KEEPING CUT FLOWERS

While everybody enjoys fresh cut flowers around their house, few people know how to keep them for as long as possible. This may be done by keeping in mind a few simple facts.

An important thing to remember about cut flowers is that they are sensitive to temperature. For example, studies have shown that cut car­nations retain their freshness eight times longer when kept at 12°C than when kept at 26°C. Keeping freshly harvested flowers at the right temperatures is probably the most important aspect of flower care.

Flowers are not intended by nature to live very long. Their biological purpose is simply to attract birds or insects, such as bees, for pollination. After that, they quickly wither and die. The pro­cess by which flowers consume oxygen and emit carbon dioxide, called respiration, generates the energy the flower needs to give the flower its shape and colour. The making of seeds also depends on this energy. While all living things respire, flowers have a high level of respiration. A result of all this respiration is heat, and for flowers, the level of heat relative to the mass of the flower is very high. Respiration also brings about the eventual death of the flower, thus the greater the level of respiration, the sooner the flower dies.

How, then, to control the rate at which flowers die? By controlling respiration, how is respir­ation controlled? By controlling temperature, we know that respiration produces heat, but the reverse is also true. Thus by maintaining low temperatures, respiration is minimised and the cut flower will age more slowly (Tropical flowers are an exception to this rule; they prefer warmer temperatures).

Cooler temperatures also have the benefit of pre­serving the water content of the flower, which helps to slow down ageing as well. This brings us to another important aspect of cut flower care: humidity. The average air-conditioned room has a relative humidity of 65 per cent, which contri­butes to greater water loss in the flower. Flowers are less likely to dry out if humidity levels are 90-95 per cent, but this may be unrealistic unless you live in the tropics or subtropics.

Yet another vita! Factor in keeping cut flowers is the quality of the water in which they are placed. Flowers find it difficult to 'drink' water that is dirty or otherwise contaminated. Even when water looks and smells clean, it almost certainly con­tains bacteria and fungi that can endanger the flowers. To rid the water of these unwanted germs, household chlorine bleach can be used in small quantities. It is recommended that 15 drops of chlorine bleach (at 4 per cent solution) be added to each litre of water. The water and solution should also be replaced each day.

When buying cut flowers, look for ones that have not been kept (by the flower shop) in direct sun­light or strong wind. If the flowers are not freshly harvested, ask whether they have been stored in a refrigerated cool room.