We created three 6-foot garden beds by terracing an area 18 feet long. Drainage was a big issue on this slope, so we installed a drainage pipe to catch water coming down the hill and divert it away from the house at each level. Since we built our terrace out of pressure-treated landscape timber, we used our plans to figure out how much timber to buy. If you want to build a retaining wall from stone instead, check out our video How to Build a Retaining Wall.
Proper landscaping prevents erosion and keeps excess moisture away from your home’s foundation. Terraces that are too tall can bow or collapse under pressure, and poor drainage can lead to foundation rot and health hazards such as mold. Contact a professional if you want to terrace a slope that’s very steep or if your yard has wider drainage issues.
Begin by marking an outline for the terrace location and then dividing it into three equal sections for the garden beds. To help mark the outline and ensure it’s square, use batter boards and mason strings or chalk lines. Since the area where we built our bed was up against a brick wall, we didn’t have to use additional flashing or waterproof paint. If your location lies against existing siding, you’ll need to use one or the other.
Build a reference square of landscape timbers for the first garden bed. Begin by digging a trench at the lowest point of the slope. Place the landscape timber and check it for level. Adjust as needed. You’ll use this first trench as a reference for the other three.
Before beginning any excavation, call 811 to check for underground utilities.
Add some paver base to the trench, and level it with a long level. Adjust as needed. Next, place the landscape timber inside the trench and check again for level. To make minor adjustments, use the sledgehammer to tamp down the layer of paver base, or you can stand on the timber. Once the first set of timbers are in place and level, repeat the same steps with the next three pieces.
Once the timbers are set in place and level, secure them using timber screws. For our bed, we cut a notch in the front board and ran a section of perforated pipe across the inside of the front board, then T-ed it into the side using another perforated pipe and a fitting. This will allow water to drain out of the front.
Drill a few holes in the reference square timbers, and pound some rebar down through to hold them in place. Next, add timbers on top of the reference square. Be sure to offset the joints, so the lines won’t match up.
After the second course is complete, install the perforated pipe. Begin by laying down some landscape fabric. Put the pipe on top of the fabric, spread gravel over the pipe, and then wrap the landscape fabric back over the top. The landscape fabric will help prevent weeds, dirt and debris from entering the perforated pipe. For our terrace, we used a smaller piece of pressure-treated lumber to help tie the box together and to leave enough room for the pipe to pass through.
Backfill the first garden bed using the dirt that you dug out for the timbers. Top off with additional garden soil as needed.
After the first garden box is complete, finish the second and third ones. For each bed, we used only two courses of landscape timber; however, if you’re building yours three courses or more, you’ll need to add a deadman (a piece of timber that runs perpendicular to the wall and sits down into the hill) for support. On a steep slope, a deadman will prevent the wall from moving or bowing out.
After all the garden boxes are complete, you can begin planting. We chose bushes and plants that do well in partial shade. If you’re not sure which plants to choose in your terrace garden, you can use the Lowe’s Grow Together method. Choose plants with the same number on their tags so you’ll know which plants grow best together in the same area. Check out our Plant Guide as well as How to Read a Plant Tag for more information.