, rather than an endorsement, and test different brands. Comparison testing is the best way to determine what product works gives the best results under your conditions.

Take dosage information, for example. Slow-release chlorine pills work great for zinnias, but the pills are one product for which the dosage is a moving target. For gerberas, the dose is strong, 1 pill per 2 quarts (½ gallon water). For all other flowers, 1 pill treats 4 to 6 quarts water, reducing the chlorine strength considerably. Recently, a grower contacted me saying her flowers looked terrible although she was using the product recommended for zinnias. Zinnias are very susceptible to bacterial pollution, which causes the fibrous tissues to “disappear” and stems to collapse—it’s almost like the bacteria “eats” the xylem tissues. Working with the philosophy, “If a little is good, more is better,” she was treating each bucket with two pills, and the high level of chlorine was causing stem browning and foliage burn. Simply reducing the dose solved the problem.

Growers Chime In

No solution will make a bad flower better or give it supernatural power to perform beyond its inherent genetic potential. The (vase life) clock starts ticking with cultivar selection. Post-harvest solutions simply maximize the vase performance so blooms reach full potential.

North Carolina member Gary Calder recently addressed this very point in an ASCFG Bulletin Board posting: “When SOMEONE (ahem) forgets to properly hydrate BEFORE cutting a group of plants, the result doesn’t always show itself in the cutting or processing stage or even necessarily in the delivery part, but (only) after they have been delivered and used do the flowers wilt down. When you don’t properly hydrate a flower before cutting it (keeping in mind that a stem is basically a straw that has been cut, and that it has cell walls that MUST be turgid), the problem won’t manifest itself like some other problems might. It’s our responsibility to manage all aspects of the culture of our plant material.”

Sometimes cut stage determines the best solution to use. For example, if sunflowers are cut before the petals emerge—maybe rain is forecasted or the sales window needs to be extended to maximize prices—and the cut point is super tight, a low-sugar flower food is needed to ensure petals emerge and flowers color up fully. Conversely, if sunflowers are cut when open, treating them in a hydration solution or slow-release chlorine (neither contain sugar) are better options.

During the Portland Conference in 2008, our guide at Swan Island Dahlias recommended boiling water for dahlia postharvest. Such an old-fashioned method of treating was surprising since there are better and easier options that give perfect results. I conducted a series of tests over three months at a large grower on California’s central coast a few years back, comparing Chrysal and Floralife hydration solutions on different colors of ‘Karma’ series. Consistently, the best results were achieved with Chrysal Professional gerbera pills or Chrysal Professional #1 as first drink overnight and then Professional #2. The flowers were given 4 days simulated wet-pack transport at 34F and Chrysal Professional #2 was compared with Floralife Professional in the second phase of the tests. Other summer beauties like callas, centaurea and celosia respond to the solution sequence that gave good results for the Karmas. Hydration gets the flow going, flower food keeps colors vibrant and controls stem splitting in callas.

High temperatures during summer harvest make it super important to rebalance water relations fast. One hydration solution choice to get flow into carthamus, asters, matricaria, sinuata statice, solidaster, gentiana and cotinus, regardless of harvest temperature is Chrysal OVB (note: Floralife does not offer a comparable product.) Like any hydration formula, OVB is all about getting flow going and keeping the solution clean. It gives a neutral pH and contains no sugar which means after 3 days, it’s important to transfer flowers into flower food so buds have the carbo-boost needed to open. Frank Arnosky, Texas Specialty Cut Flowers, swears OVB allows him to harvest when temperatures soar over 100F.

Swishing Isn’t Enough

Another part of the vase life matrix involves sanitation. Recently, a distribution center flower quality control inspector told me about tests he made comparing gerbera vase life of various cultivars. He made 4 replications using tap water as the solution. In two sets of vases, he dipped his cutters into cleaner solution prior to cutting every time he transferred flowers to the next phase of the test. Using a second set of cutters, he purposely did not dip to see how clean tools affected the vase life. Regardless of the cultivar, the flowers cut with disinfected cutters stood 1.5 up to 3 days longer than those cut with non-disinfected shears. Sanitation makes a difference at every step.

It is important to respect the difference between cleaning and disinfecting. A water swish doesn’t do either. Cleaning is removing organic material, grease and lime deposits. Disinfecting is killing bacteria and fungi. To clean and disinfect, add a small amount of bleach to your detergent-based cleaner solution or scrub with a cleaner and dip buckets in a bleach solution.

Polly Hutchison recently shared the way she prevents cross-contamination during harvest: she places a bucket containing disinfectant solution and clippers at the end of the row so the harvesting team can easily exchange used tools for clean ones as they finish a row.

Bacteria block flow of water and nutrients. Remind customers to avoid consolidating used solutions when consolidating displays—a very common procedure in both retail and wholesale. The clarifiers in flower solutions are quickly overwhelmed when blooms are placed in dirty buckets or when old solutions are poured together. Recommend they always store blooms in some kind of solution to control bacteria and top-up with fresh solution, not water or ice.

Happy summer!

Gay Smith

Technical Consulting Manager

Gay Smith is the Technical Consulting Manager for Chrysal USA. Contact her at [email protected]