How to Create Concrete Containers for Gardening

Build an outer form with plywood. For a medium-sized container, the inner dimensions of the form should be 15" wide by 15" long by 10" high. Use ¼" plywood for the bottom and ¾" plywood for the sides.

Build an inner plywood form that is 11" wide by 11" long by 8" high. This will give the concrete gardening container a thickness of 2" on all sides.

Use a circular saw to cut three 2" pieces of PVC pipe. Place one piece in the center of the bottom of the outer form. Place the other two pieces between the center pipe and the outer edges of the form. These pipes will permit water drainage once you have planted your flowers or herbs.

Mix concrete, sand, and water according to the package directions. Coat the inner surface of the outer form with form oil to expedite removal of the plywood. Fill the bottom of the outer form with 2" of concrete and smooth it with a trowel.

Coat the outer surface of the inner form with form oil. Center the inner form inside the outer form. Make sure that it sits level on the base layer of concrete. Use a tape measure to make sure there is a 2" space between the forms on all sides.

Pour concrete between the inner form and the outer form. As you pour, use a tamper to ensure the concrete is properly compacted. Once the space is filled on all sides, use a trowel to smooth the top edge of the gardening container.

Allow the concrete to sit for 24 hours before removing the plywood forms. The concrete gardening planter should be kept damp for at least five days before planting.