Here's a win-win for saving your back, gardening from a seated position, and helping to save the environment: Refrigerator/Freezer gardening!
Using a popular service (mark that Craigslist) I obtained free of charge twelve refrigerators, less my gas to haul them, that would have wound up in a landfill! I hope to post pictures on my site soon to show what I have done and how I did it. If you would like to leave feedback or suggestions, shoot me a note!