Abstract
Silicon (Si) is a beneficial, non-essential element used in cannabis (Cannabis sativa L.), yet cannabis-specific evidence is scattered across hemp and drug-type cannabis. Because the marketable organ in drug-type and medicinal cannabis is the inflorescence, whose cannabinoid and terpene quality and strict residue limits make every fertigation input unusually consequential, a cannabis-focused synthesis of silicon use is needed. This comprehensive review aims to synthesize that evidence and clarify when, how, and in what form Si supplementation is justified across the crop cycle, based on a four-database search (covering the literature up to May 2026, with the cannabis-specific evidence base spanning 2019–2026). Cannabis is an intermediate Si accumulator depositing silica in bast fibers and trichomes, with benefits clearest in propagation and vegetative growth. Root Si lowers cadmium and zinc uptake and supports antioxidant defense; foliar nano-Si aids drought tolerance, and Si suppresses powdery mildew while raising tissue Si ~2.1-fold and inflorescence biomass ~1.2-fold without reducing cannabinoid or terpene quality. On current evidence, Si appears best deployed as a resilience-enhancing, stage-specific input within an integrated program rather than a universal additive. Future research should prioritize genotype- or chemotype-resolved dose–response studies on cannabinoid and terpene yields and late-flower-application safety.
