King Charles unusual quirks have been revealed by his biographer.

In his new book, Robert Hardman admits His Majesty loves planting trees and deeply cares about the environment.

“He does love being out and about in the countryside,” Hardman told Fox News Digital.

“He’s always disappearing, and he’s got a particular thing at the moment with planting trees.

“He’s obsessed with it. He’s always liked planting trees. He used to get mocked for it slightly because whenever he planted a tree, he’d always shake one of the leaves by the hand and say, ‘Good luck tree.’”

“He is now planting so many trees,” he told the outlet. “I talked to one of his staff, and he said, ‘Well, we often joke, “Where’s the King? He is probably planting trees.”‘

“And it turns out … he is planting trees. He’s not at his desk, he’s out in the garden,” noted Mr Hardman.