Concrete building blocks, or cinder blocks, are an inexpensive and abundant resource to use in your garden. Each rectangular block has two cut-outs that expand the possibilities. The most common use for concrete blocks is in raised bed gardening. They make a sturdy and long-lasting frame for a raised bed. Raised beds are suitable for use in small spaces and poor soil conditions because the soil in the raised bed is heavily amended to target it to the types of plants being grown.
Use a level to find a level area in full sun for your raised garden bed.
Remove all rocks and old plant matter from the garden area.
Use a measuring tape to measure the desired dimensions of your bed, keeping in mind the average length and width of a cinder block is 8-by-16 inches. Mark each of the corners with a rock or small stake.
Lay the blocks between the corner markers with the holes in the blocks facing up. Lay the blocks end to end along the sides. For corners, lay the first block of the new side perpendicular to the last block on the other side.
Stack a second layer of cinder blocks on top of the first layer if you desire higher walls. Drive a wooden stake or length of metal rebar through the holes in the corners blocks and into the soil beneath to help hold the blocks in place.
Cut a sheet of landscaping fabric to fit inside the walls of the raised bed, then lay it over the bottom of the bed.
Mix equal parts compost and quality potting soil for the raised bed. Fill the raised bed with soil mixture. Add any other fertilizers or amendments desired depending on the types of plants you are using.