Ollas (Clay Pot Irrigation)
System
Ollas are unglazed clay pots buried in the soil and filled with water. Their porous walls release moisture slowly where roots need it, making this traditional, low-tech method especially useful in dry summers. They are quiet, simple and water-wise, with no hosepipe, pump or mains-powered timer required.
How it works
Bury an unglazed olla with its neck above soil level, leaving enough room around it for plant roots to grow. Fill it with water and cover the opening with a lid, saucer or stone to reduce evaporation and keep debris out. As surrounding soil dries, moisture moves gradually through the clay walls into the root zone. Refill when nearly empty, with frequency depending on weather, soil and plant size. Test placement before planting densely, because water spreads only a limited distance from each pot.
Best for
Ollas are excellent for tomatoes, peppers, aubergines, courgettes, climbing beans and herbs in sunny beds or large containers. They suit gardeners who are away for short periods and anyone trying to use less tap water. They are less suitable for lawns, closely sown crops or thirsty plants spread across a very large area.
Tips
Use only unglazed, unsealed clay pots, as glazed pots will not seep properly. Place each olla before roots are established to avoid disturbance later. Check the water level every few days at first, then learn its rhythm. Add mulch around the planting area to slow surface drying further and protect soil structure.
Ollas (Clay Pot Irrigation): frequently asked questions
How does ollas (clay pot irrigation) work?
Bury an unglazed olla with its neck above soil level, leaving enough room around it for plant roots to grow.
What is ollas (clay pot irrigation) best for?
Ollas are excellent for tomatoes, peppers, aubergines, courgettes, climbing beans and herbs in sunny beds or large containers.
What are some tips for ollas (clay pot irrigation)?
Use only unglazed, unsealed clay pots, as glazed pots will not seep properly.
General guidance for UK gardens and allotments. Page updated 19 Sep 2026.