Olla Pots: The Ancient Self-Watering System for Modern Gardening

In the realm of sustainable gardening, there is one innovation that truly stands out as a testament to the wisdom of our forbearers. Any idea? Oh ja, it’s the olla! This unassuming clay vessel, with its origins tracing back thousands of years, is fast re-emerging as an ingenious solution for modern irrigation. In fact, good old Bill Mollison, the ‘Father of Permaculture’ even went as far as calling them “the most efficient irrigation system in the world”. Now that’s something!

Here, we’ll delve into the fascinating world of olla pots – exploring how they work, how they are made, and the rich history that underpins their revival as an eco-friendly irrigation technique.

How an olla works schematic diagram
Olla technology is simplicity at its best

How Do Olla Pots Work?

Olla’s (you have to talk foreign for this one – say “oy-yahs”) function on a simple yet effective principle: porous clay allows water to gradually seep into the surrounding soil, directly hydrating plant roots. By minimizing surface evaporation and runoff, this method reduces water wastage by up to 50-70%. Olla’s essentially create a localized moisture reservoir at what is known as ‘field capacity’ – that point where plants can get water but there is not so much excess that it drains away. Because roots draw from this reservoir only when and if needed, overwatering your plants is essentially impossible.

To put it simply, an olla pot is buried in the soil near the plants it’s meant to irrigate. As the soil dries out, water slowly seeps out of the pot, maintaining a consistent level of moisture around the plant roots without wasting any. Olla pots are particularly beneficial for arid climates or regions facing water scarcity, as they significantly reduces the amount of water needed to keep plants hydrated.

Olla’s as an irrigation system work very well for all plants – put them in your vegetable beds or flower pots, next to a young tree you want to give a head start to, or use them as a nifty vacation irrigation system when you next go away!

The Art of Crafting Olla Pots

A potter will either turn olla pots by hand on a wheel, or mass produce them using a mould. Olla’s can be all shapes and sizes but their most distinctive feature is their porosity and permeability.  Clay is carefully chosen and processed to ensure the right balance – allowing water to escape at a slow and steady rate.

After casting or moulding, the pots are fired at high temperatures to ensure durability. Olla pots are left unglazed, as the porous nature of the clay is crucial to their effectiveness. A popular DIY version uses two normal terra cotta garden pots that are sealed together, but results all depend on the porosity and permeability of the material used.

The mesmerising process of turning an olla

History of Olla Pots: A Journey Through Time

While the olla is thought to have originated in North Africa, the best records come from China, where they have been in use for over 2000 years. Today, they are still used in rural subsistence farming communities in many dry regions, from India and Iran to Brazil and Burkina Faso.

The word ‘olla’ originates from the Latin cultures, where it describes any flat bottomed, pot-bellied pot. Olla’s were used in ancient Rome for cooking, storage and in ceremonial use. It is interesting to note that in Gallo-Roman culture, the olla is often carried by Sucellus, who was often identified with agricultural, and well, wine.

Was Sucellus preaching the benefits of irrigation olla’s, or just sipping on a bit of vino? Probably the latter, as olla’s have long been used to keep water and other liquids cool. As the water ‘sweats’ from the clay surface, the process of evaporation cools it. Many street vendors in places like India can still be seen using this method to store milk or water.

Reviving Tradition: Olla Pots in Modern Gardens

As we deal with unpredictable climate and water shortages, as well as entertaining that 21st-century need for efficiency, the renaissance of olla pots in modern growing practices couldn’t be timelier; especially in South Africa where we are no strangers to drought.

One of the greatest advantages of olla pot irrigation is its simplicity. No complex systems or energy-intensive mechanisms are required – just the age-old wisdom of allowing clay and nature to work together. Olla’s work better than drip irrigation because once the  soil is saturated, no more water is drawn out of the olla – plants are never overwatered and water is never wasted.

Whether you’re cultivating a small backyard garden or managing a larger agricultural plot, integrating olla pots can lead to significant water savings and healthier plants – all for very little time and energy input.

Setting Up Olla Irrigation: A Step-by-Step Guide

  1. Choose the Right Pots
  2. Prep the Pots
  3. Bury the Pots
  4. Fill and Test
  5. Mulch and Maintain

  1. Choose the Right Pots: Opt for unglazed, porous clay pots. Their size should match the watering needs of your plants; any and all plants will love it! You can try the two-pot DIY version, or check out our beautifully handmade olla’s here.
  2. Prep the Pots: Fill the olla’s with water an hour before installation and leave to stand. This primes the clay and prevents it from drawing too much moisture from the soil initially.
  3. Bury the Pots: Dig holes in the soil near the plants you want to irrigate. Bury the olla pots up to their necks, leaving the opening exposed. The guide in the image below will help you plan for how many olla’s you need, and how to space them.
  4. Fill and Test: Once buried, fill the pots with water, pop the lid on to prevent evaporation, and monitor how quickly they release moisture into the soil. How often you fill your olla depends on your soil, rainfall, and how many plants the olla is feeding, but you’ll soon work it out by monitoring for a few days. Bank on anything from every two days for a small olla in a dry climate to once a week or longer for a bigger olla without much demand on it. There are also plenty of nifty drip line irrigation setups that can be incorporated.
  5. Mulch and Maintain: Apply a layer of mulch around the olla pots to further conserve moisture. Regularly check the water level in the pots until you know what they like, and refill as needed.
How to space irrigation olla's in your garden
Spacing your olla pots in your garden depends on the plants’ needs, soil qualities, and olla sizes

Did You Know?

You can fill your olla’s with used grey water – the clay will filter out any impurities as the water soaks through. We have even heard claims that the clay will do the same for salt water, but we’re yet to test that.

Olla’s will last for many years and can be dug up and re-used as often as you like, though you will have to clean away all the roots that are clinging to them! If you are planting an olla with a young tree, however, it is likely the roots will eventually crush the olla as they envelope it, though by this time the tree should have deep enough roots not to necessitate irrigation. When an olla breaks like this, the natural clay will just break down and become part of the soil.

Olla’s can also be used to store drinking water – as the clay surface sweats, it will cool the contents inside.


The journey of olla pots from ancient civilizations via a detour to wine-splashing Romans and now to modern gardens, showcases its timeless utility in providing efficient and sustainable irrigation. By harnessing the physical properties of clay and water, this unassuming vessel has become a symbol of ecological innovation; the perfect water, time and energy saver.

Being a region prone to droughts, southern Africa could do very well to invest in utilising this simple and effective technology to conserve a resource which will very soon be even more valuable than it already is.

Some links and references:

  1. https://www.permaculturenews.org/2010/09/16/ollas-unglazed-clay-pots-for-garden-irrigation/
  2. https://desertoasisgarden.wordpress.com/2015/05/10/the-ancient-science-of-ollas/
  3. https://www.gallifreypermaculture.com.au/wp-content/uploads/2012/11/Ollas.pdf

One Response

  1. John and Stephany: How much would a single pot cost of about 2 litres; and may I place an order for one in due course?

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