Concrete planters placed on sidewalks, driveways or patios or even in the garden look appealing and add interest to that particular spot. Fill your concrete planters with colorful flowers or foliage to brighten up the area and add fresh color there. Although planters made from a variety of material such as wood, plastic, fiberglass, metal and concrete are easily available in the market, you can use a few inexpensive materials to make concrete planters to dress up the place while saving on extra costs. Paint the planter so that it stands out, or leave it looking natural and rustic.
Determine the shape and size of the planter so that you can make molds for it accordingly. A square or rectangular concrete planter looks appealing against any backdrop. Keep it up to 3 feet wide and 8 to 9 inches deep.
Place the plywood sheet on a flat surface. You need two plywood molds between which you will pour concrete, with the inner mold being 2 inches shorter in length, width and depth than the outer mold. Each mold will consist of five pieces--two identical long sides, two identical short sides and a base equal in length to the long sides but as wide as the short sides.
Cut the plywood sheet for the outer mold first. Mark lines for the sides over the sheet, and cut over them carefully with a saw. Repeat the same procedure for the inner mold.
Attach the four sides of the outer mold to each other and the base with nails. Repeat the process to assemble the inner mold as well. Insert the inner mold into the outer mold, and drill a 1-inch drainage hole through both, exactly in the center.
Lubricate the molds by spraying a layer of cooking oil on the inner walls of the outer mold and on the outer walls of the inner mold so that you can easily remove the concrete planter when it sets.
Follow label instructions to mix water and concrete in a large bucket. Slide a plastic tube into the drainage hole of the outer mold. Pour a 2-inch layer of concrete over its base and level it with a trowel.
Align the inner mold over the outer mold so the plastic pipe extends into its drainage hole, and then lower it gently over the poured concrete. Carefully pour concrete between the walls of both the molds until it is level at the top. Tamp it down with a hand trowel to remove air pockets and level the top.
Allow the concrete to cure for up to 20 hours. Carefully lift the inner mold, which will come out easily due to the oil. Turn the planter over and remove the outer mold. You may need to hammer gently to loosen it. Leave it to dry for three to four days before filling it with soil and plants.