Prince Charles Eavesdrops on Tourists, Speaks to Plants Royal leader comes clean about "eccentric" behavior in new documentary.

Sept. 20, 2010  -- If anyone visiting Prince Charles' home had opened the right door at just the right time, they may have been greeted with an unusual sight: the Prince of Wales laying face flat on the floor, eyes closed and ears perked in concentration.

He was, of course, trying to eavesdrop on some of the 30,000 annual tourists who pay 15 pounds each to tour his 900-acre royal estate in Gloucestershire.

That habit is just one of some curious admissions the royal makes in a new BBC documentary.

"I have eavesdropped on what visitors have said," the prince tells the BBC interviewer. "When they're going 'round outside the windows. Sometimes you've got to lie on the floor."

Charles also talks about speaking with the trees and plants in his garden.

"I happily talk to the plants and trees, and listen to them. I think it's absolutely crucial," the prince says. "Everything I've done here, it's like almost with your children. Every tree has a meaning for me."

For the man who would be king, the disclosures could be a little off putting. But not for Katie Nicholl, author of the upcoming book "William and Harry."

"He is slightly eccentric, but I think eccentric people make the world go 'round and make it a lot more fun," Nicholl told "Good Morning America."

Prince Charles was an organic pioneer long before it was hip.

"I got a lot of flak for a lot of things," Charles says in the documentary. "I mean, potty this, potty that, loony this, loony that."

But far from looney, the prince says speaking to the plants keeps him "relatively sane," according to the UK Press Association.

The full documentary is set to air on BBC 2 on Thursday at 8 p.m. local time.

Until then, Nicholl warns, "As Charles said, he does properly eavesdrop, so do mind one's words."