Hi, I just replied to another post but I thought it may be some help for you to hear this as well. I just went on a tour of a farm in Texas where they were using these things called "Grow bags" or "root pouches" or something like that. I'm going to try to upload a picture for you. They are biodegradable bags that you would be able to line your patio with. DSC_0046 (3).jpg They had a lot of them there so maybe you could contact them if you haven't found a solution yet (Google aquaponics and earth sustainable living).