Pruning

Pruning is the selective removal of vegetative plant organs — leaves, shoots, or branches — to manipulate source-sink relationships, canopy architecture, and microclimate, and thereby to modulate yield quantity and secondary-metabolite distribution (Danziger & Bernstein 2021a). In cannabis, pruning encompasses several named protocols: lollipopping, removing lower branches and "popcorn" buds that receive suboptimal photosynthetic photon flux density to concentrate photoassimilates in the upper canopy; defoliation, removing fan leaves to improve light penetration and airflow, reducing Botrytis risk; and schwazzing, aggressive defoliation events typically at day 1 and day 21 of flower (popularized by the trade publication Three A Light, 2016). Danziger & Bernstein (2021a, b) demonstrated that architectural manipulation — bottom-branch-and-leaf removal (BBLR) combined with defoliation — increases chemical uniformity of cannabinoids across the plant by improving light penetration to lower inflorescences. Etymology: Anglo-Norman proignier, "to cut back." Synonyms/slang: training, thinning, "leafing." → See also: Topping, LST, HST, Yield (Industry).