The oya is a handmade, un-glazed terra cotta pot that can be planted in the center of the garden. When it is filled with water, the roots of crops instinctively pull themselves toward it to drink just what they need, reducing how much and how often gardeners have to water. Oyas are among the most efficient forms of low-tech irrigation known. Oyas come in sizes small, medium and large for watering garden beds roughly 1.5 feet, 3 feet and 4 feet, respectively.