Ollas are an ancient and very efficient method of “drip” irrigation useful for vegetable gardens, raised beds and containers.
An ancient and very efficient method of “drip” irrigation useful for vegetable gardens, raised beds and containers, an olla is an unglazed clay pot buried and filled with water. Water slowly seeps right through the porous clay wall directly into the surrounding soil.
Like drip irrigation, it’s an efficient method of providing water to the roots of growing plants. In this case, the roots eventually encompass the pot and grow deep into the soil.
The irrigation is dictated by the moisture tension in the soil itself. Once your plant’s moisture needs are satisfied, seepage from the pot stops; when the soil dries out, it begins again.
In addition to keeping your plants watered, an olla has other benefits over surface irrigation: it keeps the surface of the soil dry, to reduce weed germination. It also prevents the gardening soil from becoming compacted.
You’ll want to use an olla with a neck long enough to keep exposed above ground (for easy refilling); you’ll also want to use a lid to prevent evaporation (and mosquitos!) Although a variety of ollas are available commercially, it’s also possible to build your own by gluing small clay pots and lids together.
In general an olla may be refilled weekly, or as needed. Some users have even connected them to rain barrels in order to provide a simple method of refilling while the users are traveling.