A pot experiment was conducted at the net house of Plant Breeding and Biotechnology laboratory of Agrotechnology Discipline, Khulna University, during the period from October 2012 to May 2013 to study the growth performance of orchid (Dendrobium sp.) as influenced by different NPK spray concentration. Four spray formulations: control (Tap water), spray formulation 1 (N: P: K=90:90:45 or 2:2:1), spray formulation 2 (N: P: K=135:90:90 or 3:2:2), spray formulation 3 (N: P: K=180:135:90 or 4:3:2) and two cultivars (Dendrobium Red Bull and Dendrobium Sacula Pink) were used as treatment variables. The experiment was laid out in Completely Randomized Design (CRD) under factorial arrangement with three replications. Spray formulation had significant influence on growth of the two cultivars tested. The highest plant height (18.61 cm), stem diameter (1.01 cm), leaf number (11.17), leaf length (13.42 cm), leaf width (3.05 cm), leaf area (39.89 cm2), total leaf area (455.77 cm 2 ), leaf area index (0.09), root length (3.12 cm) were found in Dendrobium Red Bull. Dendrobium Sacula Pink produced more number of roots and root diameter. The maximum plant height (19.03 cm), leaf number (11.83), leaf length (13.83 cm), leaf area (41.78 cm2), total leaf area (497.86 cm2), leaf area index (0.09) were recorded in spray formulation 3 (S3). In all the studied parameters control produced lower results. The results showed that Dendrobium Red Bull with spray formulation 3 performed better in most of the studied parameters. Further investigation is needed to find out the efficacy of spray formulation on both vegetative and reproductive stages of Dendrobium cultivars.