Construction Details for Gently-Sloped Landscape Edging at a Planter

Leveling the Slope

• The slope requires leveling where the planter walls are constructed. Achieve this by digging into the ground around the perimeter of the planter site. Use a spade to cut into the slope and remove the soil to create a flat-bottomed trench. Use a carpenter's level to ensure the trench is level on all sides. Filling the trench with a 3-inch layer of crushed rock and tamping it down firmly prevents the planter walls from eventually settling and become uneven.

Planter Materials

• Stone and wood work best for the planter walls. Use treated wood so it doesn't rot where the walls are in contact with soil on the slope side of the planter. The material used determines the width of the installation trench. The height of the slope determines how many layers of stone or the height of the wood planks required to construct the planter edging. A low stone or paver planter consisting of two tiers doesn't usually require mortaring, although a steeper slope and higher planter will require some mortar so the slope-side of the planter doesn't collapse.

Installation

• Construct a box from wood to the dimensions of the trench. Make the box high enough so the side on the slope sits 4- to 6-inches above the soil surface. Connect the corners with wood screws. Use 2-by-2-inch stakes to further strengthen the corners if the planter box is more than one board high. Stone is laid directly in the trench. Use masonry construction adhesive to secure each tier of stone together. Stagger the joints between the stones for each tier; otherwise, the stone sides are weakened and may collapse inward. Build up the wall so the stones sit one tier above the soil surface on the slope-side of the planter.

Finishing Touches

• Fill the planter with quality soil after completion. For stone planters, wait at least 24 hours so the masonry adhesive can completely cure. Add soil to within 3 inches of the top of the planter box edging. Plant the desired plants inside the box. Adding a 2-inch layer of bark or wood mulch provides a clean, finished look to the planter and prevents grass and weeds from blowing in from the slope above and growing inside the planter. Keep the grass along the planter edge on the slope-side trimmed with a string trimmer so it doesn't grow over the top of the planter walls.