Can old potting soil go bad? In terms of structure, old potting soil doesn’t change much. But many potting soils have beneficial microbes added to potting soil. These microbes enhance plant health and resilience by colonizing the plant’s root systems and extending their reach beyond the root hairs. Storing microbe enhanced potting soils in direct sunlight or in a hot place greatly reduces the effectiveness of these plant enhancing microbes. But even with good storage, most potting soils lose their umph after 2 years but still work as a mulch.
Growing Home - Can Old Potting Soil Go Bad?
