Ollas are unglazed earthenware pots that provide slow deep water released directly to plant roots.
------------------------ Original April 2009 --------------------------
As the weather heats up, I’ve been thinking about how to stretch the growing season for my greens and am turning to container gardening. Containers are great because they can be moved around to take full advantage of optimal microclimates around your home. Of course, that is true of any locale, not just here in the desert. Your house and yard will have cooler and warmer spots that you could take advantage of to plant things that otherwise might not thrive in your area or season.
Container Gardens can be lots of fun - and additive!
An example of a microclimate at my house would be the front porch vs. my back patio. The front porch faces directly west, which most of the year here in the desert is perfect for planting, but in the heat of the summer, the planters are more like an easy bake oven for roots. It is impossible to keep the roots cool and damp enough on that side of the house, so I just wheel the planters to the back patio. With an eastern exposure, the plants get enough cool morning light and are protected from the worst of the afternoon sun.
Well, that worked until the temps were over 115 F, then the plants withered in their pots regardless of what I did. I’m not kidding that it was like trying to garden in your oven! So I did more research and discovered that the kind of pot you use is crucial to success. Our local garden sages advised me to forget those beautiful, lightweight resin pots and invest in the old wooden wine barrel type. The insulation and breathable nature of the wood will keep the pot from overheating in the summers. They also recommended running a drip irrigation line to the pot.
The lone survivor from last year's plantings - a sad little avacado
Well, a drip line would prevent me from taking full advantage of the microclimates by fixing the location of the pot. I firmly believe that every problem has its own unique solution and I found it in an ancient technology that has become new again – Ollas! (Pronounced Oye-yahs) The Spanish settlers and Native Americans in our area used olla pots to irrigate their gardens and conserve water. They are a superior way to provide moisture to the root zone while minimizing water lost to evaporation.
This Olla is partially buried, showing the depth of watering that can be achieved without loss through evaporation.
The olla pot is buried in the soil up to the neck and within about a foot of the plants to irrigate. It is a simple vessel of unglazed terracotta that will slowly release the water through its porous clay and deep water the root zone of the plants around it. There are different sizes depending on your application, and you could bury the olla in the ground as well as in a container garden. They are also perfect for raised beds. In order to prevent mosquitoes from accessing the water supply, put a rock or other stopper on top of the mouth of the olla.
My Garden helper hard at work in the wine barrel :)
My wonderful local nursery (Baker Nursery located on 40th Street just north of Osborn in Phoenix) carries both the wine barrels and the ollas. They also recommended the best kind of potting soil for this climate. Of course we’ll have a Container Gardening class soon and am looking forward to seeing if these techniques can be further improved upon– and will keep you posted!
If you want to know more about ollas and olla gardening, please visit these websites:
------------------------ UPDATE August 2012 --------------------------
I can't believe I've had these pots this long! Since then I've doubled the amount of these guys in our garden, I've been so impressed with the results. The ollas have been working like a charm and the soil has been so productive with a minimum of fertilizer added to it over the years. It is about time to refresh the soil as they compacted a bit and the level has dropped a few inches in them. I was also thinking about experimenting with turning one of these barrels into a wicking bed garden... see this post for more on that experiment. But I just wanted to let you all know how wonderfully these containers have survived the last few years! I'll post some pictures later, but I've got trees with veggies planted in most of them now.
------------------------ UPDATE May 2017 --------------------------
I wanted to let you all know that these ollas and the original pots are still in production in my backyard and still going strong!! I can't say enough good things about them. I've found that my 1/2 wine barrels with the large ollas can be very happy being watered every 3 days in the worst of summer and I can push it without loosing my plants to 4 -5 days, if we leave for a long weekend. Really a hard working low tech solution for our environment!
Let me also say that we have moved 2 times since I originally wrote that post in 2009 - and my gardens were able to move with me seamlessly thanks to the ollas in the pots instead of being on integrated drip systems...