Choose a location for the flower bed. Make a sketch of the round flower bed and list the plants you plan to use at the side of the drawing.
Measure the lawn or existing garden space to determine how wide the round flower bed will be.
Cut a piece of twine or rope that is 1/2 the length of the width of the round flower bed. Tie the twine to a stake. For example, cut a 3-foot-long piece of twine for a 6-foot-wide flower bed.
Insert the stake firmly into the soil at the center point of the area for the round flower bed. Pull the twine taut and walk around the stake while marking the circle with spray paint. A round outline will form.
Cut the sod with a sharp knife at the circular paint line. Dig up the area with a spade and prepare the soil for planting.
Plant the tallest plants at the center of the round flower bed. Plant a row of short flowering plants or foliage around the outermost portion of the flower bed, maintaining the round shape. Marigolds, pansies, begonias, alyssum and dusty miller are a few good choices for the circular border of the round flower bed.