Ten-week-old potted A. mangium seedlings were subjected to a growth retardant, paclobutrazol (PP333), at concentrations of 0, 0.5, 1, 4 and 12 g/l. Four methods of application were tested namely S, soil drenching at week 0; Fl, foliar spray (potting soil protected from chemical) at week 0; F2, foliar spray (potting soil protected from chemical) at week 0 and 6; and S+F, soil and foliar spray (potting soil exposed to chemical spray) at week 0. Plants were harvested after 12 weeks for various growth measurements. Height and leaf area increments, transpiration and stomatal conductance were monitored at weekly intervals. Paclobutrazol was found to be effective in reducing root and shoot growth, transpiration and stomatal conductance of the seedlings. Treated plants had higher root to shoot ratios. The effects of the chemical increased with increasing concentration and frequency of application for the foliar spray. The chemical was most effective when applied through the soil either by drenching (S) or soil and foliar spray (S+F).