How to Use Olla Irrigation and DIY Olla Tips

Drought was not always a common phenomenon in the U.S. Yes, the Southwest was always more arid and even has desert areas, but today, areas of extended drought are increasing at a rapid pace. Greenhouse gases and climate change are seriously affecting greater areas of the western and southern states. Even in the north and east, there are lengthening periods with little precipitation and even triple-digit temperatures are not unusual.

This has led many areas to institute severe penalties for wasting water. They have also limited the consumption of water through either legislation that limits the use of water or raises the cost of water. 

Know the Importance of Conserving Water

It is important that all of us recognize water as a limited resource and take steps in our own environment to conserve water as much as possible. There are many ways to achieve a beautiful landscape and a productive garden while still remaining mindful of the need to conserve water. There are a number of water conserving garden supplies and tools that can help you save water when gardening. You can also save and store water from the roof by installing rain barrels or even a cistern. Another way to conserve water is by minimizing the size of your lawn which requires a lot of water to maintain. The key is to get creative with new tools to keep your soil hydrated.

Meet the Olla

Among all the popular garden watering tools available, the Olla is gaining popularity fast. The Olla (pronounced Oi-ya) is an ancient method of irrigating crops. It is believed that Ollas were first used in northern Africa as long as 4,000 years ago. There is also evidence that Ollas were used in China at about that same time. 

What is the Olla?

An Olla is basically a low-fired clay vessel with a narrow neck. The pot is buried in the ground with only the neck protruding above the soil. Then, crops are planted around the perimeter of the Olla at a distance based on the size of the Olla and the types of plants being grown. The Olla is then filled with water and a cover is placed on the top to prevent soil and other debris from entering the Olla and to minimize evaporation of the water from the jar.

Ideally, the gardener should only have to refill the Olla with water anywhere from once a day to once a week. Ollas should be refilled when the water reaches the 50 percent mark. As the soil becomes moist, the plants surrounding the Olla will grow toward the water source. In fact, many gardeners report that their Olla is covered with a thick mat of roots by the end of the season.

Another method of using Ollas is to connect the ollas to a water reservoir (which can be as simple as a bucket of water) and allow gravity to keep the Ollas filled with water. This requires a little upfront expense, but the saving in labor may be worth it.

Understand How Osmosis Works

Ollas work through the process of osmosis. Osmosis in biology is the movement of water molecules through a membrane from a high concentration of water molecules to a low concentration of water molecules.

Think of the Olla vessel, which is composed of porous clay, as the “membrane.” The water in the Olla is a high concentration of water molecules. The soil surrounding the Olla has a low concentration of water molecules. The process of osmosis wants the water molecules to be equal on both sides of the membrane and will move the water from the high concentration, inside the jar, to the low concentration, in the soil.

Osmosis theoretically will continue until the concentration is equal on both sides. The beauty of this system is that if it rains, the amount of water molecules on the soil side of the jar is higher, so osmosis will slow or even stop until the soil starts to dry out and then osmosis will begin again. This means it is impossible to overwater or waste water. 

Find the Best Garden Watering Tools 

Learn the Benefits of Olla Irrigation

There are many benefits to be gained from using Olla jars, including:

the Benefits of Olla Irrigation
  • Seedlings Can Be Started In The Ground—The steady moisture content of the soil ensures that the seedlings will not dry out and die. This will allow them to stay through to maturity
  • Ollas Don’t Need Level Ground—This means that hillsides or uneven ground can be used for growing because the moisture will not wash away the soil as it would if surface watering.
  • Olla Irrigation Can Be Used On Plants, Shrubs And Trees—As long as you adjust the size of the Olla to the plant’s needs, it will work well. In the case of trees, the purpose of the Olla is to get the tree off to a good start by allowing the tree to develop a good root system. The trees will be able to take care of themselves once the roots are deep enough to reach the moisture in the deeper levels of the ground.
  • Ollas Save Water—Water savings is estimated at 50-70 percent or more, compared to surface watering.
  • Ollas Don’t Support Weed Growth—Because the surface of the soil is dry, there is less competition from weeds. Plus, the weed seeds that do germinate don’t survive long enough to establish deep enough roots to reach the moisture of the Olla.
  • Add Fertilizer to Olla Water—Water-soluble fertilizer can be added to the Olla and will be transported to the plant in the water. This is more efficient and less labor-intensive.

Besides the benefits listed above, the impact of Ollas is even more pronounced in third-world countries. Many of these countries are extremely poor, and the ability to grow a subsistence garden can be lifesaving. Because the Olla vessels are low-fired, the local potter can include the Ollas in his collection of saleable goods, contributing to the local economy. The pots made locally are inexpensive and affordable to most.

Ollas have helped make land that was formerly unable to support a garden crop into a garden that can support the needs of a family. These same ancient techniques can help those of us who are facing water shortages for the first time.

Break Ground With These Garden Supplies

Research Continues on Ollas

Because most Ollas have been a traditional way of growing food in mostly rural areas, little research has been done to determine what shape of Olla is the most efficient and the most productive. The current Ollas are usually designed in a shape and size the potter prefers. More research needs to be done to determine the best shape and size of the pots and how that changes depending on the type of plant that is being grown.

Another variable to consider further research is the type of soil the pot is in. The efficiency of the pot may be compromised if the soil is clay or sandy.

4 Things to Know About Olla Irrigation

There are a few things to consider when opting for Olla irrigation systems. 

Watering an Olla

1. Ollas Can Get Costly

Depending on the amount needed, they can get costly. If you must purchase manufactured Ollas, the cost can be prohibitive. However, for areas with frequent drought conditions, they may pay for themselves by saving water costs.

2. Ollas Require Holes to Be Dug

Ollas take some effort because they have to be dug into the ground. The size of the Ollas varies. If you are using a small Olla in a container, it will be relatively easy to dig the pot into the soil. However, if the Olla is large, it may take a bit more time, effort and physical labor to get them into your soil. You can imagine if you’re looking to service a full garden, you may have to do a lot of digging for a lot of Ollas.

3. Ollas Can Be Fragile

Because the Olla is made from low-fired clay, they can be more fragile than other irrigation systems. The low-fire technique allows the pot to remain porous, which allows the water to slowly seep through the sides. Be prepared to replace your pots every few years.

4. Ollas Can’t Be Left Over Winter

The low-fired nature of the Olla means there is limited experience with using them in cold climates. In fact, there is no record of successfully keeping the Olla in the ground in areas that are below freezing in the winter. Currently, it is thought that the pots won’t survive the pressure from the freezing soil.

Because it would be impractical to dig out each Olla every fall and re-bury in the spring, this is another area of research. Could the shape of the pot allow it to survive the freeze? Could a thicker wall prevent breakage without compromising the ability of the water to move through the wall? While these questions are being investigated, it may make Ollas a non-starter for northern gardeners looking for a permanent solution.

Create Your Own DIY Olla

If you are interested in trying an Olla in your garden, it is possible to make your own DIY Olla. If you are an experienced potter, making an Olla will not be difficult. However, because most of us are not potters, here are some DIY Ollas made from pre-made manufactured clay pots.

Create A Single Pot Olla

1. Create A Single Pot Olla 

Start by purchasing large clay pots with a loose drainage saucer. First, set the saucer aside and use a cork or other plug to seal the hole in the bottom of the pot. Then, dig a hole in your garden large enough to fit the pot up to the brim. From there, insert the pot and fill in the dirt around the pot, being careful not to allow the dirt into the pot. Add water to the pot and use the saucer as a lid on the top of the pot to prevent the water from evaporating. Plant your seeds or starter plants close to the pot and just refill the pot as necessary.

2. Create A Double Pot Olla 

First, purchase two pots of identical size. Again, use a cork or other plug to seal the opening of one pot. Using a silicone adhesive, draw a bead of adhesive around the top of the pot that has been sealed with the cork. Once finished, carefully invert the unsealed pot over the original pot, matching the edges in the adhesive. Allow the adhesive to set and test for leakage at the seam, adding more adhesive if necessary.

Once the adhesive is set and there are no leaks, dig a hole in the ground large enough to accommodate the two joined pots. The open hole should be slightly above the soil level so that no soil can enter the pots. Use the open hole to fill the DIY Olla. 

Remember when you purchase clay pots for your DIY Olla project to choose unsealed pots.  If the pots are sealed, the water won’t be able to move into the soil.

Add Ollas To Your Garden

Try a few Ollas in your garden, along with other great garden watering tools and water-saving techniques. You can even add mulch to conserve moisture around your Olla and help to stabilize the temperature of the soil. This can be added protection for your Olla from unseasonable cold weather. Most importantly, have fun using this unique, ancient technique to keep your garden looking gorgeous. 


Image Credits: 
Trong Nguyen/
Dan Shachar/
Maksym Drozd/