Refrigeration is a highly effective method for the short-term preservation of fresh flowers, acting as a temporary pause button on their natural aging process. By controlling the environment, you can significantly extend the period cut flowers remain vibrant. This technique is often used by florists to maintain inventory quality. Applying this method at home maximizes the vase life of a bouquet, especially if storing them for a day or two before an event.
The Science of Cold Storage
The beneficial effect of cold storage on flowers stems from its ability to manipulate the flowers’ internal biological processes. When a flower is cut, it continues to use its stored energy reserves through respiration, which consumes sugars and leads to decline. Lowering the ambient temperature significantly slows this metabolic rate, conserving the flower’s limited sugar supply.
For most cut flowers, a temperature range between 34 and 37 degrees Fahrenheit (1 to 3 degrees Celsius) is ideal for slowing down respiration. Cold temperatures also minimize the rate of transpiration, which is the loss of water vapor from the flower’s surface. Reducing this water loss helps prevent wilting and keeps the petals and stems firm and hydrated.
Preparing Flowers for Refrigerator Storage
Proper preparation is necessary to maximize the benefits of cold storage and prevent damage. Before placing flowers into the refrigerator, remove any foliage that would sit below the waterline, as this decaying material promotes bacterial growth. Use sharp shears to re-cut the stems at a 45-degree angle, which increases the surface area for water uptake.
It is helpful to place the newly cut stems in lukewarm water for about 30 minutes for a quick hydration boost before cooling. Once hydrated, the flowers should be secured to protect their delicate structure. Loosely wrap the entire bunch in a protective layer, such as newspaper or a plastic bag, which helps maintain high humidity. This wrapping prevents the dry air of the refrigerator from causing dehydration.
Essential Precautions for Domestic Refrigeration
Using a standard home refrigerator requires awareness of several potential hazards that can quickly ruin flowers.
Ethylene Gas
The most significant danger is ethylene gas, an odorless plant hormone released by ripening fruits and vegetables, such as apples and tomatoes. Ethylene is a powerful aging accelerator that can cause premature wilting, petal drop, and color loss in sensitive flowers. To avoid this, you must clear the refrigerator of all produce that emits ethylene before introducing the flowers.
Temperature Control
Temperature control is important to prevent cold-induced damage. While the ideal temperature is just above freezing, ensure the flowers are not placed directly near the cooling vents or the back wall of the refrigerator. Temperatures in these areas can drop low enough to cause freezing injury.
Moisture Management
Managing moisture is a balancing act; while humidity is needed, excessive condensation can lead to fungal diseases like Botrytis. The protective wrapping helps, but flowers should not be overly misted before storage. Ensure the refrigerator compartment is clean to minimize the risk of mold or bacterial contamination. Storing flowers for short periods, such as overnight, is generally the safest approach in a domestic setting.