Terracotta is a porous material, so you need to be careful when selecting paint for your pot. Toxic paints may contain chemicals that can be absorbed by the terracotta and harm your plants. While any type of non-toxic paint should be safe to use on terracotta, some paints will flake off quickly, especially if left outdoors exposed to the elements. Look for a high quality gel medium in craft stores or art supply stores to act as a base for your homemade paint. This material bonds tightly to most surfaces, including terracotta, to keep your painted pots looking fresh as long as possible.
Mix together equal parts natural pigment powder and clear alcohol, such as vodka, to create a paste. This will prevent your finished paint from clumping.
Stir the paste into a non-toxic gel medium. If the mixture is too pale, add more pigment powder mixed with alcohol until you have reached the desired shade. Add a little water to thin the paint if it is too thick or add more gel medium if the mixture is too thin.
Paint the mixture onto the exterior of the terracotta pot with a foam brush and let the paint dry overnight.
Apply a second coat of paint, if necessary. Terracotta is porous, so it may absorb some of the paint, creating an uneven or dull finish.
Gel medium is available in matt and gloss finishes. Choose the appropriate type of medium for the look you desire on your finished pot. A matt finish appears flat while a gloss finish makes the pot look shiny.