E’s problem with fungus on a pot brings up the topic of reusing clay or terracotta pots. If you reuse your clay pots — and I can’t imagine anyone who doesn’t — a simple once a year cleaning can help keep any mold, fungus or mildew spores from spreading.
First, know that a fungus is different from the minerals that leech out of the water and leave a white-ish coat or moss that leaves a lovely green coat. Many people don’t want to wash their clay pots and remove the aged look it takes time to acquire. It’s kind of like brand new tennis shoes that are stark white.
But if you want to clean your pots, here’s how:
To remove white salts/mineral deposits, coat with a baking powder and water paste, scrub with a brush and then rinse with plain water.
To clean and disinfect, scrub the inside with a brush to remove built-up soil, then soak for 30 minutes to an hour in a tub of water filled with 1 part chlorine bleach to 9 parts water. Do not add soap, just bleach. If needed, scrub the outside of the pot down. Transfer the clean pots to another tub filled with clean water. Let the pots soak for 30 minutes to help dilute the bleach that remains in the clay, which could harm sensitive plants. Place upside down to air dry.