Concrete planters are sturdy elements for home and garden designs. Cast your own concrete planter in sand using common household objects such as small wastebaskets or bowls as molds. Cast a concrete planter in damp sand for best results; it holds a shape better than loose sand, but it takes longer for the concrete to dry. Decorate the finished planter with stain, acrylic paints or mosaic tiles for a colorful addition to your landscape.
Make a pile of damp sand in the center of a flat work table. Flatten the center of the pile with the bottom of the large round bowl. Work the bowl into the sand until the sides of the bowl are covered around the outside perimeter with at least a 6- to 8-inch layer of damp sand. There should also be a 2- to 3-inch layer of damp sand beneath the bowl.
Remove the bowl. Smooth any cracks or fill in any spaces where the sand loses its shape. This process is like making a sand castle, but you are creating a concave hole. Line the hole with a sheet of plastic wrap.
Spray the plastic wrap with non-stick cooking spray. The spray is a release agent so the concrete planter will release easier from the plastic. Vegetable oil and commercial release agents also work.
Follow the manufacturer's directions to mix the concrete topping mix. Pour a 2-inch base of concrete mix into the bottom of the sand mold, on top of the plastic wrap.
Saw the 1/2-inch dowel into three 2-inch-long sections. Spray the sections of the dowel with the release agent. Insert each dowel into the concrete mix at the bottom of the mold. Space them 2 inches apart to make drainage holes for the planter.
Cover the outside of the medium bowl with the release agent. Fit the medium bowl inside the concrete mold, on top of the concrete mix. Fill in between the sides of the bowl and the sand mold walls with concrete topping mix. Tamp the mix down as you pour. Keep the sand walls firm by patting them as needed.
Leave the concrete planter in the mold to wet-cure for three to four days. Remove the medium bowl and the concrete planter. Push the dowels through the planter to remove them completely. Wait at least one week before decorating or planting in the planter so the concrete can cure completely.