A main objective of growing satsuma mandarin (Citrus unshiu Marc.) in a vinyl-greenhouse is to secure competitiveness of the products in the markets by early shipping of high quality fruits. For early shipping of the products from the vinyl-greenhouses, heating starts in early December and fruits art harvested before the end of July. Although this type of cultivation is profitable under adequate managements, it has a problem caused by unreliability of flowering, which is related to completion of dormancy. To estimate the degree of dormancy completion, a simple method has been employed by the growers to determine contests tion, of carbohydrate. In addition, a benzylamine purine treatment has been developed to promote growth of sprouts and stimulate flower-bud emergence. Further improvements art required to ensure profitability of the cultivation in a vinyl-greenhouse, including reduction of production costs and quality improvement. It costs ¥70 to 100 million to build a one-hectare vinyl-greenhouse, including heating, ventilation and irrigation systems. The fuel required for one season operation is 250 kl, or ¥7.5 million equivalent per ha for the early shipping type. Cost reduction is vital for the future development of this cultivation system.