Six species and cultivars of 2 genera from Australia, 2 cultivars of one species from New Zealand and 13 species and cultivars of one genus from South Africa were evaluated for potential use as cut greens in commercial floriculture in June and December in water and commercial preservative solution for periods of 30 days. The stems were not recut, but the holding solutions were changed 2 times per week. The Australian “smoke bush,” Adenanthos sericeus, produced 30 days vase life, regardless of treatment or time of year. For most species, foliage produced during the cool, short day season had the longest vase life. Nine species and cultivars lasted 4 weeks or longer, regardless of treatment from the December trials, while only Adenanthos produced that result in June.
A Tropical Surge
Cut greens are used in floral designs, wreaths and dried arrangements. The U.S. value of all sales at wholesale for cut cultivated greens in 1990 was $111 million (USDA, 1990). By 2007, this had decreased to $92.5 million, of which 42% was leatherleaf fern (Rumohra adiantiformis).Only 15 states were represented in the most recent survey with Florida (79%) and Oregon (5%) contributing the greatest amounts attributable to specific states (USDA, 2008). Besides leatherleaf fern, Chamaedorea palm, huckleberry (Vaccinium sp.), salal, Pittosporum tobira, and assorted conifers as Christmas greens represent other major cut greens, but a tremendous variety of foliages is being used. The surge in interest in tropical cut flowers, such as gingers and heliconias generated an interest in exotic foliages to accompany them. Cordyline fruticosa (syn. C. terminalis), green ti, is the only cut foliage Hawaii exports in reportable quantity. However, many other foliages are included in mixed flower shipments sent directly to customers in the continental U.S. The value for green ti and other cut foliages exported from Hawaii in 2008 was about $1,800,000.
The objective of a project at the Maui Agricultural Research Center, Kula, Hawaii, was the evaluation of southern hemisphere flora for floral and landscape value, Although the Proteaceae have been a primary focus for new cut flowers, the family also includes some interesting candidates for commercial cut foliages in the genera Grevillea and Leucadendron.
Plants, grown from cuttings collected in Australia, New Zealand and South Africa, were established in 1985 at the Maui Agricultural Research Center. Twenty mature, firm stems of 21 plant materials, approximately 40 cm long, were harvested in December, 1990, and June, 1991. Four varieties, whose growth was too soft for the June trials, were not evaluated and show no vase life for June (Table 1).
Vase life of the plant material was determined by placing 10 stems each in two holding solutions: water and a commercial floral preservative, Floralife, at a concentra-tion of 9 g per liter. The solutions were replaced two times per week, and the stems were not recut. Air temperature in the laboratory during the vase life trials ranged from a maximum of 20C in January and 22.5C in June to minimums of 13.5C in January and 13.4C in June. Light was provided eight hours daily from two banks of 40-W fluorescent fixtures 1.8 m above the containers.
For a period of 30 days, observations were made and the number of stems judged to be “acceptable” were recorded. Criteria used to determine when a stem was to be discarded included wilting, desiccation, loss of color, or loss of 50% of the leaves on a stem. Days of vase life were determined by totaling the daily number of “acceptable” stems during the 30 day test period and dividing by the number of stems at the start.
The vase lives of 21 potential cut foliages, in water and preservatives, in December and June are presented in Table 1. In December, all 21 varieties had a minimum of 14 days vase life in water or preservatives. In June, 15 varieties had at least 14 days vase life in water or preservative.
In December, nine varieties lasted 28 days or more in water or preservatives while in June, only one, Adenanthos sericeus, lasted 28 days in either water or preservatives. It is likely that cooler temperatures and short days had hardened the foliages harvested in December.
In general, Leucadendron and Grevillea benefited from the use of floral preservatives. These two genera also shed fewer leaves during the trials, while the Coprosma selections shed their leaves continuously. The Coprosma selections lasted longer in water than in preservative solution.
Ranking the plant material by averaging the vase life in both solutions and times of year, Adenanthos sericeus is highest with an average vase life of 29.5 days, followed by Leucadendron X ‘Pisa’ at 27.5 days and Leucadendron X ‘Safari Sunset’ and Leucadendron salignum ‘Yellow Bird’ at 27 days. The longest lasting Grevillea was G. diminuta (26.8 days). Coprosma repens produced an average vase life of 26.8 days.
Although Broschat and Donselman showed vase life values in excess of 120 days for several species, a practical vase life of 30 days was chosen in these evaluations. Few cut flowers will outlast the foliages we evaluated. Some of the Leucadendron selections are colorful enough when the male or female inflorescence is produced to merit design value of their own for this feature. Several Grevillea selections have attractive inflorescences, but would be chosen for foliage use because of silvery under-surfaces, feathery texture, and long-lasting qualities.
Originally published in Acta Horticulturae 337:95-98 (1993) by the International Society for Horticultural Science, Leuven, Belgium. Reprinted with permission of ISHS.