Terracotta pots offer an inexpensive, eco-friendly way to glam your garden. However, terracotta's porous nature can present a number of problems. If the pot isn't properly cleaned, it can develop white, fuzzy mould that's ugly and unhealthy to breathe. Even clean pots eventually develop lichen and mould on them, not something that's good for your plants. To make sure you and your plants are protected from fungi, seal your terracotta pots before using them.
Fill a large, clean plastic bucket with about a gallon of distilled water. Add a tablespoon of bleach to the water.
Place your terracotta pot in the water and let it soak overnight. The bleach should kill any bacteria or fungi spores in the pores of the pot.
Remove the pot from the water, set it in a cool, dry place and let it dry for about 48 hours. This ensures the pot is dry from the inside out.
Dip a sponge brush into some terracotta sealer, available at garden supply stores. This sealer is specially made to make terracotta pieces waterproof.
Brush the sealer onto the inside of the pot in long, even strokes. Coat the bottom, sides, rim and inside of the drain hole with sealer. Allow the sealer to dry for at least two hours.
Add two more coats of sealer to the inside of the pot and let the pot dry overnight. Seal the outside of the pot the same way, coating even the bottom.
If you want to paint or decorate your pot, seal the inside first. Paint the design onto the outside of the pot and then seal the decorated surface.