A circular flower bed can provide an accent around a tree or other area in your yard. You can add a touch of class to your flower bed by installing a circular retaining wall around it. Interlocking blocks are available that have a radius built into them. They create a round wall that is easy to install. Expect the project to take a weekend or less as you will not require the use of mortar to support the wall.
Place a garden hose around the area you plan for your flower bed and create a circle with it. Move it around until you are happy with the size. Once you have the shape you would like, trace around the hose with marking paint to transfer the line to the ground.
Place blocks around the painted edge and mark a second line to denote the back edge of the retaining wall. When completed you will have two painted circles on the ground. You must excavate the area between the circles.
Take the intended height of your retaining wall and multiply it 1 1/2 times. Add an additional 7 inches for the footer.
Dig a ditch between the painted lines and as deep as the number of inches you calculated in step three. Use a shovel and a rake. Make sure you have a flat bottom when finished. Pound the dirt with a metal tamper to harden the floor of the ditch.
Fill the ditch with 7 inches of river gravel and then pound the gravel with the tamper to compact it. Add a 1 inch layer of sand in the ditch, spread it out and tamp it.
Place the interlocking blocks end-to-end in the ditch and complete the first circular row.
Cut one block in half with a circular saw equipped with a masonry blade and then place it as the first block in the second row. Finish the row with standard length blocks. This will ensure no ends line up with the ends on the previous row. Repeat this for every other row you install.
Install all of the additional rows following the steps in six and seven and then backfill the center of the area with dirt to create the flower bed.