Regimes of irrigation and nutrition are factors that influence notably the growth, development and flowering of Dendrobium orchids. The research has focused on evaluating the effects of watering regime and nutrition on the ratio of flowering of Dendrobium varieties as HT1, HT2, and HT3 in winter crop in the Northern Vietnam and given the result that the tightening measure by stopping watering for 3-5 days brings the ratio of flowering plants in the winter nearly 50% and high number of flowers/twig, flower spike length. The different ratios of N: P: K significantly influence the number of branches/ plant, number of internode/branch, plant height, leaf length, leaf width, number of leaves/branch, fallen leaves and productivity but lightly affect the size of three Dendrobium orchid breeds, flowers.  Among the experimental fertilizer formulas, the ratio of nitrogen: phosphorus: potassium as 1:3:3 has been suitable for mature plants in winter crop to increase cold tolerance and have good growth and development ability.