This system is discussed in Global Buckets.
Has anyone tried the Olla watering system?
Hi, yes, last year I used homemade ollas in large grocery-sized plastic/fabric bags (the kinds Whole Foods will sell you for 99 cents to be re-used for groceries) to grow bush beans and Japanese eggplant. The ollas worked very, very well, particularly when the temperatures went over 100 degrees. I could fill them up in the morning and not worry about the plants burning up. The beans were very prolific, although this year I will put fewer plants in each bag.
I also lined milk crates with landscaping fabric and put an olla in each and grew gourds, squash, and cheery tomatoes. (The squash and gourd plants did great until they got hit with powdery mildew; I think they were also too big for the crate)