I had raised beds (about 4'x8') that I placed 2 liter soda bottles (with the tops cut off) in the bottom of the beds; then put the soil into the beds. It really helped with water conservation since any rainfall or sprinklers filled the bottles and made damp soil in the bottles instead of running straight through our sandy soil in the Gainesville, FL area.

I had read about a few golf courses putting split tires under the grass to help with water consumption. I thought the tires wouldn't be a good thing to grow food on so we came up with the 2-liter soda bottles instead. It worked well and cut down on bottles going to the landfill.