Botanic Gardens Trust, Sydney, Australia

Control of flowering in Waratahs

Dr Cathy Offord - Manager Horticultural Research

The waratah is well known as the NSW floral emblem but is also a very striking cut flower. Commercially grown waratahs flower in spring within a 5-6 week window, producing bright red terminal flowers. Several cultivars of T. speciosissima and hybrids of T. speciosissima, T. mongaensis and T. oreades have been selected to provide an array of forms in whites, pinks and reds. Despite increasing domestic and export market demand, the waratah industry has failed to fulfil its potential in terms of producing large quantities of premium quality blooms that command high returns. A major impediment has been the inability to predict and manipulate flowering time to avoid oversupply in spring and to extend the season to supply major marketing events such as Christmas. Understanding the mechanisms that control flowering will enable growers to select suitable cultivars and time the marketing of blooms to maximise profitability.

Extending the commercial waratah flowering season has long been a major goal for researchers at the Royal Botanic Garden, Sydney, and the University of Sydney. A new research collaboration between the NSW Wildflower Industry, the Royal Botanic Garden, Sydney, Rural Industries Research and Development Corporation and the University of Sydney (led by A/Prof Robyn McConchie) will examine the contribution of temperature, day length, age, size and nutritional status of stems to flower induction, initiation and development in selected waratah cultivars. Based on that information, it will be possible to investigate the influence of growth regulators and canopy management in manipulating timing of anthesis. An understanding of the phenology of flowering will also assist in understanding the impact and mitigation of climate change on natural and commercial stands of waratah.

Flowering-in-Waratah-cv-Olympic-Flame
Cv Olympic flame. Photo: Jaime Plaza

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