Reusing old flower pots is a money saver in the garden. Before you recycle those pots for new plants, it is necessary to sterilize them. Disease organisms can survive on the pot's surface, even if there is no visible dirt or debris on the flower pots. The fungus spores that cause damping-off, a fungal disease that kills seedlings, are a concern with seedling pots. Sterilize the pots once you are done using them, or right before replanting, and prevent problems that can kill plants.
Fill a sink with hot, soapy tap water. Submerge the flower pots in the water and wash off any stuck-on soil with a nylon brush.
Mix 1 part chlorine bleach with 9 parts water. Soak the flower pots in this solution for two to three hours.
Rinse the chlorine bleach solution off plastic pots with clear, running water. For clay pots, fill the sink with clear water and soak the pots for an additional three hours. The bleach permeates the pores in clay pots, and so must be soaked out.
Set the pots in a well-ventilated room and allow them to air dry completely before planting.