Plans for Making Concrete Planters

Mixing Concrete

• There are two basic types of concrete mixes. A quick-setting mix will set in about 10 minutes. Mix only what you can use in a short time. Start the mix by adding one part water to five parts quick-setting concrete. Keep adding water a little at a time until the mix is the consistency of modeling clay.

  Another option is a crack-resistant concrete. This type of concrete is durable during the winter months and is impact resistant. This type of concrete mix is pourable and can be hand mixed. Add three quarts of water to a container. Pour the concrete into the water, mixing well. This type of concrete should be workable and just thick enough to still pour.

Square Planters

• Square planters require a frame, also called a form, to set the concrete in. The outer form for a planter is usually made from wood and is in two parts. The first part is a square box shape made from 3/4” plywood with four sides, but no top or bottom. The second part is the bottom, also made from plywood, but with a groove around it wide enough to set the box into. The base should be twice as thick as the box. Drill a hole that is ½” wide through the center of the base. This is where water will drain from the planter. Insert a dowel through the hole. Use cooking oil on the dowel, and coat the inside of the box and bottom with the oil, making it easier to remove the planter once the concrete is dry. The planter will need an inner form placed in the center that is filled with sand. A cardboard box will work, coated on the outside with oil, of a size that will allow for planter walls at least two inches thick. Set the outer box inside the grooves and pour concrete into the bottom of the form. Add the cardboard box that is filled with sand. Pour concrete around the outside of the cardboard box. Use a tamper to push the concrete around as you pour. Once the concrete has set, remove the inner box, the form and the dowel.

Round Planters

• Round planters are easier to make because they do not require an outer form; the planter can be cast in wet sand. Create a hole in the sand that is the size you want for a planter; find a container to fit in the cavity and compact the sand around it. Twist the container to compact the sand under it, and remove the container. Pour concrete in the hole to make a base and place an oiled dowel in the center. Insert a tubular inner form that allows for a wall thickness of at least two inches, and pour concrete around the outside of the tube. When the concrete has set, remove the inner tube and the dowel. Both planter types require the concrete to cure for at least four days.