How to Build Low-Cost Garden Boxes

Pick a location for your raised garden box in an area where it gets plenty of sun; it should be near a water source.

Measure out a 4-by-8-foot rectangle in the location you selected. Place a garden stick in the ground at each corner of the rectangle. Run a piece of string along each of the stakes. Adjust the location of the stakes until the corners are square and the string is straight. This is your guide for building the garden box with straight sides.

Tamp down the ground inside the rectangle, using a hand tamp, until the ground is level.

Place a row of concrete blocks around the rectangle, with the holes facing up. Use the string as a guide to keep the row straight.

Check that each cinder block is level, and tamp the ground under it if it is not. Leave no spaces between each block. Remove the stakes and string when the first row is complete.

Shovel gravel into the rectangle. Spread the gravel around until it is level with the tops of the concrete blocks. The gravel will help water drain inside the box.

Stack another row of concrete blocks on top of the previous row. Center each block over the ends of the blocks on the previous row. Continue until the entire second row is complete. Install a third row of concrete blocks in the same manner.

Shovel a large amount of planting soil into the planting box. Use a rake to spread the soil so it is level with the top row of concrete blocks.

Fill each of the holes in the concrete blocks with planting soil. Plant plants in the holes as well as in the main part of the box.