The plant, named Amorphophallus titanum, only blooms once every few years and has caused a stink when it has opened up in the past, most notably at the Wintergarden in Auckland in June 2015.
Christchurch City Council Botanic Gardens director Wolfgang Bopp said the corpse flower smells like a piece of rotten meat when it's fully opened.
He said it normally takes seven to 12 years for the plant to come to flowering size and the flower only lasts about 48 hours.
He said people are waiting to see the blossom as it might be a once in a lifetime experience.
"It's something that so rarely happens.
"As far as we know, it's the first one that's flowering with us at the [Christchurch] Botanic Gardens and people want to be part of it, which is exciting," he said.
Another corpse flower has started to open at the Wintergarden in the Auckland Domain.
