I just read one of your articles about helping a plant with root rot. It recommended washing the roots under running water. I understand that one of the causes of root rot is a fungus that can grow in the soil. I want to avoid contaminating other soil, so should I wash away the soil in a sink or on a concrete surface as opposed to the backyard on the lawn so that the soil doesn't go into healthy soil? As my name suggests, I'm new to gardening.
How to Wash Roots if Your Plant Has Root Rot
The amount of soil pathogens that might wash out of the soil and into your yard won't be large enough to contaminate the outside soil. The character of the soil outdoors is completely different from soil in a pot. I recommend you don't use a sink, because of the danger of clogging your plumbing. If the plant is small enough, you might want to dunk it into a bucket of water, and just gently swish it around and use your fingers to work the soil away from the roots. Otherwise, just set it wherever is convenient and hose the root ball gently until the soil is washed away.