Olla means pot in Spanish. Irrigation using unglazed clay pots started thousands of years ago perhaps in China. The Spanish brought the idea to the Southwest. Today gardeners in Pakistan, Iran, India and South America also use pots for irrigation.
In all these areas, consistent access to water improves plant growth and increases yield from your veggies. Without them, drying spring winds can kill tender young seedlings between automatic drip system “on” cycles.
Filled with water, a buried clay pot waters nearby plants slowly and deeply via capillary action through the porous sides of the pots. Round pots with big bellies and narrow necks may be purchased on the Internet; but they are expensive. In Prescott, Watters and Mortimers carry a few.
Low cost ollas can be constructed from very inexpensive clay pots availble at Amazon or at big box stores. The size of the pots you choose will determine how often you need to refill. During monsoon rains, removing lids will allow nature to replenish the pots with water. You could use your drip system to refill. Or you can fill them with a watering hose.
Eight to ten inch pots and their lids are easily found locally. #5 rubber stoppers, a wine cork, silicon caulk, hot glue or reusable sticky tack may be used to plug the hole in the bottom of the pot.
Using stoppers, cork, or sticky tack plugs meants you can remove the plug and use the pot for something else later. Place the lid (saucer) on top after burying the pot or you can use a masonry bit to drill a hole in the lid to collect rain water or attach a drip line. Painting the lids with acrylic paint, cuts down on evaporation.
Roots may accumulate around the clay pots; but this is a good thing. It means the roots are absorbing nearly 100% of the water. After the season, remove the pots and give them a scrub before storing over the winter.
Doubling up pots works well in the vegetable garden or near trees. You can use ollas in containers or for indoor plants as well.
- Clay pots (unglazed)
- Material to plug the hole
- Lid (saucer)
- Glue (Gorilla glue)
- Plug the hole
- Bury the pot near plants.
- Fill the pot with water
- Cover with the saucer
- Invert one pot over another
- Glue the pots together
- Allow the glue to setup overnight
- Seal seam with caulk or glue
- Plug the bottom hole.
- Bury the double pot.
- Fill with water.
No need for a lid, but a small rock or shard from a broken pot will keep critters out.
In Zone 7 and above, you may be able to leave the pots buried over the winter without having them crack and be destroyed by frost. At higher elevations, you need to dig them up and store them in the garage or shed. In marginal areas, a few inches of mulch might keep them safe.
Getting water to the roots of plants takes some effort. Clay pot ollas can help us keep plants healthy and and productive by using water more effectively. And they are easy to make.