Postharvest of Specialty Cut Flowers – NC State Report for 2004
F.L. Fanelli, J.M. Dole, W.C. Fonteno, B.T. Harden and S.M. Blankenship, Department of Horticultural Science, North Carolina State University, Raleigh, NC 27695-7609
This project was supported by the American Floral Endowment, the Association of Specialty Cut Flower Growers, and numerous suppliers. The authors would like to thank Ingram McCall, Diane Mays, Aliya Donnell, and Leslie Tichner for growing the cut flowers and for assisting with the postharvest studies.
Working with new cut flowers is fun. We get to see and enjoy the latest species available. During the summer our coolers are filled with an ever changing display of colors and species. It is a great business to be in. This year was no different as we had many new cultivars to work with and a number of them had long postharvest lives. The NSCU postharvest research process consists of two stages. Stage I. Each year an initial postharvest screening is conducted on the most promising species/cultivars from the seed, perennial, and woody trials. This year we screened 21 new cut flower species/cultivars. Those with the longest vase life included Adenophora ‘Amethyst’, Ammi ‘Casablanca’, Campanula ‘Heavenly Blue’, Dianthus ‘Sweet Coral’ and ‘Sweet Red’, Eustoma ‘Twinkle Blue Blush’ and ‘Twinkle Pink’, Matricaria ‘Magic Lime Green’, Helleborus hybrids, Persicaria ‘Silver Dragon’ and Zinnia ‘Oklahoma Carmine’ and ‘Yellow’. Stage II. In this stage four cultivars were produced in large quantities and subjected to extensive postharvest testing examining ethylene sensitivity, anti-ethylene agents, optimum cold storage duration, pretreatments and pulses, vase solutions and substrates, and commercial preservatives. This year we studied Lupinus ‘Sunrise’, Trachelium ‘Jemmy Royal Purple’, Zinnia ‘Benary’s Scarlet Giant’, and Zinnia ‘Sungold’.
Field grown flowers were harvested at the optimum stage of development into buckets of tap water. The stems were processed, sorted and placed in the following treatments:
- Hydrator only
- Holding preservative only
- Hydrator followed by holding preservative
- Distilled water only
Chrysal Professional RVB Hydrating Solution (hydrator) was used at the 0.2% rate and Chrysal Professional #2 Processing Solution (holding) was used at the 1% rate. After treatment, stems were placed at 68±4°F under approximately 200 ftc light for 12 hrs/day.
Our testing methods tend to produce the maximum vase life, which tells you the potential vase life of each species. We cut and process the stems rapidly, put one stem per jar, and use a postharvest temperature that is cooler than a typical home in the summer time. These procedures were set up to provide a consistent environment so that anyone else should be able to repeat our work and get the same results. All of these factors typically add about 1 to 3 days to the vase life of some species compared to that of a typical cut flower producer. For example, flowers with a vase life of 6 to 8 days in testing would probably last 5 to 7 days for a typical grower and flowers lasting 16 to 18 days would probably last 13 to 15 days.
For several cultivars, we also listed the minimum vase life. We harvest and test 40 to 60 stems per cultivar and present the average vase life. With some cultivars most of the stems died about the same time. However, with other cultivars the flowers were terminated over a long period – thus the vase life of some of the stems was much shorter than the average. In those cases, we have included a minimum vase life.
We also use distilled water, which most people are not using. However, in most of our studies we found no difference between distilled water and our regular tap water (0.21 EC, 6.1 pH). So if you have good quality water then your results should be similar to ours.
Adenophora ‘Amethyst’ This species had long stems of pendulous blue bell-shaped flowers with a vase life of 11 days, which was increased by up to 3 days using a holding solution. The minimum vase life was 6 days.
Agapanthus ‘ MidKnight Blue’™ This bulbous perennial had a 10 to 11 day vase life in high quality water. Commercial preservatives had no effect. The minimum vase life was 7 days.
Ammi ‘Casablanca’ These cultivar has lacy white flower heads tinged with green. Commercial preservatives had no effect on the 15 day vase life. The minimum vase life was 13 days.
Campanula rapunculus ‘Heavenly Blue’ The stems of this new annual were covered with many delicate light blue bell-shaped flowers. A vase life of 11 to 15 days was obtained without the use of commercial solutions.
Campanula takesimana ‘Kent Belle’ Using a hydrator only or hydrator plus holding preservative extended the vase life of this traditional deep blue perennial bell flower by 3 to 4 days over the control of 12 days. Florets did not drop as the stems mature.
Caryopteris ‘First Choice’ This small shrub produced whorls of blue flowers, which lasted 14 to 15 days. Floral preservatives had no additional effect. The minimum vase life was 5 days.
Dianthus ‘Sweet Coral’ and ‘Sweet Red This sweet William flowers rapidly from seed in the first year and was best treated with only the holding preservative for a 20 day vase life, although holding in water only produced a respectable 15 day vase life. Combining the hydrator with the holding preservative caused leaf browning.
Digitalis ‘Camelot Lavender’ and ‘Camelot Rose’ This new series of foxglove flowers in the first year from seed. Placing the stems in holding preservative added 1 day to those held in water that had a vase life of 8 to 9 days. The minimum vase life was 7 days.
Eustoma ‘Twinkle ‘Blue Blush’ The use of a holding preservative increased the vase life 2 days beyond the 17 days of the stems held in water only. The minimum vase life was 13 days.
Eustoma ‘Twinkle Pink’ The use of a holding preservative increased the vase life 3 days beyond the 14 days of the stems held in water only. The minimum vase life was 8 days.
Lobelia ‘Fan Blue’ The stems of deep blue florets with lustrous green foliage lasted 12 days with an increase of only 1 day when placed in holding preservative. The minimum vase life was 7 days.
Matricaria ‘Magic Lime Green’ The use of holding preservative increased the vase life 4 days over the control of 20 days. The minimum vase life was 11 days.
Helianthus ‘ProCut Orange’ This pollen-free sunflower had 3 to 4 inch wide flowers, which lasted up to 10 days in water. The minimum vase life in the water only treatment was 8 days. Using a holding preservative extended the vase life by one day. However, using both hydrator and holding solutions decreased average vase life to 5 days, with a minimum vase life of 4 days.
Helianthus ‘ProCut Bicolor’ This sunflower has a mahogany ring around the dark center disc. Flowers lasted 9 to 10 days regardless of treatment. The minimum vase life was 7 days.
Heliopsis helianthoides ‘Summer Sun’ This bright yellow perennial continued to flower throughout the summer. Vase life averaged 10 to 11 days in all treatments, except that the treatment combining hydrating and holding solutions reduced average vase life to 7 days, with a minimum vase life of 2 days. The minimum vase life for the other treatments was 6 days.
Helleborus hybrids Combining the hydration and holding preservatives resulted in a 17 day vase life compared with a 10 day life for the water only treatment. The attractive seed pods continued to develop prolonging the vase life. The minimum vase life was 4 days for the water only treatment and 7 days for the other treatments. See separate article for more information.
Persicaria ‘Silver Dragon’ Grown for its burgundy, green, and silver foliage, this species had an exceptionally long vase life of 3 weeks or more. Stems also had a tendency to root. Needless to say, the rooted stems lasted a very long time. Think of the marketing possibilities – its not just a bouquet, its a future garden.
Zinnia ‘Oklahoma Carmine’ All treatments resulted in a long vase life with no detrimental effects for this bright rose colored zinnia. The stems in water only lasted 19 days while the longest vase life was 20 days for stems pretreated with the hydrator and placed in water. The minimum vase life was 8 days, however.
Zinnia ‘Oklahoma Yellow’ The yellow ‘Oklahoma’ zinnia had an even longer vase life than ‘Oklahoma Carmine’ for all treatments. The longest vase life was 24 days using only the hydrator while the stems in water lasted 22 days. The minimum vase life was 8 days, however.