Garden information centre volunteer Lynne Jackson made the half-metre-long cake replica of the Edwardian glasshouse for the celebration, which was attended by about 60 people.
The winter garden was the first public conservatory in Australasia and was built as an attraction for the colder months.
Curator Stephen Bishop said it provided an environment to grow plants from all over the world that could not otherwise grow in the Dunedin climate.
There are 1500 plants in the conservatory, including tropicals, subtropicals, cacti and succulents.
The winter garden was donated to the city by Robert Glendining, who established Ross and Glendining, operators of the Roslyn Mill, with John Ross.
It is a popular attraction.
There were 15,000 visitors in the first three months following the opening on October 3, 1908.
In June 1909, it was reported that 1408 people visited the garden in about two hours.
Now, there are 200 visitors each day, although yesterday the garden had between 400 and 500, Mr Bishop said.
"I would expect it to be here in another 100 years."
Staff at the Botanic Garden said the garden and building is an integral and educational part of the garden.
"You can see plants like coffee and sugar, basic food items that come from the tropics," Mr Bishop said.
The old coal-fired boiler used to heat three sections to tropical temperatures was replaced with an electric heater in 1962 in a "modernisation" of the building and a fernery was attached.
In 1991, the building was restored to the original design and the fernery was removed.
There will be tours of the conservatory during the weekend and early in the coming week.
- Mary Holmes
