A giant flower that smells of rotting flesh has bloomed for the first time ever in New Zealand.

The strange and unpredictable titan arum - also known as the "corpse flower'' - began unfurling in the tropical glasshouse at the Auckland Domain Wintergarden about 2pm yesterday and was now in full bloom today.

Auckland Council said the flower was expected to remain in bloom for the rest of the day, and public visiting hours had been extended to 8.30pm for today only.

The fully unfurled flower was now showing its deep burgundy interior. It was giving off only a light smelly odour this morning, but its signature rotting flesh smell may intensify as the day progresses and the temperature in the glasshouse rises.

The rare Amorphophallus titanum originates from the rainforests of Sumatra in Indonesia, and has been growing at the council-owned nursery and Wintergarden for about seven years.

Auckland Domain manager David Millward said it was the first time the plant had produced a bloom, creating a good deal of excitement amongst his team and visitors to the garden.

"The titan arum, as it's commonly known, can produce a single leaf the size of a small tree every year for seven to 10 years before showing any signs of producing a flower," he said.

"We have been watching this one very closely and were delighted to finally confirm that a flower was on the way - it felt a bit like being expectant parents."

Mr Millward said he hoped many visitors were able to come and see the titan arum, as it may well be a once-in-a-lifetime opportunity.

"If it gets very busy, we may need to carefully manage entry to ensure everyone gets a chance to move through the glasshouse and we'll be reminding people that it's very warm and smelly inside."

Auckland Council parks, sports and recreation manager Ian Maxwell said it was a momentous occasion for the Wintergarden at for botany in New Zealand.

He said many New Zealanders would have seen the plant on David Attenborough's Kingdom of Plants documentary but never thought they might see one in Auckland.

"We are very proud to be joining places like the Royal Botanic Gardens of Kew and Melbourne in producing one of these flowers.''

The bulb of the titan arum produces a single leaf the size of a tree each year.

Read more: Corpse flower a Kiwi first

For seven to 10 years it goes through a life-cycle of leaf, dieback and dormancy before a bloom may appear. Once the flower starts to emerge it can grow to more than 3m tall, at a rate of 10cm per day.

Both male and female flowers are produced in the same inflorescence - the female flowers open first, and the male a day or two later.

The flower is in the Wintergarden's tropical glasshouse, which maintains an average temperature of 28C.

- APNZ