Caring for Cut Flowers

Rod Jones

• Publisher: Landlinks Press
• Year: 2001
• Print ISBN: 9780643066311
• eBook ISBN: 9780643098732
• Edition: 2
• Topic: Biological Sciences
• Subtopic: Horticulture
• Index: Biological Sciences

Many florists and consumers still believe in old myths such as burning, bashing or boiling stems and adding aspirin to vase water. Scientific trials now show that such methods rarely help and some are actually damaging.

Caring for Cut Flowers shows florists and growers how to make cut flowers last longer. While proper postharvest techniques will not magically transform poor quality flowers into first class material, a few basic, inexpensive techniques can maximise the vase life of good quality material.

Rod Jones outlines in simple terms what to look for when buying and provides specific care instructions on what to do and what to avoid in handling, storing and displaying more than 100 common flowers, including Australian natives.

Chapter 1

THE FOUR BASICS OF FLOWER CARE

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There are four basic factors that affect the vase life of cut flowers:

1 the temperature at which the flowers are kept;

2 the quality of the water in which they are placed, and their ability to take up that water;

3 the food they are given; and

4 their sensitivity to ethylene.

A little scientific information is necessary to explain how each of these factors affects flowers.

1. TEMPERATURE

Temperature is arguably the most critical factor in the care of cut flowers. Cut flowers are living organisms, and have only a limited life. Nothing ‘goes off’ more quickly than a cut flower on a hot day. Most flowers are made up of thin, delicate petals that lose water and wilt rapidly; and the warmer the weather, the faster flowers wilt.

Flowers are genetically ‘programmed’ not to last. It takes a great deal of energy for a plant to produce large, brilliantly coloured flowers, and the plant would ‘prefer’ to do this only for a short time. For this reason, flowers are mostly short lived; they are designed to be pollinated by bees, insects or birds, set fruit or seeds, and then die.

Humans have changed this scenario to a certain extent by breeding plants that will produce large colourful flowers continually and for as long as possible. An interesting example of this is the Pansy, which in the wild is a perennial (flowers every year), but these days lasts only one season as it tends to flower itself to death.

The energy needed for plants to produce flowers is supplied by photosynthesis using sunlight, carbon dioxide and water to produce sugars (see below), and from the water and minerals the plant gets from the soil. The process known as respiration converts these foods (mainly sugars) into energy.

Respiration is used by all living organisms to produce energy through the chemical breakdown of sugars, carbohydrates and fats. In flowering plants, the energy produced by respiration is used to produce flowers in the first place, then open buds, create colours, nectar and pollen, and finally, wilting and flower death. The by-products of respiration are water, carbon dioxide and heat. Flowering plants have a relatively high rate of respiration, which results in the flowers themselves generating a substantial amount of heat. In other words, flowers naturally generate their own heat. And, in most cases, this heat will cause cut flowers to die faster if not controlled by refrigeration.

Respiration itself is controlled by temperature. Higher temperatures result in a high respiration rate, which in turn speeds up flower development, which means the flower will die more quickly. A helpful way to understand this is to think of the respiration rate as the rate of deterioration, or ageing of the flower. Therefore, the higher the temperature the flower is held at, the faster the respiration rate, and the sooner the flower will die. This is why we need to keep most flowers cool. Research has clearly shown that carnations held at 10°C, for example, will age and die eight times faster than a flower held at 1°C.

Cool temperatures, on the other hand, drastically slow down flower ageing by slowing respiration. Cool temperatures have the added benefits of dramatically reducing water loss and the effects of ethylene on cut flowers (see following sections). The end result of low temperatures, therefore, is longer flower life.

Keeping cut flowers at the coolest temperature that the flower will tolerate will maximise their life. Good growers, wholesalers and florists are always careful to keep cut flowers cool. After picking, growers place their flowers promptly in coolrooms, and transport them in refrigerated trucks. Wholesalers also keep their flowers in cool rooms and transport in refrigerated trucks.

It is important that this ‘cool chain’ is maintained by the florist. Every florist should have at least one display refrigerator. A small walk-in coolroom is very useful for keeping flowers not on display, or for finished arrangements prior to delivery.

Display your flowers in the coolest part of your shop—don’t display outside in hot weather. If outside displays are necessary, only use those flowers that tolerate high temperatures and at least make sure the flowers are kept in the shade.

When you sell flowers, advise purchasers on temperature management:

• take flowers home as quickly as possible: don’t leave flowers in hot cars;

• place flowers as soon as possible in a clean vase filled with cold water and treated with a preservative; and

• display flowers away from direct sunlight and other sources of heat, such as heaters and lamps.

TROPICAL FLOWERS

Not all flowers, however, need to be cooled. Tropical varieties (see below) are harmed by refrigeration. These flowers grow naturally in tropical regions where the air temperature does not fall below 18°C.

COOLING

It is vital, therefore, to know the appropriate storage temperature for each flower variety.

There are three important temperature ranges:

Full refrigeration (1°C to 4°C)

Most flowers last longest when kept between 1°C and 4°C. Many popular varieties are included in this group, namely Rose, Carnation, Chrysanthemum, all types of Lily, Iris, Tulip, Gypsophila and most types of foliage. Commercial coolrooms and high humidity refrigerators are commonly set around 4°C.

Moderate refrigeration (4°C to 6°C)

Some flowers need to be cooled, but they can be injured by temperatures below 4°C. Flowers in this class include Gladioli, Gerbera, Lisianthus, Alstroemeria, Stephanotis and Anemone.

No refrigeration (above 12°C)

Tropical flowers are damaged by cool temperatures. Flowers in this category include all Orchid varieties, Strelitzia (Bird of Paradise), Heliconia, Anthurium, Ginger, Gloriosa Lily, Poinsettia and Euphorbia. These varieties must never be refrigerated, and should be kept above 12°C at all times.

HUMIDITY

Most flowers should be kept in air with a high relative humidity (90 to 95%) to prevent them from drying out. Humidity refers to the amount of water in the air. Humid days are those when the air contains high levels of water (over about 80% relative humidity), while on hot, dry days the humidity level can fall to as low as 10%. In air-conditioned rooms and offices the air is quite dry, usually about 65% relative humidity. Flowers lose water much faster when the air is dry (low humidity), compared to when the air is damp.

Humidity control can really only be achieved when flowers are in coolers. The ideal humidity for flowers is between 90% to 95%, and it is not possible to maintain this humidity level in the shop, even with regular misting.

Some florists maintain a higher humidity in their display area by misting flowers. This is very helpful with some flowers, such as Hydrangeas, Boronia, Thryptomene and Violets, as they are able to absorb water through their petals and leaves. However, flowers such as Roses, Gerberas and Chrysanthemums are very susceptible to fungal diseases such as Botrytis, and misting increases the likelihood of fungal attack. If you are thinking of trying misting, check Chapter 5 (A to Z care guide) for each flower to see if it is recommended.

2. WATER

Water is essential for fresh cut flowers. Some cut flowers, such as Stirlingia, and some gum foliage are sold dried and dyed, and do not need water, but the vast majority of cut flowers are fresh and need a constant supply of clean water.

Cut flowers take up water from the vase through the cut stem end, wi...

Table of contents

• COVER
• TITLE
• COPYRIGHT
• CONTENTS
• ACKNOWLEDGEMENTS
• INTRODUCTION
• CHAPTER 1: THE FOUR BASICS OF FLOWER CARE
• CHAPTER 2: BUYING AND PREPARING FOR SALE
• CHAPTER 3: CUSTOMER SERVICE
• CHAPTER 4: FLOWER ARRANGEMENTS
• CHAPTER 5: A TO Z CARE GUIDE
• GLOSSARY
• REFERENCES
• INDEX