Conserving Water in the Garden: The Olla

We’re in the season of popup thunderstorms. That means hot days where some places can get drenched, while others get passed over for rain altogether. Lately, we’ve been passed over, which means we’re checking daily on the water needs of our garden and container plants. I mulch, work toward increasing moisture-conserving organic matter in the soil, and we have our rainwater tanks. Even so, I’m always on the lookout for new ideas. This book is loaded with them.

Gardening with Less Water: Low-Tech, Low-Cost Techniques; Use up to 90% Less Water in Your Garden by David A. Bainbridge. This book has a lot of interesting, low-tech ideas for water conservation, many of them gleaned from arid parts of the world. The one you see pictured on the cover is called an olla (oy-ya).

An olla is basically a terra cotta pot. They are often used for cooking or for evaporative cooling of foods (zeer pot). In the garden, it’s used to hold water for nearby plants. Mostly buried, its porous walls allow for a slow transfer of moisture to the surrounding soil. Brilliant and effective.

Ollas like the one pictured on the book cover can be purchased, or one can DIY. For a small olla, the materials list is short: an unglazed terra cotta planter, saucer to serve as a lid, and a way to plug the drain hole.

Some people plug the drain hole with a bit of concrete. Dan cut disks from plastic coffee can lids and glued them down with RTV, a silicone product used for automotive gaskets.

Anything that would make a watertight seal would do. RTV is just what Dan had handy.

To make a larger olla, use two pots and plug the hole in only one. Glue the second upside-down on top of the first. The drainage hole of the top, upside-down pot is where the olla is filled with water.

Next, they’re buried up to the rim.

And filled with water.

The inverted saucer becomes the lid.

The saucer lid keeps debris from falling into the water and is easy to remove to refill with water.

For the lid for my second olla, I cheated somewhat. The large saucer I needed was twice the price as the one with the same circumference as the top of the pot. So it doesn’t fit over the pot, it fits on top of it.

As you can see, I weight it with a rock. Hey, it works!

We check the water every couple of days and fill the ollas as needed. So far, so good. My thyme hasn’t dried out yet, which is a relief. My front yard herb beds tend to dry out quickly, even with a good layer of mulch. That means every little bit helps!

Obviously, the larger the olla, the less frequently it needs refilling. My recommendation is to get the largest pots you can, or make the double-pot olla (or both).

I’ll close with a couple of links for more photos and ideas for olla irregation.

• How To Use Olla Irrigation at the Water Use It Wisely website.
• Olla  – The Most Efficient & Oldest Irrigation System in the World at Living Center Oregon.