The director of the once-threatened National Botanic Garden of Wales says it still needs public funding, despite increasing visitor numbers.
The garden's iconic glass house was designed by Sir Norman Foster
Kevin Lamb wants to develop the garden as an educational and scientific institution with the extra money.
Three years ago, the £43m attraction in Carmarthenshire was within hours of having to call in administrators.
It was saved by a package of public funding, but this money will come to an end in 2009.
The Welsh Assembly Government, Carmarthenshire Council and the Millennium Commission pledged to put £1.5m into the garden as part of a five-year recovery strategy when it was in danger of closure in 2004.
A new plan to take the garden on when this money comes to an end in 2009 has been implemented by Mr Lamb, who is hoping to see a 20,000 increase in visitor numbers between now and then.
However, increased takings alone will not be enough to fund science and education projects, Mr Lamb told BBC Radio's Eye on Wales.
"We have a successful business strategy that is delivering revenue into the garden so the amount we need is far less as a proportion than botanic gardens elsewhere," he said.
"But if the garden is here for education and science, those things cost and don't necessarily generate the sorts of revenue needed to sustain."
In 2006, 120,000 visitors went through the turnstiles of the gardens at Llanarthe.
These figures are forecast to increase further with the opening later this year of a tropical house designed by acclaimed Welsh architect John Belle.
Plans by a pharmaceutical company to create more than 40 jobs when it moves to the purpose-built science centre in a few months have has also bolstered confidence at the gardens.
A glasshouse designed by John Belle will open later this year
It is this success that has led Carmarthenshire Council chief executive Mark James to believe that the issue of financial support should be re-visited by politicians.
"I think there's far more realism around the table and a belief that we can work together and continue to work together to develop the gardens," he told Eye On Wales.
Mr Lamb's plans also have backing from the scientific world.
Professor Denis Murphy, head of biotechnology at the University of Glamorgan, said public money spent bolstering the garden's science could help scientists study the effects of climate change in Wales.
"it might be that we'll be looking at different kinds of plants growing in Wales in the next 10 years," he said.
"The garden really could contribute an awful lot to that. That's real good public work."
Eye on Wales is on BBC Radio Wales at 1830 BST on Monday, 7 May.