Keeping flowers in the refrigerator overnight is a common practice florists use to maintain their quality. Refrigeration acts as a temporary preservation method, slowing the natural processes that cause flowers to age and wilt. Storing flowers in a properly prepared, cool environment for a short period, such as six to twelve hours, helps significantly extend their vibrant appearance.
The Science of Cold Storage
Cold storage manipulates the flower’s internal biological functions. A cut flower consumes its limited energy reserves through respiration, a form of slow “breathing.” Lowering the temperature dramatically slows this metabolic rate, conserving the stored sugars that fuel the cells. Research indicates that for every 10-degree Fahrenheit drop, the flower’s metabolic rate can be reduced by half, delaying the onset of aging (senescence).
Cooler temperatures also address water loss, the primary cause of wilting. At room temperature, flowers lose water rapidly through transpiration (evaporation of moisture from petals and leaves). The reduced temperature in the refrigerator slows this evaporation, helping the flower maintain its turgidity and crispness. By slowing both energy consumption and the rate of water loss, refrigeration grants the flower a temporary reprieve from decay.
Preparing Flowers for the Fridge
Successful overnight refrigeration depends on proper preparation to ensure the flowers remain hydrated and protected. Begin by giving the flowers a fresh, angled cut on their stems using sharp shears to maximize the surface area for water absorption. Immediately place the trimmed stems into cool, fresh water, allowing them to fully hydrate for at least 30 minutes before moving them to the refrigerator.
Next, remove any foliage from the stems that would sit below the water line when placed in a vase. Submerged leaves quickly decompose, causing a rapid buildup of bacteria that clogs the stems and prevents water uptake. For delicate blooms or arrangements that cannot be placed in a vase, wrap the flower heads loosely in damp newspaper or paper towels. This creates a small, humid microclimate that prevents the petals from drying out.
When placing the flowers inside the refrigerator, ensure they stand upright to prevent the stems from bending and maintain their natural shape. Position the flowers in a secure spot where they will not be crushed by other items. This careful preparation ensures the cold temperature slows the aging process without causing physical damage.
Hazards: Ethylene and Freezing
While cold storage is beneficial, the average home refrigerator presents two significant hazards. The first is ethylene gas, a natural, odorless plant hormone released by ripening fruits and vegetables (especially apples, bananas, pears, and avocados). This gas dramatically accelerates flower senescence, causing symptoms like petal drop, premature wilting, and yellowing of the leaves.
Because a refrigerator is a small, enclosed space, a single piece of ripe fruit can create a concentrated ethylene environment highly damaging to sensitive flowers like carnations, lilies, and roses. Therefore, remove all fruit and vegetables from the compartment where the flowers will be stored. The second hazard is freezing damage, which occurs when temperatures drop below 32 degrees Fahrenheit.
Water inside the plant cells freezes at this temperature, forming ice crystals that rupture the cell walls and cause irreversible tissue damage. Home refrigerators often have cold spots near freezer vents or the back wall where temperatures fluctuate. To avoid this, place flowers in the warmest area, such as the door or a middle shelf, and aim for a temperature range between 34 and 37 degrees Fahrenheit for optimal, safe storage.