HST (High Stress Training)

High Stress Training (HST) encompasses any canopy-manipulation technique that intentionally damages vascular or meristematic tissue to redirect growth and hormone signaling. Core HST methods include topping, FIMing, supercropping (crushing the inner fibers of a stem between fingers to induce a knuckle that strengthens the branch and flattens the canopy), main-lining/manifolding (symmetrical serial topping from a single node hub), and heavy defoliation. HST triggers wound-response signaling (jasmonic acid, ethylene) and transient photosynthetic reduction, but when timed during vegetative growth it can increase branching, yield per plant, and — as demonstrated by Danziger & Bernstein (2021) — chemical uniformity across inflorescences. HST is contraindicated within ~2 weeks of flower transition and for most autoflowering genotypes, which lack time to recover. Etymology: descriptive acronym, coined in contrast to LST in online grower communities c. 2005. Synonyms/slang: stress training, plant training, "beating up the plant." → See also: LST, Topping, FIMing, Pruning.