Temperature management is the most effective method for significantly extending the lifespan of cut flowers. Placing blooms in a chilled environment is a technique borrowed directly from professional florists who rely on specialized coolers to maintain product freshness. This cold storage mimics the natural dormancy of flowers, effectively pausing the aging process from the moment the stem is cut. Controlling the temperature dramatically increases the period of time flowers remain vibrant.
Ideal Preservation Temperature Range
The optimal temperature range for storing most non-tropical cut flowers is narrow, falling between 33°F and 35°F (0.5°C to 2°C). This specific chill slows metabolic activity without causing chilling injury or freezing plant tissues. Temperatures below 32°F (0°C) are dangerous because ice crystals can form within the cells, leading to irreversible damage and wilting.
A standard home refrigerator is typically set between 37°F and 40°F, which is slightly too warm for maximum preservation. The temperature inside a home unit can fluctuate, with areas near the back often running colder and risking accidental freezing. Monitoring the refrigerator temperature with a separate thermometer is advisable to ensure the flowers remain within the ideal zone.
Why Cold Temperatures Slow Deterioration
The goal of cold storage is to reduce the flower’s respiration rate, the process of converting stored sugars into energy. Once cut, a flower relies on finite carbohydrate reserves since it cannot produce food through photosynthesis. Lowering the temperature slows this energy consumption dramatically, conserving the flower’s food source for a longer duration.
This reduced metabolic rate also limits transpiration, which is the loss of water vapor from the petals and leaves. High temperatures accelerate water loss, leading to dehydration and wilting. Keeping the temperature low allows the plant to retain moisture more effectively, preserving the crispness of the blooms. Additionally, cold temperatures inhibit the growth of microorganisms, such as bacteria and fungi, that can clog the stem’s vascular system and hasten decay.
Preparing Flowers for Refrigerated Storage
Successful refrigeration depends heavily on preparation steps taken before the flowers enter the cold environment.
Stem Preparation and Hydration
The first step involves re-cutting the stems at a sharp angle using a clean, sharp blade. Cutting the stem while submerged underwater prevents air bubbles from blocking water uptake and causing dehydration.
Before refrigeration, remove any foliage that would sit below the waterline. Submerged leaves decompose rapidly, contaminating the water with bacteria that travel up the stem. After trimming, allow the flowers to fully hydrate in fresh water for at least 30 minutes before moving them to the chilled space.
Managing Humidity
When storing flowers dry, the blooms should be loosely wrapped in damp newspaper or a plastic film to create a high-humidity microenvironment. Cut flowers require 90% to 95% atmospheric humidity to prevent desiccation, a level rarely found in a standard home refrigerator. For storage in water, covering the vase or bucket with a loose plastic bag helps trap moisture and maintain the necessary humidity.
The Danger of Storing Flowers Near Produce
A risk of storing flowers in a home refrigerator comes from the presence of fresh fruits and vegetables. Many types of produce, particularly ripening items, naturally release ethylene, a colorless and odorless gas. This gas is a plant hormone that regulates ripening and senescence.
Exposure to even low concentrations of ethylene can cause flowers to age prematurely, resulting in wilted petals, dropped buds, and a shortened vase life. Common high-ethylene producers include:
- Apples
- Bananas
- Pears
- Melons
- Tomatoes
Florists use specialized coolers designed to filter out this gas, but a home refrigerator lacks this capability. To protect blooms, remove all ripening produce from the refrigerator before placing the flowers inside. Although a cold environment reduces a flower’s sensitivity to ethylene, the high concentration of the gas in an enclosed space still poses a significant threat.