Recommendations for Maintaining Postharvest Quality
Produce Facts in English > Gladiolus
Michael S. Reid
Department of Plant Sciences, University of California, Davis
Gladiolus cvs. hybrids. Still an important commercial cut flower despite a substantial decline in production in recent years, gladiolus responds well to proper postharvest management. The smaller-flowered and ‘butterfly’ cultivars, as well as modern standards in a variety of colors and forms have helped transform this often stereotypic funeral flower into a contemporary favorite that can be an important accent flower in arrangements. Gladiolus is Latin for small sword, in reference to the sword-shaped leaves. Modern day gladioli are the results of hybridization programs, using South African species, that commenced in Belgium around 1841.
Normal harvest is at the stage when the bottom two or three florets on the spike are showing color. For long-distance transportation, an even earlier harvest stage can be recommended if it is combined with sugar pulsing to ensure proper opening of the flowers at their destination. Local market flowers are cut when the first floret is open. Harvesting is carried out so as to leave as many leaves on the plant as possible. A knife is run down between the leaves with the back of the knife down. When the knife blade is as low as the cutter believes it should go, it is pulled upward and out, severing the stem, which can then be pulled out of the leaves. It is possible to open almost all florets on flower spikes if they are harvested in the green bud stage and handled properly. However, it is recommended that color should be visible in one to three florets at time of purchase to help ensure that most florets will open.
Grading and Bunching
Gladioli, like most spike-type flowers, are very sensitive to the force of gravity, and will always tend to grow away from the ground, particularly at warm temperatures. This can result in permanent deformation of the upper part of the spike, and consequent reduction of flower quality. Throughout the postharvest procedures, gladioli should be held upright to avoid this effect. This rule may be relaxed only while the flowers are held at low temperature during storage and transportation. Quality factors for gladiolus include stem straightness and strength, freedom from damage and disease, and maturity. The flowers are bunched by color and maturity in groups of 10.
Although exposure to ethylene does not affect the life of open florets, it can reduce the flower life by causing abortion of unopened buds (Serek et al., 1995).
Gladioli respond very well to pulsing with a preservative containing 20% sugar (sucrose or glucose). Pulse overnight at room temperature or in the cooler. The flowers can be pulsed in the dark. Treatment with 1-MCP or STS provides some protection against the effects of exposure to ethylene (which causes young buds to abort).
Although earlier recommendations were to store gladiolus at 5ºC to prevent chill damage to tips, our research has shown that they can safely be stored for a week at 0-1ºC. The flowers are negatively geotropic (they bend away from the force of gravity), so they are commonly stored and shipped upright. One beneficial aspect of low temperature handling and transportation is that this negative geotropic response is inhibited, allowing gladioli to be packed in the standard horizontal flower box. For longer storage, gladioli are best stored upright at the lowest safe storage temperature.
Traditionally packed in tall 'glad hampers' clearly marked for upright stacking. Since the advent of pre-cooling, some shippers have packed gladiolus in normal flower boxes. This practice is fairly safe if the flowers will remain refrigerated throughout the marketing chain, and will be removed from the box on arrival. Excessive moisture on the foliage should be avoided so as to minimize the risk of Botrytis infection.
Some cultivars are sensitive to fluoride which can result in deterioration of the petal margin (bleaching, water soaking, and then necrosis), failure of florets to open and develop normally, burning of the floret sheath, and marginal leaf scorch.
First published on this website: October 2004