Postharvest Handling Tips for Some Spring Flowering Bulbs
Most people associate spring with the vibrant colors and diverse shapes offered by the wide varieties of spring-flowering bulbs. According to the International Flower Bulb Centre in Holland, the number of bulbs exported from the Netherlands has steadily increased every year due to the successful promotional programs run by the Centre as well as the growing interest of the general public for colorful flowers in early spring. A significant portion of the bulbs are forced in the greenhouse for cut flower production. Americans purchased more than 83 million cut tulips each year. Of that, 24 million stems were grown in the US and the remaining 59 millions stems were shipped from Holland (Netherlands Flower Bulb Information Center in Brooklyn, NY).
The postharvest life of many early spring bulb cut flowers is relatively short when compared to other species of cut flowers frequently used in the floral industry. However, with some simple postharvest treatments, one can extend the postharvest quality and life of the flowers and, consequently, satisfy more customers. In this article, the postharvest tips for cut tulips, daffodils, and hyacinths are discussed.
Cut tulips are one of the most popular of the spring bulbs. The short postharvest life of this flower, however, requires very careful handling at all steps in the marketing chain:
- Harvest the flowers when the entire bud is colored but still closed. If tulip buds are harvested at an earlier stage than recommended, flowers will not fully develop in the consumer home. Harvesting the buds too late, on the other hand, reduces the vase life of the flowers. Keep the crop dry to reduce the occurrence of Botrytis that often attacks cut tulips.
- Place the flowers in a 33o-35o F cooler as soon as possible with a relative humidity of more than 90%. This process causes the petals to quickly close up, thereby reducing the mechanical bruising of petals that occurs during bunching. In addition, storage at this temperature reduces the consumption of the limited amount of stored carbohydrates as well as reduces water loss from the flowers.
- Bunch the flowers by lining up the buds to the same height. Trim ½ to 1 inch off the end of the stems. Place the flowers upright in clean, cold (32o -35o F) water for at least 30 minutes. It is critical that the stems are kept upright during this time (especially of those that have been left dry for some time) as tulip stems will assume whatever shape the stems are in during the rehydration process. Make sure that the buckets are clean by washing them with a dilute bleach solution before use.
- Store the flowers in an upright position for, preferably, no more than 2 days. If flowers are to be stored for more than 2 days, extra handling steps should be taken to assure good postharvest quality. Steps include leaving the bulb attached to the flowers when harvested (this will allow the continued transport of the stored carbohydrates from the bulbs to the flowers), wrapping the bunched flowers tightly before storage, and storing the flowers dry (not in water) and in a horizontal position. Make sure that the temperature in the cooler is around 33o F and the relative humidity is high in order to prevent desiccation of the petals. With this method, the flowers can be stored for several days in a cooler. Before selling the flowers, cut off the ends but leave the wrapping on the bunch. Bunches should remain in an upright position and tightly wrap during rehydration (6 to 8 inches of 100o F lukewarm water) to prevent stems from becoming wavy.
Cut narcissus, like tulips, have a very short vase life. The vase life of different cultivars, however, can vary significantly. Therefore, choosing cultivars with a long vase life is an important step in assuring quality cut narcissus. In addition, careful handling can further increase the postharvest life:
- Harvest the flowers when the buds have opened (the papery spathe has already split and the tips of the petals are showing). Flowers harvested at an earlier stage may not open. Harvest the leaves along with the flowers.
- Store the flowers in an upright position in a 32o - 35o F cooler with a relative humidity of more than 90%. Rapid cooling of the flowers is essential for a good product. Make sure that the stems remain upright to avoid bending. Flowers can be stored up to 1 week.
- Before selling the flowers, trim 1/4 to 1/2 inch off the stems and then place them in 6 to 8 inches of warm water (100o F). Allow the flowers to harden for at least 2 hours. A word of caution is that you must never place other fresh cut flowers, especially tulips, in the same bucket as narcissus during the first 24 hours. Experiments have demonstrated that the sap from cut narcissus is 'toxic' to tulips and significantly reduces the vase life of the flowers. After the 24-hr period, cut narcissus can be used in a bouquet without negatively affecting the postharvest quality of the other flowers.
When used as cut flowers, harvest when the bottom 1-2 flowers on the inflorescence begin to open.
- Leave the bulb's basal plate intact to improve the postharvest quality of the flowers as well as to increase the length of the product.
- If flowers are to be stored, make sure that they remain in an upright position and are placed in a 32o to 35o F cooler. During shipping, wrap flowers with plastic sleeves to prevent the florets from drying.
- Never recut the stems before selling (the standard practice in handling most cut flowers) as cut hyacinths require the basal plate for continuous absorption of water.
The Internet contains a great deal of useful information on growing bulbs for sale as potted plants and as cut flowers. The web sites at the end of this article contain technical information and marketing ideas for commercial growers, as well as information that may be of interest to the general public.
- Bulb Flower Production - Service Bulletin, 1999. Cut Flowers. No. 5. International Flower Bulb Centre.
- Holland Bulb Forcer's Guide. 1996. DeHertogh, A. A. (ed.). 5th edition. pp. 530. Alkemade Printing.
- The Physiology of Flower Bulbs. 1993. DeHertogh, A.A. and M. LeNard (eds). pp. 811. Elsevier Science Publisher.
Dr. Susan S. Han, Stockbridge School of Agriculture
University of Massachusetts, Amherst
Links to Further Resources on the Web
- The International Flower Bulb Center provides excellent information on the commercial forcing of a variety of bulbs, both as cut flowers and pot plants.
- The Geophyte Page by Dr. William B. Miller at Cornell University is another source of information on bulbs, corms, tubers, and other geophytic plants and is primarily oriented towards commercial growers, forcers, and retailers.
- This ATTRA publication on Sustainable Cut Flower Production is a good general introduction to the topic, though it does not deal specifically with cut flowers from bulbs.
- The USDA's Market News Service provides a listing of current Flower prices at the Boston Terminal, updated weekly.
- The Web Page of the Association of Specialty Cut Flower Growers. Mostly consists of lists of members, events, and recommended books.
- Kansas State University's Construction of Cold Storage for Specialty Cut Flowers and Plant Material, Harvest Systems for cut flowers and Commercial Production of Gladiolus are publications that require acrobat reader.