In this study we determined the base temperature and Heat units for leaf flushing initiation and growth of RRIM-600 and GT1 Hevea clones. The minimum base temperature was found to be approximately 16-degrees-C for leaf flushing emission and 19-degrees-C for shoot growth in terms of height. Approximately 420 degree days at 16-degrees-C as base temperature is required for successive leaf flushing initiation. Linear equations with correlation coefficients above 0.95 allow an estimation of the height increase from the accumulated degree days, corrected or otherwise for photoperiod. The highest correlation coefficients demonstrated a positive effect of the photoperiod among the factors influencing the shoot growth.3726567