How to Make a Ceramic Olla Watering System

Don’t overwater your garden! Learn to make an Olla water pot to water your plants perfectly all summer long!

olla watering system

What’s an olla watering system, you wonder? It is an unglazed porous bottle form that is buried in the garden amongst your plants. When it is filled with water, it slowly releases the water into the soil to be drawn up by your plants roots when they need it. In this project, Sumi von Dassow demonstrates how to make an olla watering system out of clay. Read on to find out how to make your very own! – Jennifer Poellot Harnetty, editor.

PS. Get tips for using your olla watering system in the July/August 2018 issue of Pottery Making Illustrated!

As pottery and cooking go hand-in-hand, so too do cooking and gardening. Potters know the pleasure of cooking and serving from hand-made dishes designed especially for homemade recipes; and every cook knows the sweetest peas and corn are those that are harvested fresh from the garden moments before they are to be eaten. To complete the triangle and bring pottery into the garden, you can make ollas to keep your thirstiest vegetable plants healthy and productive through the hottest summer weather.

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olla watering systemAn olla (pronounced oya) is an unglazed bottle made from porous clay. Filled with water and buried next to a garden plant, the olla allows water to seep slowly into the soil to be drawn up by the roots as needed. Tomatoes growing with an olla suffer less from cultural problems such as blossom-end-rot as they receive a steady supply of water. Cucumbers are less likely to grow bitter in hot weather. Pumpkins and squash can grow big and plump without splitting their skins. Ollas keep the soil from drying out but never contribute to overwatering—if the soil is moist enough, water doesn’t seep out of the porous clay. As long as you keep the olla full, the plants always have exactly as much water as they want.

For most purposes, a fairly large olla is desirable so you don’t have to fill it too often. You want a nice round bottle with a long, narrow neck so you can bury it fairly deep and leave the neck sticking out of the ground for easy filling. You can throw a bottle from 6 or so pounds of clay, trimming the excess from the foot as needed. Or, you can make a bigger bottle with less clay if you throw it in two sections.

1 Throw a wide, sturdy bowl. Cut the rim at a downward angle toward the inside, and measure with calipers.

2 Throw a second bowl to the same rim diameter. Open it up all the way to the bat. Trim the angle of the rim upward.

Two-Section Bottle

Start with 3 or 4 pounds of clay and throw a sturdy bowl on a bat. This will be the bottom section of the bottle, so don’t make it too delicate. When you cut the rim, bevel it so it angles down toward the inside of the bowl, then measure the outside of the rim with calipers (1).

With an equal amount of clay, throw a second bowl (this will be the top section), but open it all the way down to the bat, making an opening big enough to get a few fingers inside and leaving a generous amount of clay at the base. Measure the rim with calipers to make sure it matches the rim diameter of the first bowl, and bevel it in the opposite direction. This means it needs to angle down toward the outside of the rim. With the two cuts angled in opposite directions, they will fit together perfectly and make a more secure joint than two flat cuts. Don’t wire under either piece.

Allow the base bowl to stiffen slightly, so it can support the weight of the second section. Put the bat with the bottom bowl back on the wheel and pick up the bat with the second section. Flip it upside down, holding it by the bat so it stays perfectly round, and set it on the first section rim to rim, matching them up exactly (2). Use your fingers and then a stiff rib to smooth the two pieces together. Cut the top section free from the bat by running your needle tool under the edge as far as it will go, then cut it the rest of the way with a wire. Remove the bat.

3 Join the two sections together. Then, widen the opening to fit your hand and join the inside seam.

4 Create a neck by alternately pulling and collaring. You want the neck to be at least 3 inches tall and 1½ inches in diameter.

There will be a thick collar of clay where the pot was stuck to the bat. Use this clay to form a tall, narrow neck. First you need to make the opening large enough to get your hand inside to smooth the area where you joined the two sections (3). Next, pull up the neck and collar it in until it’s about three inches tall and the opening is 1½ inches or so in diameter (4).

You shouldn’t have a lot of clay to trim from around the foot, but if you feel it’s heavier than it needs to be, trim it with a trimming knife (5) or turn it over in a chuck to trim. You don’t need a foot on the bottom—in fact the bottom doesn’t even need to be flat—but you shouldn’t leave it too heavy. Water will pass through it more quickly if it’s not too thick. Bisque fire the pot.

5 Trim what you can from the base and refine the form as needed. Bisque fire the pot.

6 Bury the olla up to its neck in the soil. Plant seedlings a few inches away from the neck of the olla.

Ollas are forms commonly made by the famous Mata Ortiz potters in Mexico. See this Mata Ortiz pottery project in the PMI archives!

**First published in 2018.
  • Cynthia K.

    I’m assuming you would want to fire this at a very low temperature so that the clay remains porous but doesn’t degrade in the soil, maybe cone 06?

  • Karen N.

    What temperature you fired to was what we all want to know. Bisque temp varies widely.

  • J & C B.

    We place a rounded pebble or flat rock on top of the ollas. We also make pinch pots to fit the top so that water may be placed in them and create a “bee bath.” Otherwise, mosquitos or spiders take up residence inside the olla.

  • Ellen K.

    Good info for next year. March would be a good time to repost this article-or maybe even earlier for the Florida people.

    I could see making something similar with slabs and orange juice containers or something as molds. This may be heresy because they sure wouldn’t have the great traditional look! But they’d probably work okay as long as the mouth was wide enough to squirt water in from the hose.

    • Virginia T.

      I also need to find out which clay body to use. Earthenware or Stoneware….. Did you find out? 🙂

  • Nicole L.

    A lovely idea which I am going to try, but can I suggest for those of us in mosquito areas that a fine gauze is put over the entrance, so water can get in but insects and small animals cant.

    • Bob S.

      The illustrations seem to show a ball plugging the neck of the olla. This would prevent things getting into it. The article doesn’t mention it, but I suppose a Nerf ball or large super ball might work well. You could probably even use a cork or rubber stopper.

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