Minecraft wiki entry for Sapling, associated text: Applying bone meal to a block of mangrove leaves with a space underneath produces a hanging mangrove propagule with age=0. At default random tick speed (3), a hanging mangrove propagule adds 1 unit of age every ? game ticks (? seconds).[more information needed] Applying bone meal also increments the age. A mangrove propagule cannot be placed manually below a mangrove leaves.