The zombie farmer is an undead agriculturalist who can be found in the Herblore Habitat. He will look after your fruit tree and bush patches if you pay him with vine blossoms, berries and other farming produce.
Unlike other gardeners, the zombie farmer can take care of multiple different types of crops grown in the habitat.
He is unique from other zombies in that if you ask him to protect your crops, he forms coherent sentences. This is incongruous because his reply to the "sell me items" inquiry is a display of a much lesser level of speech understanding.