As the process advances, staff at the garden are keeping a close eye on the plant (Amorphophallus titanium), known for producing the world's largest flower with a nauseating smell, comparable to rotting flesh.
The plant's blooming process was ''well advanced'', but staff were unsure when the flower would actually bloom.
''It keeps its own timetable,'' garden team leader Alan Matchett said yesterday.
The covering sheath had fallen away exposing the ''frilly part'' of the bloom, and the central spadix which, he said was ''growing rapidly''.
It was uncertain when the bloom or inflorescence would actually open.
But when it did, it would be the first for the plant which arrived at the garden in 2008 as a small corm donated by a private collector.
And it would be the most southerly flowering of the plant in the world.
Its flower would last for only one to two days and many visitors were expected to view it in the winter garden hothouse.
