Abstract: Growth regulator is an important factor to enlarge the flower size in the floriculture industry. Flower growers have a lot of interest in making flower enlargement and shorten longevity to harvest flower earlier and to make it marketable soon. Gibberellic Acid (GA3) and aluminium sulphate Al2(SO4)3 play significant roles in flower enlargement and development. Hibiscus sp. was used in this experiment. The branches were dripped with the respective chemical [GA3 and Al2(SO4)3 100ppm] at 3 days intervals for 3 weeks. It had been shown that the 100 ppm GA3 played major role in developing a bigger size of the flower, production of more leaves, shorter longevity of flower, quicker bloom and greater size and weight of the flower as compared to the Al2(SO4)3 and control. Chlorophyll content (represented by SPAD value) and fluorescence were higher in GA3 treated branch than in aluminium sulphate treated branch and control. The quantum yield (Fv/Fm) was maximal in GA3 treated branch. The aluminium sulphate treated branch also showed the similar results but the longevity of the flower had the longer duration in aluminium sulphate treated branch than in GA3 but shorter than control. The results showed that these two chemicals [GA3 and Al2(SO4)3 100ppm] using dripping technique instead of spray were effective for the enlargement of flower size and shorten the flower longevity with less chemical cost and quantity of chemicals without hazarding the environment instead of spray . In addition, it improved the weight and increased the blooming rate and could be acceptable to the flower growers easily and could be harvested for commercial purposes earlier.