Pot Irrigation

This post is not about watering those weeds, though pot irrigation could be used to do just that. Pot irrigation, also known as pitcher irrigation, is an old method of watering plants regaining popularity, especially in arid regions. It is a convenient way to conserve water while keeping your plants happy and healthy.

Pot irrigation used to water beans (Thamizhpparithi Maari) CC BY-SA 3.0

plant-food.htmlUnlike gravity watering systems that use inverted bottles that drain into the soil, pot irrigation uses moisture tension to irrigate plants.

What is an irrigation pot?

Irrigation pots are unglazed clay jugs that have been buried in the soil with only the upper edges above the soil line and covered with a ceramic lid or plugged with a cork. Water can seep through these unglazed pots. If the soil is already wet, the water stays in the pot. If the soil is dry, plant roots and the soil pull water from the jug, providing a steady source of water. Over time, plant roots will grow toward and wrap around the irrigation pot.

History of irrigation pots

Irrigation pots or “ollas” have been used for thousands of years. Archeologists have found them around the world, from South America to China. I can imagine that carrying water every day was quite a chore. Being able to fill irrigation pots every few days instead of watering daily would be a big attraction. In fact, I wish I had heard about pot irrigation while I still had my raised beds! I would’ve put one pot right in the middle of each 4x6 bed and saved myself a lot of time and water.

​How to use ollas

Inexpensive unglazed ceramic jugs and pots are often available at yard sales and thrift stores. They can be a bit pricey in retail stores, but you have to ask yourself what your time and water are worth. You can also use standard ceramic planter pots. Simply plug the drainage hole with a cork and use the saucer as a lid. If you want to, you could create a system of connected ollas. But that’s beyond this post.

Ollas can be filled every few days, depending on the weather and the size of your irrigation pot. Put simply, bigger pots need to be filled less often, will water larger areas, and take up more space. Generally speaking, a 3-gallon pot will water a three-foot diameter area for 3 to 7 days. In 2013, Ecology Action used five 5-gallon ollas for a 100-square-foot garden plot. Their ollas had caps that reduce evaporation and collect rain.

The important thing to keep in mind when using ollas is that they water the subsoil. Seeds and new transplants will need extra water at the surface to get established. Also, plants should be installed at least one foot away from the olla to keep young roots out of the heavily saturated soil.

Benefits of pot irrigation

Pot irrigation is said to conserve 50% to 70% of your irrigation water. That’s a lot of water! Watering from the soil also significantly reduces fungal diseases and you don’t have to mess with the garden hose as often. You can also add fertilizer to your olla, allowing plant roots to absorb those nutrients at a gentle pace while preventing up to 66% nutrient loss due to evaporation and inaccessibility. Finally, clay pots are earth-friendly. There are no plastics or chemicals to leach into your soil or food supply. You may have to monitor for slugs, however.