When it comes to general landscaping, retaining walls are invaluable in giving your yard a professional look, while allowing you to add interesting shapes and contours to the space. Professionally made, they can be extremely expensive, but they always look beautiful. However, an enterprising individual with a few sacks of concrete and a garden hose can make an equally useful and elegant concrete bag retaining wall.
Level the area you intend to build the wall around, eyeballing it and digging out with the shovel. This can be a very rough process as the concrete in the sacks will shift to hug the curves of the earth.
If you are digging into the side of the hill to make more yard space, do so now.
Measure and calculate the area you'll be covering with the retaining wall.
Visit the hardware store and examine the pallets of concrete. Calculate the area of one 3-foot side on the pallet to get an idea of how many bags you will need. Purchase 5 to 10 more bags than you think you'll need.
Also, purchase enough gravel to back-fill the area and a perforated 4-inch PVC pipe as long as the wall will be.
Lay the first row of concrete sacks end-to-end a few inches away from the base of the hill. This will give you room to backfill the area, while laying the foundation for the wall itself.
Shovel some gravel onto the dirt behind the concrete bags. Tamp the gravel down by stepping on it. Lay the PVC pipe on top of this gravel with a row of perforations facing upward.
Offset the next row by about half or a third of the length of the concrete bag, while stacking it on top of the first row. Set it back about a half- to a quarter-inch so the wall will lean gently into the hill.
Fill the trench between the dirt and the concrete wall with some gravel. Flatten the gravel with your feet.
Repeat steps 6 and 7 another two or three times.
Connect your garden hose and spray down the wall. Spray until the bags are completely soaked, then continue spraying for about 10 minutes.
Allow the entire area to dry for about 24 to 48 hours.
Leave the wall to nature. Over time, the paper will fall off and decompose, leaving a smooth, concrete rock behind.
You can help this process by pulling off the paper after a month or so.