06/09/2026
An unglazed clay pot can become a slow underground watering system.
That is the idea behind olla irrigation.
An olla is an unglazed clay vessel buried in the soil and filled with water. Because unglazed clay is porous, water slowly seeps through the pot walls into the surrounding soil, where plant roots can use it.
The DIY version is simple:
seal the bottom hole,
bury the pot near the plants,
fill it with water,
cover the top.
The cover matters.
It reduces evaporation and keeps dirt, insects, and mosquitoes out. UC Master Gardener guidance notes that the neck or opening should remain exposed for refilling and should be covered.
This method is especially useful in raised beds, dry climates, container gardens, and small vegetable plots.
But it is not magic.
You still need to refill it, check the soil, and place it close enough to the root zone.
The pot does not water the whole garden.
It creates a slow underground moisture pocket.
Sources: Colorado State Extension ; University of Arizona Cooperative Extension ; UC Master Gardener Program.