The Olla waters by seeping water through the unglazed pottery into the ground around the buried pottery. It is an ancient practice by Native American gardeners as well as by the Spanish settlers.
Olla irrigation solves problems for gardeners who cannot irrigate frequently, and is a great solution for plants that should not be irrigated frequently. Ollas allow gardeners who travel and can not be at home to check on their plants and gardeners who are limited by water conservation ordinances to irrigate infrequently.
Ollas do not loose water to evaporation, but instead all the water sweats through the Olla into the ground. Ollas can also provide a great visual in your garden adding color and art to an otherwise drab area. Include some small boulders with the Olla, some flagstone, or even a small bird bath.