For cut flowers, storing them in a refrigerator extends their freshness and ornamental life. The lower temperature environment slows the biological processes that cause the flower to wilt and decay. Professional florists use this technique, known as cold-chain management, to maintain inventory quality before arrangements are delivered. Understanding this preservation method allows anyone to maximize the longevity of a bouquet at home.
How Cold Temperatures Slow Flower Deterioration
The primary mechanism by which refrigeration preserves flowers is by slowing the plant’s metabolism. Cut flowers continue to respire, consuming stored sugars to produce energy after being separated from the root system. This energy is necessary for the flower’s cells to maintain turgidity and structure.
Storing flowers at a lower temperature reduces the rate of respiration, conserving the limited carbohydrate reserves within the stem and petals. Cooler temperatures also minimize transpiration, the natural process of water loss through the leaves and petals. This reduction helps the flower maintain hydration, preventing wilting and drooping.
For most non-tropical cut flowers, the optimal storage temperature is between 33°F and 38°F (1°C to 3°C). This chill inhibits metabolic activity without causing freeze damage to the delicate plant tissues. Maintaining this consistent, low temperature is the foundation for prolonging the flower’s vase life.
Step-by-Step Guide for Refrigerating Cut Flowers
Proper preparation is necessary before placing cut flowers into a refrigerated environment. Begin by giving the stems a fresh cut at an angle using a sharp knife or shears, which maximizes the surface area for water absorption. Any foliage that would sit below the water line should be removed to prevent bacterial growth and stem clogging.
The flowers should then be placed in a vase filled with clean, lukewarm water for initial hydration before cooling. If a floral preservative packet is available, this should be mixed into the water to provide a carbohydrate source and inhibit microbial development. Ensure the flowers are fully hydrated, or pre-chilled, before they enter the cold storage environment.
For storage, the refrigerator temperature should be set to 40°F or below, but it must remain safely above the freezing point of 32°F. Flowers can be stored upright in their vase or loosely wrapped in damp newspaper or plastic sheeting to create a moist microclimate and prevent physical damage. A common practice is to place the flowers in the refrigerator overnight, or for six to eight hours, before removing them to display during the day, which extends their longevity.
Environmental Hazards That Negate Refrigeration
While the cold temperature is beneficial, certain factors within a typical household refrigerator can accelerate flower deterioration. The most significant hazard is ethylene gas, a naturally occurring, odorless plant hormone released by ripening fruits and vegetables. Even a small amount of ethylene acts as an aging signal for flowers, causing premature wilting, petal drop, and fading.
Items such as apples, bananas, pears, and tomatoes are high producers of ethylene and must be removed from the refrigerator before storing flowers. Failure to clear the refrigerator of these items negates the positive effect of the cold temperature and can shorten the flower’s life span.
Accidental freezing is another risk, as temperatures falling below 32°F (0°C) will cause the water inside the flower’s cells to freeze and expand. This expansion ruptures the cell walls, leading to irreversible damage that appears as translucent, wilted, or mushy spots on the petals and leaves. Furthermore, while high humidity is desirable to prevent drying, excessive moisture that causes water droplets to form on the petals can create an environment conducive to the growth of mold and fungi, such as Botrytis.