Cross section of a wooden retaining wall. Wooden frame built from treated lumber, set on stone/gravel, and the back & bottom of frame is wrapped with weather proof material. Cheaper & lighter than stone wall
Raised Garden Bed Construction: If using timber, ensure that it is an untreated hardwood to prevent the risk of chemicals leaching into the soil. Pine that was treated using chromated copper arsenate, or CCA, contains a toxic chemical mix for preserving timber which can be drawn up into the plants and eat part or all of the plant. A common approach is to use timber sleepers joined with steel rods to hold them together.