Garden Olla Test Run

In exploring irrigation options I came across the olla. An olla is a non-glazed clay pot. Traditional ollas have a wide base and a narrow neck. The olla is buried with just the top of neck left above ground. It is then filled with water and the opening covered with a rock or a lid. The water will then slowly wick out into the surrounding soil through capillary action. The dry soil draws out moisture from the olla wall until the soil is evenly saturated.

Ollas have several positive points:

  1. They minimize water lost to evaporation.
  2. They make it impossible to over water a plant because water is only released as the plant uses it.
  3. A reasonably sized olla should only have to be refilled every few days.

Negative points include:

  1. Water spread diameter is not very large. A 6″ diameter olla has about a 10″ diameter water spread according to this article. You can go with bigger ollas but with the downside of eating up more garden real estate.
  2. I can see plants with aggressive root systems enveloping an olla, clogging up the pores and potentially destroying it.
  3. Ollas are expensive. Home Depot is advertising a 10″ olla for $35

Over the past couple weeks I’ve been making ollas by gluing together a clay pot and the saucer and sealing them with silicon caulk. In the garden I want to tie them together with irrigation tubing so I only have to fill up a central reservoir and water will be distributed to all the ollas.

The olla workshop. I’m using gorilla glue to secure the saucer to the pots. After the glue is dry, I’ll caulk the seam. The pots on the left are 6″ in diameter. The ones on the right are 4″. I’ll use the 4″ ollas on a project I’m working on for our balcony.

Initial olla layout. They’re spaced 20-24″ apart.

I’ve buried the first set of ollas, inserted ‘T’ junction connectors into there necks and connected the irrigation tubing. I tried 1/4″ tubing at first but it took a long time to fill the ollas so I swithed to 1/2″. 

Experimenting with gravity feed water delivery. I connected the irrigation tubing to the bucket, filled the bucket up with water and it successfully filled the ollas. I’m toying with connecting the irrigation system with our rain water collection barrels.