Purchase or Assemble Form

• The key in making concrete planters is finding or creating a form that is sturdy for the task and will result in an attractive and functional planter. Forms can be created from almost any container from which the concrete can be slid out or released by cutting away the form. It is often helpful to have a two-piece form, with a second, smaller form to shape, compact and support the interior of your concrete planter as it cures. Large planter forms or custom shapes can be built from stick lumber and plywood into a variety of designs. Forms with texture or detail can be lined with sheet plastic or garbage bags to help ease release of the planter from the form.
  
  

Concrete Mix

• Mix concrete, water and any decorative aggregate, concrete colorants or dyes thoroughly in a tub or wheelbarrow until it roughly matches the texture of soft butter. Pour concrete mix into the form, and with gloved hands, press into the form base, working up the sides of the form. Insert your interior form, if you are using one, and press down firmly. Smooth the top rim of your planter with a small trowel, and allow to set for up at least 30 minutes. Remove the interior form, and with a small knife or trowel tip, cut out a drainage hole or multiple holes, depending on the size of the planter.
  
  

Curing

• When the concrete is firmly set but not dry, the form or forms can be removed and any seams or imperfections smoothed by gentle scraping or light sanding. Cover the planter loosely with a tarp, or place in a covered location to protect from moisture settling in or on it. Allow the concrete to cure completely for at least 10 days before filling the planter with soil, plants or watering.