The newspaper is a month older, as the garden opened on June 30, 1863, in an area facing Albany St, now part of the University of Otago.
In 1868, flooding destroyed much of the garden, including one of the two memorial oaks planted when the garden was opened.
The other, now a mature specimen tree, was moved in 1870 when the garden moved to its present site.
"The Friends of the Dunedin Botanic Garden wish to acknowledge the establishment date with a birthday party on Saturday, July 1, from 11am to 2pm," Friends president Sam Moncur said.
There will be free train rides on the Crest train, balloons, paper leaves on which to record favourite parts of the garden and birthday cake, decorated by Di Hanson of Di for Cakes.
"The cake will be an eight-inch, three-layer chocolate gateau, appropriate as July 1 is World Chocolate Day," Mr Moncur said.
Friends secretary Sue Lambie said local florist Lily Boyce was doing a special floral arrangement, to be displayed in the information centre, using material from the Winter Garden.
Women from Images of the Past, dressed in Victorian and Edwardian costumes, will add to the atmosphere.
A park bench, below the information centre ramp, will be dedicated to the volunteers who have been involved with the garden over the years.
"This is to be the start of of a series of events running for 12 months," Mrs Lambie said.
A main thrust of the celebrations will be the Otepoti Dunedin Heritage Festival in October, which this year has as the theme "Growing Heritage".
The Dunedin Botanic Garden is working on events to be held at this time, culminating with the annual Rhododendron Day plant sale on October 15.
