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Experiments were conducted to investigate the effects of DIFs and growth retardants on the control of stem elongation of Salvia plug seedlings (Salvia splendens ´Hot Jazz´) and their flowering responses after transplanting. Paclobutrazol (0, 1, 5, 25 ppm) or unconazole (0, 0.8, 4, 20 ppm) drenched on plug seedlings grown under different DIF regimes (+DIF: 24/16, 0DIF: 20/20, -DIF: 16/24). Lower levels of growth retardants had more distinct effects on +DIF than -DIF in inhibition of stem elongation, while higher levels of growth retardants overwhelmed inhibitory effects of DIFs themselves on stem elongation, regardless of growth retardants. After transplanting, however, flower stalk under 0DIF condition without growth retardant was much more rapidly elongated than that under +DIF condition, resulting in taller plant height under 0DIF, while, under conditions treated with growth retardants, paclobutrazol was much better than uniconazole in recovery ability of retarded stem elongation. Days to visible flower bud stage was shortened by -DIF condition and this tendency increased with increase in the level of retardants, whereas hastening effect of retardants on the flower bud development was much better under +DIF than under -DIF Finally, internode length of inflorescence showed the tendency to be reduced with increasing level of retardants rather than by the influence of DIF.
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