The goal of storing cut flowers is to significantly extend their vase life by slowing down the natural aging process. Temperature control is the most influential factor in achieving this preservation, as it governs the speed at which the flower consumes its internal resources. Maintaining an appropriate, consistent storage temperature minimizes stress, keeping blooms dormant and fresh until display.
The Role of Temperature in Flower Physiology
Low temperatures dramatically reduce the flower’s metabolic rate. This slowdown primarily affects respiration, the process where the flower consumes stored sugars (carbohydrates) to produce energy and heat. Slowing respiration preserves the limited energy reserves within the cut stem, delaying natural decline and wilting (senescence).
A cool environment also controls the rate of transpiration, which is water loss through the petals and leaves. Since a cut flower cannot efficiently replace lost water, minimizing moisture loss is necessary to maintain turgidity. Keeping the temperature low reduces water loss to the surrounding air, preventing dehydration and bent necks.
General Temperature Guidelines for Storage
The optimal temperature range for storing the majority of temperate cut flowers, such as roses, carnations, and lilies, is extremely precise. This range is maintained between 33°F and 35°F (about 0.5°C to 1.5°C). This narrow window drastically reduces metabolic processes while remaining slightly above the freezing point of water.
Staying above freezing prevents the formation of ice crystals, which would rupture cell membranes and destroy tissue. If the temperature rises even a few degrees above 35°F, respiration accelerates, rapidly depleting energy stores and shortening vase life.
Addressing Cold Sensitivity and Temperature Exceptions
Not all flowers benefit from temperatures near freezing, as many species are susceptible to chilling injury. This damage occurs when cold-sensitive flowers, primarily those from tropical or subtropical climates, are stored at temperatures too low for their physiology. Chilling injury can cause symptoms like water-soaked spots, tissue browning, or failure to open properly.
For these warm-weather exceptions, including tropical varieties like orchids, bird of paradise, and anthuriums, the ideal storage temperature is significantly higher. These flowers require a range between 50°F and 55°F (about 10°C to 13°C) to prevent cellular damage. Storing cold-sensitive blooms alongside temperate flowers in a 33°F cooler will cause them to deteriorate quickly.
Avoiding Environmental Factors That Accelerate Deterioration
While temperature is the primary control, other environmental factors can quickly undermine chilled storage. Ethylene gas, a naturally occurring plant hormone, acts as a powerful aging accelerator that speeds up senescence and causes premature petal drop and wilting. This colorless gas is emitted by ripening fruits, decaying plant matter, and combustion sources like vehicle exhaust.
Flowers must never be stored near a fruit bowl or in a refrigerator used for produce, as the blooms will absorb the ethylene gas. Furthermore, flowers should be kept away from drafts, direct sunlight, and heat sources. Rapid temperature fluctuations or exposure to high heat causes a sudden increase in transpiration, leading to immediate and irreversible dehydration.