Cement planters are a sturdy presence in your garden landscape design. Make your own cement garden planters to decorate any outdoor space. Cement molds and release agents are available commercially, but you can also use existing planters, metal bowls, coffee cans and other common household objects. One object must fit inside the other, with a 1- to 2-inch clearance around the sides. Make more than one cement planter to line a garden path, flank a front porch entrance or decorate the corners of your deck.
Seal any drainage holes in both planters with silicone sealant. The planters are the molds for a cement garden planter. Allow the silicone sealant to dry.
Hammer the five 2 1/2-inch-long nails 1/4 inch deep inside the bottom of the largest plastic planter. The nails will create drainage openings in the cement garden planter, so space them every 2 to 3 inches along the base of the planter.
Coat the inside of the largest planter and the nails with a release agent. Nonstick cooking spray will work, but you can also use a commercial release agent.
Mix the cement topping mix according to the directions on the package. Make sure you use topping mix if you prefer a smooth finish.
Pour a 2-inch layer of cement topping mix into the base of the largest planter. The heads of the nails should be visible.
Coat the outside of the medium plastic planter with the release agent. Place the medium planter inside the large planter. The base of the medium planter should rest on top of the nail heads.
Fill in the sides between the two plastic planters with cement topping mix. Allow the cement to harden overnight.
Remove the medium plastic planter. Grip the nail heads with pliers and pull them from the cement planter. Remove the cement garden planter from inside the large planter.
Allow the cement planter to cure for at least one week before planting.