How to Waterproof Terra-Cotta Pots

When something's not broken, you don't fix it. Terra-cotta pottery was used in ancient civilizations, and gardeners still favor terra-cotta pots for a number of planting projects today.

Terra-cotta is a kind of earthenware that's made from clay and fired to the point that it's strong but still porous. Its porousness is what makes terra-cotta a popular material for both outdoor use and indoor container gardening. Waterproofing terra-cotta pots is only necessary if you're growing certain kinds of plants or planning to paint the pots. In this case, sealing terra-cotta pots for painting takes just minutes of effort.

Because terra-cotta pots are almost always sold unglazed, some people might wonder whether these pots need to be sealed or waterproofed before they're used. If you're simply planning to use the pots to grow things as opposed to painting them, they don't really need to be waterproofed.

The terra-cotta will gradually absorb water from the soil between waterings. Many types of common houseplants flourish with minimal water, so the porousness of the unglazed terra-cotta isn't a problem as long as you water plants often enough that they don't dry out completely. (Stick a finger a few inches into the soil to check whether it's damp or needs watering.) Things like succulents and herbs do very well growing in unsealed terra-cotta. Any terra-cotta pot used for planting should have a drainage hole at the bottom to prevent water from becoming trapped and stagnant.

If you're planning to grow something that needs a lot of water, like ferns, you might not want to use an unsealed terra-cotta pot that will cause the soil to dry out. Using a sealant can make terra-cotta a more appropriate environment for these thirsty plants. It's also a good idea to seal terra-cotta pots before painting them so the paint sits on top of the clay instead of soaking into it. You may also want to apply sealant after painting to protect the paint from fading or being washed away.

Before sealing terra-cotta pots for painting or planting, get them as clean as possible. Any dirt or debris on your pots will be permanently shellacked to the surface once you apply sealant. Clean dirty terra-cotta pots outdoors with a hose, dish soap, and a scrub brush. Let them dry before sealing.

Sealing terra-cotta pots is as easy as giving them a quick coat of paint. Use a multipurpose waterproofing spray, which you might also use to waterproof things like painted garden decor and outdoor wooden furniture, or paint on a layer of water-based sealant that dries to a clear finish. Work outdoors if you're using an aerosol waterproofing product.

If you're sealing terra-cotta pots for painting, you can choose to seal just the portion of the pot that you'll be painting (presumably the outside and maybe the top few inches of the inside).

Terra-cotta's smooth surface makes it easy to paint. Once the sealant has completely dried, use acrylic paints to decorate your pot however you like. Choose outdoor acrylics if you plan to display painted pots outside. Give them an all-over coat of one color, paint them with flower designs, or combine paint with plaster of Paris to make aged-looking terra-cotta pots with antique style.

The easiest way to paint a terra-cotta pot is generally to place it upside down on newspaper so you can paint the entire base and bottom of the pot. Let the paint dry completely before turning the pot right side up to paint the lip and inside. After the first coat dries completely, add more paint if you wish or apply another coat of sealant to finish the project.