1) Drying
Since flowers and foliage consists of more water, dehydration is necessary for getting dry flowers. Methods used for removing water from plant parts are Air-drying, Sun drying, Oven drying, Embedding (sand, borax, silica gel and combination of these materials), Glycerining (Glycerinating), Microwave oven drying, Freeze-drying and Press drying. i. Air drying Tie the flowers in loose bunches and hang upside down until they are dry in a room with good ventilation and darkness. It is the ideal method for seedpods, grasses and many flowers having more cellulose material. Crisp textured flowers like Helipterum, Helichrysum and Limonium could easily be dried either by hanging or positioning them erect in containers for 1-2 weeks. Gomphrena flowers from half to full bloom maturity take 7-9 days for air drying and roses take 5-10 days. Acacia, amaranths, castor flowers, citrus leaves, cockscomb, corn flower, fennel, fern, golden rod, gypsophila, grasses, herbs, ear heads of wheat, oat and rye, hydrangea, lavender, protea, marigold, poppy seed pods, physalis, peppers, roses, statice, thistle, yarrow and yucca can be dried by this method. ii. Sun drying Plant material is embedded in drying medium (sand) in a container and exposed to the sun daily to facilitate rapid dehydration. In India, open sun drying is followed for drying many flowers. Flowers like small zinnias, marigolds, pansies, and pompon chrysanthemum embedded in sand upside down fashion and kept in the Sun would dry in a day or two. For Gomphrena, Zinnia and French marigold it would take 3-4 days. Open sun drying is followed for corn flowers, custard apple (small), Casuarina pods, mini coconut, eucalyptus, evergreen cones, gomphrena, gourds, pomegranates, poppy pods, lotus pods, typha heads, palm leaves, grass ear heads. iii. Oven drying Electrically operated hot air oven at a controlled temperature of 40-50 oC is used for drying flowers in an embedded condition. Chrysanthemum, dombeya, gerbera, and limonium take 48 hours at 45-490C, French marigold takes 72 hours, African marigold takes 96 hours and Nymphaea takes 120 hours for drying. China aster, delphinium, rose buds and small flowers, and zinnia take 48 hours at 40 - 44 0C, medium and large roses take 72 hours and very large flowers take 96 hours in 40 - 44 oC. iv. Embedding method Embedding the flowers in a granular, desiccating material is probably the most commonly used method and many consider it the best all around method. Several materials may be used, and they vary in cost and the results that they produce. To cover a flower, put about an inch of desiccating material at the bottom of the container; cut the flower stem to about a half an inch and stick this into the center of the material at the bottom to hold the flower. Next, pour the desiccating material along the perimeter of the container, away from the flower, building up a continuous mound of about an inch. Then tap lightly on the container and the material will move to the flower, not altering the form of the petals. Continue adding the material, tapping on the container, etc. until the flower is completely covered. Lastly, add an inch of the material above the top of the flower. Sand, borax, silica gel, saw dust, perlite and combination of these materials are used in this method. Sand and Borax methods though relatively cheap, take longer time and labour for drying. Silica gel is the ideal drying agent for delicate flowers such as roses, carnation, dahlia etc. It takes less time and can be reused indefinitely after removal of moisture from the silica gel crystals by drying them in an oven at 250 0F for 1 hour. French marigold and zinnia (half to full bloom stage) take 4 days for drying by silica gel embedding. Wiring of flowers before drying is essential for which 20-24 gauge florist wire is used. Chrysanthemum takes 5 days for drying in silica gel. Ageratum, anemone, amaryllis, bleeding heart, baby’s breath, bachelors button, chrysanthemum, calendula, clematis, crocus, daffodil, dahlia, daisy, delphinium, gloriosa lily, gaillardia, geranium, gladiolus, hyacinth, hibiscus, lily, marigold, pansy, petunia, poinsettia, poppy, rose, salvia, snap dragon, stock, tulip, verbena and zinnia are the flowers suitable for embedding method of drying. v. Microwave oven drying Electronically produced microwaves liberate moisture from organic substances by agitating the water molecule. It is fast and the results are good. The flowers has to be embedded in silica gel medium in a microwave safe open container along with a small cup with water nearby. Standing time of 10 minutes to few hours is needed after the drying for best results. vi. Glycerin drying (glycerinization) ‘Glycerinizing’ is the term used in the ornamental cut flowers and foliage industry to describe the treatment of fresh plant materials with a hygroscopic (water attracting) chemical with the objective of retaining the suppleness of the plant materials. Foliage treated with glycerin keeps almost indefinitely and remains pliable. Glycerin preserves foliage by replacing the natural moisture present in the leaf with a substance that maintains the leaf form, texture and sometimes the colour. Fresh and fairly matured foliage is ideal for glycerining. About 50 per cent of most plant fresh weight is water, but brittleness is usually only a problem if the water content falls below 10 per cent. vii. Freeze drying Freeze dried flowers are fresh flowers that have been specially dried to preserve their natural shape, colour and beauty. Freeze drying is accomplished by a process called sublimation. It requires a special freeze-drying machine. It involves first freezing the flowers at (-) 10 C for at least 12 hours. A vacuum pump slowly pulls the water out of the flowers as a vapor in one chamber, and then the vapor condenses as ice in another chamber. Because of this process, the shape and natural color of the flower is maintained. For Roses it takes 15 – 17 days and for other flowers normally 10 – 12 days. Major flowers dried by this method are roses, carnation, bridal bouquets etc. Flowers recommended for freeze drying viii. Press drying Flowers and foliage are placed in-between two folds of newspaper sheets or blotting paper and these sheets are kept one over other and corrugated boards of the same size are placed in-between the folded sheets so as to allow the water vapour to escape. The whole bundle is then placed in the plant press, its screws tightened. After 24 hours the bundle is removed to an electric hot air oven for 24 hours at 40-45oC. The following flowers and foliage are dried by this method. Flowers: Candytuft, Chrysanthemum, Euphorbia, Lantana, Larkspur, Mussaenda, Pansy, Pentas, Rose and Verbena. Foliage: Thuja, Taxodium, Marigold, Grevillea, Rose, Ferns, Casuarina, Silver oak and Grasses.  |
Last modified: Thursday, 10 May 2012, 4:49 AM