Concrete has a natural and rustic look, and what better way to use it than for planters. Fill them with colorful flowers and place them on your patio, garden or driveway to increase curb appeal and add color to the area. You can also place them inside your home, where they look modern and chic. Making concrete planters is cheaper than purchasing them from the store and allows you to customize their size and shape according to your needs.
Determine the size and shape of the planter. Limit its width to no more than 3 feet so that you can reach the flowers in the center easily. The height can be up to 8 inches. Remember, a large concrete planter is difficult to move around due to its weight, so consider making two medium planters instead of one larger one.
Lay the plywood sheet on a flat surface to create the first mold. You need two plywood-sheet molds into which you will pour concrete for the planter, with the inner mold being 2 inches shorter in length, width and depth than the outer one. Each mold has five pieces: two similar short sides, two similar long sides and a base as wide as the short sides but equal in length to the long pieces.
Measure and mark the dimensions for the five sides of the inner mold on the plywood sheet and cut over the lines carefully with a handsaw. Do the same for the outer mold.
Assemble the inner mold by attaching the base to the sides with nails. Make sure the joints are even and flush. Lay the inner mold aside and assemble the outer mold the same way. Place the inner mold directly in the center of the outer mold. Drill a 1-inch-wide drainage hole through the bases of both the molds.
Lift the inner mold and spray its outer walls with cooking oil. Also spray the inner walls of the outer mold. The oil will lubricate the molds so they come off easily once the concrete cures.
Follow manufacturer's directions to mix concrete and water in a wheelbarrow. Insert a 1-inch-wide plastic tube into the hole in the outer mold, and pour a 1 ½- to 2-inch layer of concrete in it. Level the concrete with a hand trowel so it is even.
Insert the inner mold into the outer mold and extend the plastic tube into its drainage hole. Push it down slightly so that it rests over the concrete, and pour concrete between the walls of the molds until it is an inch below the rim. Press the inner mold to remove air bubbles.
Leave the planter to cure for 24 hours. Slide the inner mold first and hold the planter firmly as you slide the outer mold. Allow it to dry thoroughly for three days before filling it with soil and flowers.