Aluminum, steel and plastic edging is an inexpensive option available at home centers and garden stores. Edging comes in various heights and is inserted into a trench at the garden's edge. Dig the trench the exact depth of the edging to provide an invisible barrier. Make the trench an inch less than the edging product to allow a lip to show above ground. Edging typically lasts for many years and provides a maintenance-free edge for a flower bed.
Bricks and pavers make a long lasting, classic border for any garden and lend a polished, formal look. Bricks and pavers are available at home and garden stores in various sizes and colors. They can be placed vertically, horizontally or at a 45-degree angle at the edge of a flower bed. Dig a ditch to the desired depth, using the bricks as a guide. Pour a layer of gravel topped with sand to provide a stable base for the bricks. Insert the bricks level with the surface or slightly rising above it. Pour sand into the spaces between the bricks to keep weeds at bay.
For a naturalized border, use stone to edge your flower bed. Garden centers and stone yards have a wide variety from which to choose. Dig a ditch along the edge of the garden, adding a layer of gravel and a layer of sand to provide a sturdy base. Lay the stones on top of the base, adding sand between the rocks to keep weeds from sprouting. For a raised flower bed, add another layer of stone atop the first, making a rock wall. Stackable retaining blocks can be used in place of stone. The top layer is held in place with construction adhesive.
Poured concrete edging is a no-maintenance flower-bed border that lasts for years. This product is installed by concrete professionals and provides a permanent, curb-like barrier at the garden's edge. The concrete edging can be applied in a straight line for a symmetrical, formal look, or in a gentle curve for a more natural look. Many companies stamp the concrete to give it the appearance of stone, brick or other material.