Grevilleas as Cut Flowers - Part One
The woody plant genus Grevillea contains some of the showiest members of the Australian flora and are among the most popular natives for garden cultivation in this Australia. In addition to the species, hybridisation and selection has produced many cultivars in a wide variety of floral colours and forms which are appreciated by both humans and birdlife. Furthermore, the range of growth habits from trees and shrubs to prostrate groundcovers mean they can be utilised in many ways in the landscape.
While a familiar sight in local gardens, grevilleas aren't generally thought of as flowers for cutting. This is in spite of the fact that many of their cousins in the family Proteaceae Banksia and Telopea (better known as Waratah) and the African genera Protea, Serruria, Leucadendron and Leucospermum are well established in the commercial trade [1,2]. Nevertheless, in recent years there has been increasing interest in Grevillea by the industry at home and abroad.
Before discussing use of the actual flowers, the value of grevillea foliage in floral arrangements must be acknowledged. Many Grevillea species have interesting leaves which are variously shaped and coloured and some of the early interest by florists actually lay with the foliage rather than the flowers. An American floriculture manual published in 1922 refers to using seedlings of Grevillea robusta (Silky Oak) to fill out window boxes as a substitute for Boston fern .
More recently Grevillea baileyana has gained attention for its lobed juvenile leaves with bronze undersides and their long vase life .
While individual flowers (florets) all display the distinctive Proteaceae morphology , the number and presentation in the inflorescence varies considerably. For floristry, varieties with large cylindrical/conical brush-type blooms borne at the ends of branches have received the most attention. Most have parentage including Grevillea banksii or related species  derived from subtropical and tropical parts of the continent.
Short vase life has been a major impediment to the use of grevilleas as cut flowers in the past, with premature abscission of the florets from the stalk being a common complaint. Wilting and colour loss can also be a problem. Work is being done, however, to improve the ability of the flowers to withstand transport and handling and give the final recipient a satisfactory display.
One of the most important discoveries has been determining the best stage at which to harvest. The point at which styles fully emerge from the flowers is too late. The blooms should be picked while the styles are still looped within the perianth. This may be between 10% to 100% of styles on the inflorescence looped, with the optimum depending on the cultivar [7,8].
Other lines of research include treatment with sugars, hormones or other chemicals after harvest or in the vase water. Such techniques are used with many other floral crops. It is also important to know factors such as ethylene sensitivity and optimal temperature and humidity .
Furthermore, some varieties have been shown to perform better than others, which suggests hybridisation and selection could produce even better varieties. Some work in this direction has been done [6,10].
Next time in part 2 - Using grevilleas from your garden
References and other sources
 Tropical grevilleas vase life better than expected. Australian Horticulture, Sept 1996 p43-45
For more background information about grevilleas in general see the list of links on www.calyx.com.au/native_species/grevillea.html