How to Build a Flower Bed Out of Concrete Retaining Wall Blocks

Spray paint the ground where you are installing the bed to mark the location.

Remove the sod inside the spray-painted lines. You can do this with a shovel, or by using a rototiller.

Break up the soil in the ground by working it back and forth with a garden rake, or by running over it with the rototiller.

Place the first retaining wall block into position on the dirt along the edge of the grass. Put a level on top of the block, and tap it down with a rubber mallet to even it out, if necessary.

Place another block on the ground next to the first block. Place the level across both blocks. Tap down the second block to even it out with the first block, if necessary.

Continue to install the retaining wall blocks around the perimeter of the bed, using the same method. If you can't fit a full block into place, cut it with a wet saw.

Place a second course of blocks on top of the first course. Attach the blocks in the second course to the blocks in the first course by applying a thick bead of masonry adhesive on top of the blocks in the first course. Position the blocks in the second layer so that they are staggered from the blocks in the first course to help strengthen the walls.

Fill the bed inside the blocks with a 50-50 mix of topsoil and compost. The bed is now ready for planting.