I went on a recent garden tour and saw a vegetable garden edging was that a great idea. The owner had placed bags of QuikCret in a rectangular area to make a small raised bed. He had stacked the UNOPENED bags (offset) two bags high. As rain and moisture seeped into the bags, they hardened into concrete blocks the size of the bags. The paper packaging also disintegrated, leaving the blocks looking like stone. He had also taken re-bar and stuck two down into each bag (beforehand when the bags were soft) to keep the blocks from shifting. Using re-bar wouldn't have to be done, though. I thought "How cool!"