A horticultural growing medium including a support matrix, the support matrix present in an amount between 60 and 80% by weight and an inorganic component. The organic component includes a moss component including at least 50% by weight moss from the sphagnum genus is composed of at least 25% hyaline cells； between 30 and 50% by weight plant derived cellulose fiber component including alone or in any combination: coir, bamboo, hemp, cocoa fiber, rice hulls, and mixtures thereof； and between 0 and 15% cork fiber. The inorganic component includes a particulate igneous volcanic material component including at least one of amorphous volcanic glass, volcanic rock. The horticultural growing medium also includes an organic soil constituent present in an amount between 20 and 40% by weight that includes between 30% and 70% by weight humus soil； between 30% and 70% vermicompost； and up to 5% by weight mammalian derived fecal matter.
