Ms Maggie the tin is gonna rot out pretty quick because of the constant contact with soil and moisture. Pretty fast is a relative term. It might last 10 years.
Relative indeed. We put in two beds on our AL property made just like these about 5-6 years ago and the still look great. I am 62, if they last ten years, they will have served their purpose. From the way our others in AL look, I think they will be just right. Thanks for your input though. Someone else told me me that same thing when we built the others.