best shit i have ever used to kill a sativa stretch is BIG BUD from advance nutrients, it will literally stop ALL vertical growth and make the buds so damn swollen its unrealistic, i use it the first week of 12/12 with all my sativas

u sua lly a sativa will get 3x its size in the beginning of 12/12 with big bud they get probly 2" taller with crazy big buds iv even had mold issues inthe middle of my buds cause ther so thick