Stopping nutrient input (and in hydro, running plain water) at the end of a grow with the goal of removing residual nutrients from the plant. Jeremy says this concept does not apply to living organic soil and is based on a misunderstanding of how plants use nutrients.
Jeremy says flushing doesn't apply to living soil. Because living soil's nutrients are held in organic form and released by microbes, you simply stop adding new water-soluble inputs and the system self-regulates. Forcing a flush in living soil is unnecessary and confuses the plant.