I have recently seen comments and discussions on social media about reusing pots from greenhouse or nursery-purchased plants. In some instances, there has been discussion of returning pots to nurseries and greenhouses for businesses to reuse.
I’m definitely all for reusing pots whenever possible. It’s an environmentally sound thing to do. However, keep in mind that you need to be cautious when reusing pots as they potentially can be sources of disease-causing organisms. These pathogens may be carryovers from plants that you originally purchased in the pots, or they may be pathogens that the pots picked up later as the pots have be stored in your garden or elsewhere on your property. In particular, damping-off and root rot pathogens can be found in many garden soils, so anytime pots come in contact with garden soil (and it doesn’t have to be a lot), they can potentially become contaminated. And, it’s not just pathogens that can be an issue. Insect pests and (gulp!) jumping worms could also potentially be carried via contaminated soil on recycled pots.
So, if you have a collection of old pots and want to reuse them (or even more importantly want to give them to your local nursery or greenhouse), take some precautions prior to reuse or donation.
- Clean your pots thoroughly with soapy water to remove any bits of soil clinging to the surfaces of the pots that might be harboring pathogens. An added bonus of using an initial cleaning with soapy water is that this should help deactivate plant viruses that might be hanging out on your pots.
- Soak your pots in a 1.0-1.5% sodium hypochlorite solution for 20-30 minutes. Sodium hypochlorite is the active ingredient in disinfecting bleach. This treatment will help kill pathogens that remain on the surfaces of the pots. Be cautious when using bleach to avoid contact with skin, eyes and clothing.
- Thoroughly rinse the pots to remove bleach residues that can be toxic to the new plants that you are trying to grow in the pots.
Note that the treatment outlined above may not be successful in all situations. Bleach treatments tend to work better on clay or ceramic pots but tend to be less successful for plastic pots. Be that as it may, seriously consider decontaminating you pots prior to reuse or donation to local businesses. This will help limit, as much as possible, plant pathogen carryover and spread.
For more information on plant diseases and their management, check out the UW Plant Disease Diagnostics Clinic website (https://pddc.wisc.edu/) or contact PDDC staff at firstname.lastname@example.org or (608) 262-2863.