Increasing winter wheat seedling growth would make it a better winter cover crop. Gibberellic acid (GA₃) seed treatment may accomplish this by stimulating stem growth. A bioassay, mimicking field conditions, could determine the relative sensitivity of conventional and semi-dwarf cultivars. In growth chambers set for cool (10℃/4℃) and warm (21℃/4℃) conditions, wheat seeds were treated with 0 and 125 to 16,000 ppm GA₃. The cultivars Goodstreak (tall or conventional) and Wesley (semi-dwarf) were compared as standards. Emergence and plant height were measured. “Goodstreak” showed a significant growth promotion at 500 ppm GA₃ when seeds were dipped and 2000 ppm when GA₃ was applied in-furrow under both temperature regimes. “Wesley” in general required the same or a higher dose of GA₃. Separately, the seeds of nine other cultivars were treated with GA₃ as the standards. Based on maximum height promotion, the most sensitive cultivars under cool conditions were Goodstreak, Harry, Millenium, and Wahoo; under warm conditions, the most sensitive cultivars were Alliance, Goodstreak, Jagalene, and Millenium. In general, the least GA₃ sensitive cultivars were Arrowsmith, Scout66, and Wesley. “Buckskin” and “InfinityCL” were intermediate. The rye cultivar Rymin also was tested and showed less sensitivity to GA₃ than “Goodstreak”. When 6 benzyladenine (6BA) with GA₃ was applied to “Goodstreak” and “Wesley” seed, emergence, plant height and weight, and tiller formation were reduced. Wheat cultivars will respond to GA₃ and differ in the amount of GA₃ needed. The results of this growth chamber study will guide subsequent field trials.