Growth in lengths of tomato stems and leaves was accelerated by 5.0 μg gibberellic acid (GA2) applied to the seed, or by 5.0, 0.5, and 0.05 μg given to the roots. Treatment with 5.0 μg also decreased bud number and lengthened the time between bud appearance and fruit formation on the first truss by 1–8 days. Smaller amounts applied to roots shortened this time by 1–4 days. Indol-3yl-acetic acid at 0.5 μg had no effect, nor was simultaneous application of GA3 and IAA to the roots more effective than GA3, alone. Single applications of very small amounts of GA3 to seeds or seedling roots thus proved capable of changing growth-rates of stems, leaves, and trusses.The effects of treating tomatoes with GA2 and with cultures of Azotobacter chroococcum, which contain small amounts of GA3, and IAA, are compared.