Out of sight, out of mind By Dr. Claudio Pasian OSU, Columbus, OH Is that your approach to post production quality? Do you know how long and how well your plants last? Remember that a satisfied customer will probably buy again in the future. While most growers are very familiar with the importance of the post-harvest qualities of cut flowers, some do not realize that the post-production of characteristics of container (pot) plants are of equal importance. For example, some container-sold plants such as African violets, geraniums, impatients, and primulas are very sensitive to ethylene, just like some cut flowers. Do you know the post-production characteristics of the crops you grow? Are you using all the tools that are available to you so that you produce a long lasting plant? You can increase the post-production quality of your crops by following a few cultural practices that add little or no extra cost: 1) Decrease growing temperatures towards the end of the crop. Lowering air temperature by 2ºF will intensify color and increase plant longevity. 2) Avoid extreme temperatures during shipment. Symptoms of extreme temperature damage vary according to species and can appear several days after plants are out of the boxes on destination. 3) Manage fertilization programs during production. Mums and poinsettias benefit if fertilizers with a high ammonium to nitrate ratio are replaced by a fertilizer high in nitrate nitrogen. High ammonium levels during growth result in leaf yellowing and reduced mum post-production life. Poinsettias and azaleas last longer if fertilization is reduced a couple of weeks before shipping. 4) Select cultivars that have a natural tendency to last longer. 5) Treat ethylene sensitive plants with ethylene blockers. Some chemicals have the ability of blocking both internal and external ethylene. Some commercial examples of these chemicals are STS and MCP. STS (Silver thiosulphate) is no longer used because of environmental considerations: silver is a heavy metal very toxic to different forms of life. MCP (1-methylcyclopropene) on the other hand, has the same effect of STS without the environmental problems. MCP is a gas that has to be applied by locating plants in a chamber (some growers treat plants in the transporting truck). Cost estimates run between 1 - 2 cents per pot. Plants that are highly sensitive to ethylene: Achimene, African violet, begonias, caladiums, carnations, geraniums, impatiens, kalanchoes, marigolds, Easter lily, orchids, petunias, primula, salvia, snapdragons, sunflowers. Plants that are sensitive to ethylene: Ageratum, alstroemeria, azalea, bouganvillea, calceolaria, celosia, cineraria, coleus, cyclamen, dahlia, fucshia, hibiscus, ivies, oriental and asiatic lilies, poinsettia, pothos, roses, streptocarpus, vinca.