Post-Harvest Handling of Field Cut Flowers

Leonard Perry, UVM

Note: There are still flowers out there. This is a condensed article that was printed by the ARS with the author’s permission.

The keys to the longest vase-life (post-harvest longevity) of field-cut flowers are sufficient sugars/carbohydrates and sufficient water. These can be maximized through the maintenance of proper conditioning at all stages: pre-harvest, during harvest, and post-harvest. The goal in each case is to minimize stress and increase vase-life.

Pre-Harvest: The pre-harvest production factors that affect post-harvest life include planting in quality soil, adequate but not excessive fertilization and the best possible light. In addition the plants should be well watered throughout the growing period and turgid prior to cutting. It is ideal if the temperature is cool prior to harvest since the flowers will have more carbohydrates (sugars and other reserves) to help them last.

Time/Stage of Harvest: in general, the best times of the day for harvest are early in the morning or in the evening. The evening is best as the blooms will have the most sugars late in the day. It is also best if the temperature at the time of harvest is cool or cloudy since there will be less transpiration and attendant water loss.

Post-Harvest Factors: A number of factors affect the vase-life of cut flowers. These include light, the presence of which decreases sugars/carbohydrates.

They also include the amount of moisture. The higher the moisture at which the flowers are held, the longer will be the vase life. Moisture should be maintained at 60-80 percent relative humidity, which results in less transpiration and the attendant loss of water through the leaves.

The temperature at which flowers are held is very important, the cooler the better. Flowers should be held at a temperature of 40° F at which there is less water loss and depletion of sugars. It is critical, however, that the flowers not be frozen.

The quality of the water in which the blooms are held is also important. Water should be kept clean and replaced three-four days. Studies conducted on 16 species at the University of Vermont have shown there is no real difference between the use of tap vs. distilled water. The _PH of the water is, however, important. Acidic water, _PH 3.0-5.5, is best as it deters the growth of microorganisms which clog plant stems. In addition, flowers take up acidic water quicker.

The presence of ethylene gases is bad for many flowers, often causing them to age prematurely. It is therefore important to avoid storing cut flowers with fruits and vegetables that emit ethylene. Ethylene is also produced by damaged tissues and aging flowers, so it is best to keep old flowers away from freshly cut flowers and to ventilate the area of storage. The storage time of cut flowers should be minimized; the maximum period appears to be three-five days.

Stems of cut flowers tend to become blocked with bacteria and air bubbles. The use of clean containers and warm acid water after cutting helps to reduce air bubbles. The practice of re-cutting stems under water may not be needed based on tests of three species at the university. It may, however, be good insurance and can only help. It is also probably best to replace preservatives from time to time. In studies at the university this practice added two or more days to vase life.

Preservatives: The purpose of preservatives is to keep the water acid, provide sugars, and to counteract the effects of ethylene. Most home remedies like aspirin have been shown to have little or no effect. One effective home remedy is the use of 50:50 solution of lemon-lime soda and water. The soda is acidic and provides needed sugars.

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