Concrete Cinder Block for raised garden beds?

I would like to build raised beds approximately 2 1/2' tall and between 3 1/2 to 4' wide (planting area). I want to construct the "walls" out of concrete cinder blocks .. I ALSO want to place a 2" thick concrete "counter or bench" top on the wall. My question is .. how far of overhang can I have for the "bench slab" on top of the "wall" without having to add braces etc? EX: if I use 6" wide cinder blocks (with rebar & concrete) .. and the wall is only between 2 1/2 to 3 feet tall .. and only being used to contain soil .. not to withstand major structural elements .. how far can the concrete bench top extend from the front of the wall?

Re-design8 years ago
I wouldn't go more than 2" and you'll have to use mesh in the conc.