Directors at the Eden Project are trying to work out how to raise a further £27m to finance their plans for a large expansion programme.
A new education centre is planned
Two weeks ago the Millennium Commission gave Eden £10m towards the cost of an education centre and a new desert biome.
But it was only about a third of what they had actually asked for.
However, Eden did very well to get £10m from the Commission as it was far more than they gave any other attractions this time around.
The planned features will cost almost as much as the original development.
Eden directors say they are confident of finding other sources for the cash. However, they cannot yet say what those sources might be.
Malcolm Bell, of South West Tourism, said it was up to the government to come up with the cash.
He said: "Eden is an international success. It is a real national asset.
"The credibility of the country is at stake. The government should invest in this wonderful success."