The owners of Lissadell House in Co Sligo, where the gardens opened to the public yesterday, have declined to avail of a €1.1 million State grant announced earlier this year.
The grant was announced last March under Fáilte Ireland's tourism product development scheme but co-owner Edward Walsh said that there were so many conditions attached that it was "rendered impractical".
At the time Minister for Tourism John O'Donoghue said the gardens would be a significant visitor attraction and an important tourism asset.
"If we had availed of the grant we would not be in a position to open the gardens today," said senior counsel Mr Walsh, who bought the estate with his wife, barrister Constance Cassidy, in December 2003.
The mayor of Sligo, Cllr Tom MacSharry, officially opened the newly restored walled kitchen gardens and seashore alpine gardens at the ancestral home of Countess Markievicz.
Hundreds of alpine and herbaceous plants which had been choked by ivy and brambles for 100 years were unveiled to the public.
In the early 1900s Sir Jocelyn Gore-Booth, a brother of the countess, ran a major horticultural enterprise at Lissadell, where he employed more than 200 people.
The family ran a sawmill, oyster farm and school of needlework, and Sir Jocelyn was famous for his bulb farm, where more than 250 varieties of daffodils were produced, many of which he created.
There are now 37 varieties of daffodils in Lissadell "but we have over 200 to go", Mr Walsh said. He estimated that the cost of reclaiming the entire garden and glasshouses would be more than €2 million.
"Many of the original plants were literally uncovered by hand where they had been choked by ivy and brambles," he explained.
Last year more than 20,000 people visited Lissadell House but the owners say that the target for the gardens is up to 100,000 annually.