He said: "With these sound guides, there's a tendency to tell you too much and to go on too much.
"Often, some of these gallery guides go on and on and on. And you see people on autocue going around like zombies.
"It's good if the person can have their own discovery."
Sir Roy made his outspoken criticism at the Cheltenham Literature Festival, where he was speaking about The Laskett Garden.
The garden, in Herefordshire, is the largest private formal garden to be created in England since 1945 and was a 30-year labour of love for Sir Roy and his late wife Julia Trevelyan Oman.
He was quick to point out that visitors to the Laskett receive only scant information about each section.
But recalling one mosaic exhibition he saw recently, he joked that he urged one visitor to stop listening to the guide, saying: "Look at the mosaic, woman, not her!"
He also remembered becoming exasperated when observing another museum visitors' group looking at an iPad version of Rembrandt's 1642 painting The Night Watch when they were stood in front of the real thing.
He said: "They'd rather watch the Night Watch on TV than see the real picture."
Sir Roy, whose wife Julia died in 2003 from pancreatic cancer, lives in the village of Much Birch, which lies 8 miles south of Hereford.
It was here that the pair created their garden, which is full of references to their romance of three decades.
He said that after her death, he tried to clear out some of her plant collections, including her 130 varieties of crab apple trees.
His head gardener ended up planting them around Hereford at bus stops and other random locations, which, he said, "she would have liked."
He added: "[The garden] has been edited down from what it was. It was much more confused before."
On his gardening philosophy, he said: "I never mind breaking the rules. It accounts for a lot of my success. Never take any notice of whatever anyone else says."
- The Daily Mail
