Prince Charles: 'I Happily Talk to the Plants and Trees, and Listen to Them'

Talking to plants keeps him relatively sane, he says. Who knows how nutty he'd be otherwise?

"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.