The height of raised steel planters can typically be 12" and taller, depending on the scale of the space and what you're trying to accomplish design-wise. If it's edging between two materials, it's usually 3" in total height, burying 2" below the grade. It's good to think about whether or not the steel as (a planter) would be tall enough to make an impact, short enough (as edging) to be able to walk over, but not fall into an awkward height as to be a trip hazard (between 3-6").

all really good info. What thickness/gauge do you recommend? Thank you again for sharing.

We use 3/16"