Raised flower beds are freestanding gardens on top of existing soil. Contained by edging that surrounds the bed's soil, raised flower beds allow gardeners to avoid problems with the underlying soil, such as heavy compaction or poor drainage. Raised bed gardens often use purchased or amended soil that provides an ideal growing environment for plants.
Edging for a raised garden bed holds in the soil used as the growing medium. The flower bed's edging also allows gardeners to set the height of the bed to their desired level. The outline of the bed emerges through the placement of the raised bed edging, either in a standard square or rectangle or in an irregular shape with curved sides. You can also achieve a terraced effect in your landscape with a raised flower bed.
Edging sets the height of the raised flower bed, which ideally ranges between 20 and 60 cm (8 and 24 inches). The garden needs enough height to allow roots ample space to grow. If built higher, you will require a large quantity of soil to fill the raised bed. A soil depth of 209 to 30 cm, (8 to 12 inches) is adequate for most annual flowers.
Since you avoid walking on the soil in a raised garden bed, the soil resists compaction, which better allows water, air and nutrients to reach the plants' roots. Use the garden edging to create a bed small enough for you to reach the centre to perform such tasks as planting flower seedlings and pulling weeds.
The types and materials used for raised bed edging ranges from humble concrete blocks to interlocking plastic garden walls. Inexpensive options include bricks, railroad ties and landscape timbers. For beds with curved sides, choose metal and plastic edging that comes in 3 m (10 foot) lengths and installs easily with accompanying stakes. Treated wood edging will resist rot and is appropriate for use with a flower bed. When growing edible plants, however, it's safest to avoid treated timber and the risk of chemicals leaching into the soil.
Install purchased raised bed edging according to the manufacturer's directions. Metal or plastic edging comes in 3 m (10 foot) lengths installed with stakes that you pound in at intervals along the perimeter. Set up manufactured plastic garden walls with interlocking pieces and corner sections. Create garden edging with pressure treated wood and landscape timbers by first digging into the soil so the wood sits on level ground. Apply mortar between breeze block and brick garden edging for a permanent wall.