Mold develops easily in plant pots due to the cramped space and moisture. This mold must be removed for the health of plants that may be moved to the pot. Mold can spread and can cause problems for plants exposed to it.
There is rarely a need to throw away a good plant pot just because of mold. Whether the pot is ceramic, plastic, metal or concrete, a good cleaning and disinfecting is all the pot needs to be safe again for use.
Remove plant, if applicable. Rinse out the pot with a garden hose and then bring it indoors.
Set the plant pot in a sink and fill the sink with hot water. Put on rubber gloves, open a window for ventilation, and mix bleach with the water (you should use one-part household bleach to 10-parts water). Let this soak for several hours or overnight.
Wet a sponge in the bleach and water mixture. Scrub out the inside of the pot. Dampen a scrubbing brush in the bleach and water mixture.
Scrub off all remaining visible mold and mildew from the inside and outside of the pot. If it is difficult to get off, add a few drops of dish detergent to the brush bristles and continue scrubbing.
Wipe the sponge again over the pot. Turn on the sink faucet and rinse out the plant pot well to remove traces of bleach and detergent. Take the pot outside and set it in the sun to dry--the sun's rays will help kill any mold spores that may remain.