The group celebrated 20 years of looking after roses at the Dunedin Northern Cemetery, and 40 years of Heritage Roses New Zealand.
Eighty-two people took part in a series of events, including tours of the cemetery, garden tours, and a banquet dinner at Knox College on Saturday night.
Treasurer Ann Williams said after searching for a millennium project in 2000, the group worked with the Dunedin City Council on roses at the Dunedin Railway Station.
Following that, the group was contacted by the council, wanting to know the names of some of the roses at the cemetery.
When members visited the site, they found it in a state of disrepair.
"Grass was up to our knees," Mrs Williams said.
The group decided to take the cemetery on as a project and started planting roses.
"We decided that we would use this as a conservation area for very rare roses."
More than 1000 roses are now planted at the cemetery.
Tragedy struck in 2016 when about 500 roses were accidentally poisoned by the spraying of a herbicide.
After a lot of hard work, the group has returned the site to its former glory.
The group has a working bee on the first Monday of every month, as well as a four bigger working bees each year.
"We do that on a regular basis.
"Rain, hail or snow, we’ve had it all."
