Reusing plant pots for seed starting or transplanting flowers is an economical way to make use of items you already have. Disease organisms and insect eggs can live on the surface of the pots and spread to the soil then to the plant when you reuse the pot, but lastic and clay pots can be sterilized with minimal effort. All flower pots should be sterilized with a bleach solution to inhibit the chances of infection or infestation.
Rinse old soil and dirt from the pots using clear water. Scrub the surface with a bristle brush to remove caked on soil and soil in the crevices of clay pots.
Fill a large bucket with 9 parts water and 1 part household chlorine bleach. Soak the pots in the bleach solution for one to three hours. Plastic pots usually are fine with a one-hour soak, but porous materials such as clay require a longer period.
Rinse the bleach solution off plastic pots with clear, running water. Soak clay pots in a clear water for three hours so any excess bleach leaches out of the clay. Allow the pots to air dry completely once they are finished soaking.
Store the pots away from garden soil and any other gardening equipment that may reinfect the pots with disease organisms until you are ready to replant in them. Place them in a plastic garbage bag to further protect them from reinfection.