Many overseas Chinese gardening enthusiasts, home growers, and small-scale nursery operators frequently encounter problems when purchasing vermiculite growing media. Users often report issues such as seeds failing to germinate, cuttings turning black and rotting, and potted plants suffering from stunted growth or root rot for no apparent reason. After ruling out issues with watering, lighting, and fertilization, the root cause is often discovered to be the mistaken use of industrial-grade vermiculite instead of horticultural-grade vermiculite.
While both appear to be golden-yellow, exfoliated, flake-like vermiculite and look remarkably similar to the naked eye, they differ vastly in terms of raw ore, processing standards, and impurity control. Industrial vermiculite is strictly unsuitable for horticultural use; horticultural-grade and industrial-grade vermiculite must never be used interchangeably.