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Ollas – An Ancient System of Irrigation

Olla (pronounced “oh-yah”) is Spanish for “clay pot”. These unglazed terracotta pots are used by indigenous people throughout Latin America for irrigation; but they were first used in China and North Africa more than 4,000 years ago. From there, the technique spread throughout arid regions of the world. The use of ollas saves us gardeners time, energy, and water. The clay pot is buried up to its neck in the garden, with only the top of the olla showing above the soil surface. The olla is filled with water and the top covered. These unglazed, terracotta pots are porous, so the water is slowly released deep into the soil, where the roots of nearby plants grow towards them and absorb the water. If the soil becomes dry, the roots will even pull water out of the olla when they need it. In the late fall, I dig mine up, and roots from that year’s plants are still wrapped around the ollas.

Ollas are inexpensive (especially if you make your own) and they maximize garden output while minimizing overwatering, runoff, and water loss. I live in the dry, southwest, so ollas are ideal. Not only is it hot here during the summer, but we are also a mile high, which means surface water can easily evaporate. But since the water in ollas is released beneath the surface, this isn’t an issue. Also, plants don’t undergo stress cycles due to lack of water and/or overwatering.

Ollas are best for crops with a fibrous root system such as squash, melons, tomatoes and chiles. Also, plants with a shallow root system, such as lettuces and herbs, fair well.

To use your ollas:

1) Bury them in the soil, leaving about 1-2” above the soil so that dirt doesn’t get inside. Always cover the tops to prevent water loss.

2) Place them about 2-3 feet apart in your garden.

3) Check the water level and refill as needed.

4) Dig up your ollas at the end of the season before the weather freezes to prevent cracking. Wash and put away for next year.

Happy gardening!

Resources: › Water › Irrigation

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