Materials for raised beds can range in both cost and effectiveness. One of the most popular materials for raised bed gardens that is sold in local garden centers is treated timber. Timbers that are pressure treated decompose slower than other building materials. Pressure-treated wood also contains no chemicals that can be released into a raised bed to harm the plants growing there.
Measure and mark the corners for the raised bed by driving stakes into them. Stretch string between the stakes to use as a guide for the walls of the raised bed.
Dig a trench along the base of the raised bed to serve as a foundation for the walls. Most raised bed foundations should extend 6 inches beneath the surface of the soil to keep grass runners from getting beneath the timbers and into the raised bed.
Drill ¾-inch holes through the center of the timbers at each end and in the center of the timber. Drill a second set of holes that is offset from the first holes by the same length as the width of the timber.
Lay a row of timbers into the trenches so they are flush with the ground with the holes aligned so that one end faces upward.
Drive rebar stakes through the drilled holes in the timber so that the rebar is one-third of the way into the ground.
Lay a second row of timber over the first around the wall of the raised bed. Thread each timber through the rebar stakes. Stagger the timber so that the second row is offset by the length of the timber.
Continue to lay rows of timber until your raised bed has reached the desired height.
Cut the rebar along the topmost timber using a hacksaw.
Line the interior of the bed with landscaping cloth. Attach the cloth to the inner lip of the timber with carpenter’s staples.
Fill the raised bed with a peat-based potting mix. Plant your landscaping plants within the bed.