Many gardeners choose to clean and reuse plant pots as an eco-friendly practice. But just like dirty dishes, dirty plant pots are susceptible to carrying pathogens like bacteria and fungi.
Sterilizing plant pots is an important step that you can take to ensure a long life for both your pots and your plants. If you are preparing to repot and bring your plants inside for winter, it may be a great time to disinfect your pots! In fact, sterilizing plant pots can become a part of your fall garden cleanup as you get ready to store your pots away for the winter.
Cleaning Plant Pots vs. Sterilizing
Before you sanitize any type of used flower pot, cleaning it is crucial. Cleaning is the process of physically removing dirt, debris and germs. Plus, you can remove a good number of pathogens by cleaning your pots. But sanitizing goes a step further and will kill any germs remaining after cleaning.
Cleaning plant pots is straightforward. Remove any dried or leftover soil in the pot, and then soak the pot in a solution of warm water and dishwashing detergent. Use either a sponge, scouring pad, piece of steel wool, or wire brush to remove any visible dirt or debris as needed for the type of pot you have. For clay (terracotta pots), be sure to scrub away any mineral or salt deposits, which can pull water away from the soil. After cleaning your pot, rinse off all the soap and then set it aside for sterilizing.
Sterilizing Clay (Terracotta) Pots
Clay (terracotta) pots are porous and more likely to keep pathogens than pots built from other materials, so soaking them in a sanitizing solution will offer thorough sterilization. You can use a solution of one part bleach to nine parts water to sanitize, or about 1/3 cup of bleach per gallon of water as recommended by the Centers for Disease Control and Prevention (CDC).
For a chemical-free, eco-friendly option, sterilize plant pots with vinegar. Use a solution of one part vinegar to one part water. Soak the pots for several minutes if using bleach, or up to 30 minutes if using vinegar. After soaking, allow your pots to air dry thoroughly in the sun before using or storing them.
Your dishwasher is another effective tool to clean clay and terracotta pots. Be sure the pots are already free of soil and sand before putting them in your dishwasher. With the heat cycle turned on, dishwashers reach an average temperature of 130-140 degrees Fahrenheit (54-60 degrees Celsius), aiding in sterilization. (Keep in mind that some glazed clay pots may not be dishwasher-safe, so take care when choosing which pots to wash in the dishwasher).
After the dishwasher cycle finishes, make sure to open your dishwasher to reduce your pots’ exposure to humidity as they dry. Pathogens love water, so do your best to dry your pots in a moist-free environment.
Sterilizing Glazed Ceramic Pots
Glazed ceramic pots can be cleaned and sanitized in much the same way as terracotta pots. The only difference is, when scrubbing the pot, you will want to use less abrasive options than what you might use for unglazed terracotta. Using a non-scratch sponge, or an old toothbrush, will remove dirt without scratching the surface of your glazed ceramic pot. For stubborn spots try a mild abrasive such as a paste made of baking soda and water. Gently scrub the paste on the soiled area then rinse with water.
Sterilizing Plastic Pots
Like clay and terracotta pots, plastic pots can be easily sanitized in the solution of your choice. Follow the same sterilization guidelines as for clay pots, and dry them well before using or storing them. Since most plastics don’t begin to melt until 212 degrees Fahrenheit (100 degrees Celsius), washing them in the dishwasher is also a safe and easy option.
Sterilizing and Preserving Wooden Pots
Wooden pots, such as those made from cedar, are also porous and benefit from a short soaking in a sanitizing solution. Like clay pots, they should be dried very well after sanitizing to prevent mold or bacteria growth. Wooden pots will wear down naturally over time when exposed to moisture. Applying a wood stain or oil to your wooden planter after you clean, sanitize and dry it can help to extend its life.
Many wood stains contain chemicals that will leach into the soil and impact the health of your plants, so choosing the right stain is key. Opt for a chemical-free, non-toxic wood oil such as raw linseed oil or tung oil. Allow the oil ample time to soak into the wood and dry before potting a new plant. Or, you can stain the exterior of your planter and use a liner on the inside to protect it from rot.
Cleaning and Sterilizing Metal Pots
With proper care, metal pots may be the least likely type of pot to carry pathogens since they are non-porous. It’s not recommended to soak metal pots in either bleach or vinegar. Bleach can discolor the metal and vinegar can corrode it. To ensure the longest life for your metal pots, clean them with soap and water and dry them well to prevent rust. Make sure to store them in a dry location.
Cleaning and sterilizing plant pots can become a helpful part of your fall garden cleanup routine to make sure your pots are clean, disinfected and ready to go before spring arrives. Check out more Gardening Tips for Early Spring to learn how to prepare your container garden for spring planting.