AMKhalid

the ground might be a good temporary solution during extreme conditions, but if the opportunity is there, use benches. I have had to use the ground for a couple years because I had no choice (Im a student bonsaiist) and I hate it. I have lots of insect problems, the most notable being a monstrous ant nest occupying the entire pot of my citrus tree... i had to bare root the poor thing to get rid of it.

So horitculturally, I would say that the isolation and air circulation provided by raised benches is beneficial to potted plants. When you factor in the aesthetic and functional benefits of having plants chest high or so, it seems like benches are the best solution.

good luck