The Royal National Rose Society, based at the world-renowned Gardens of the Rose near St Albans, has gone into administration.
Formed in 1876, it is the world's oldest specialist plant society.
It is responsible for classifying new types of roses, and runs trials for both amateur and professional breeders.
In a statement the organisation said administrators had been appointed and would be in contact with members, stakeholders and creditors.
The society, which has members across the world, said its aim was to create a "living dictionary" of roses in its gardens at Chiswell Green.
The site is normally open to the public for several weeks in the summer months and was due to reopen for 2017 on 10 June. It is now uncertain whether that will happen.
Former employees told the BBC they were not surprised the society had gone into administration after years of it struggling financially.
The site is adjacent to the former Butterfly World sanctuary which closed in 2015 because it failed to attract enough visitors to make a profit.