Minecraft wiki entry for Tree_farming, associated text: Destroying leaves does not require a tool; a sword is negligibly faster than bare hands but wears out the sword. Using a hoe increases the speed of breaking leaves, with an iron hoe able to mine them instantly. Using shears harvests usable leaf blocks for the player to pick up and later place elsewhere. Use of fire also destroys leaves quickly, but when used on a tree, fire also destroys much of the wood. Also, any leaf block unconnected or too far from a block of wood decays naturally over time.