A neat edge and border to a flower bed provides three functions. Edging and borders give flower beds a clean, finished look and define the boundaries between a flower bed and your lawn. At the same time, a well-maintained border keeps mulch inside a bed. Edging and borders also keep out weeds such as grass, which spreads on runners above the ground and stolons beneath the ground.
Lay out the shape of your flower bed with a measuring tape. Drive stakes into the corners of the bed with a rubber mallet to serve as markers and tie strings between the stakes to show the boundaries of the bed. Mark the border of the bed on the ground by pouring a line of flour around the border. Flour will wash away from your lawn quicker than spray paint, and is more environmentally friendly.
Sharpen the flat tip of a garden spade with a flat file. This will help you to make crisp cuts into the soil with your spade.
Insert the spade into the soil around your flower border to a depth of 6 inches. Lift the soil from the border so that the flower bed slopes down into the trench and meets the flat line of the border.
Rake soil from the trench to create a neater slope. Loose soil should slant on the flower bed side of the trench at a 75-degree angle.
Plant low-growing perennial flowers or shrubs at the point where the soil begins to slope downward the borders of the flower beds. Locate border plants so that the lowest plants are in the front of the border. Place taller border plants in the interior of the flower bed. Some good examples of low-growing border plants include petunias, dwarf blueberry or ornamental grasses such as blue wheatgrass.