Calla lily have became a new bulbous crops flowers recently in Taiwan. Estimated cultural area is approximately 30 hectares. Annual cut flower production of calla lily is more than 2 million per year recently. Unstable quality of imported tubers would affect the quality or production of cut flowers. Calla lily is sympodial, with one to three dominant buds on tubers. In the tuber, dominant buds, depends on tuber size, always emerge with secondary and the tertiary buds from the leaf axils. Anatomical observation reveals flowers differentiated after planting. Spathes were found while dominant buds reached 6-cm length and the gynoecia and androecia differentiate while dominant buds were 19-cm long. Production and quality of cut flowers is highly related with tuber size. The bigger tubers produced better quality of cut flowers. GA3 can stimulate some plants flowering and the possible mechanism could be the redistribution of carbohydrates in plants to enhance the sink strength of shoot apex to flower. GA3 could possibly stimulate carbohydrates to apical meristem for flowering.