Yes, you must discard soil root rot has touched every single time. Soil reuse causes most repeat infections in houseplant collections.
I learned this the hard way several years ago. A friend gave me soil from her garden shed to save money on potting mix. Three of my plants developed root rot within a month of using that soil. It looked fine but it carried hidden spores from a past infection.
Many people ask if you can reuse soil after root rot by drying it out first. The answer is still no. Drying your soil does not kill the fungal spores hiding inside. Those spores wait in a dormant state until moisture comes back to wake them up.
Phytophthora spores can live in your soil for many years as the Crop Protection Network reports. Pythium hangs around just as long. These pathogens make tough survival structures. They shrug off drying, cold, and heat.
Your contaminated potting soil acts like a disease bank in your home. Every plant you put in that soil faces exposure to root rot fungi. One bag of bad soil can spread infection to your whole collection over time.
UW Extension gives clear guidance on this topic. They say you should never reuse potting soil from plants that had root rot. They also warn against reusing drainage water. Spores travel in water just like they do in soil.
For proper root rot soil disposal, you need to bag the infected soil in plastic first. Tie it closed so spores can't escape into your space. Throw the whole bag in your household trash rather than your compost pile.
Your home compost pile won't get hot enough to kill these tough pathogens. Commercial composting reaches higher temps but home piles stay too cool. Don't risk spreading disease to your garden by composting infected soil.
Your pots need cleaning before you use them again too. Soak your clay and ceramic pots in 10% bleach for at least ten minutes. Rinse them well and let them dry in the sun. This kills any spores stuck to pot surfaces.
Cheap plastic pots might not be worth your time to clean at all. The cost of a new pot beats the risk of another infection. I throw away any plastic pot that held a plant with severe root rot. It's just not worth the risk to my other plants.
Fresh bagged potting mix from a store costs you just a few dollars. Losing another plant to root rot costs much more in both money and heartache. Buy new soil every time and your plants will thank you for it.
Read the full article: How to Treat Root Rot: A Complete Guide
