The experiment was conducted at the Horticulture Research Field of Sylhet Agricultural University (SAU), Sylhet, from October 2015 to May 2016. The location of the experimental site was in the northeast corner of Bangladesh lying between 23°57? to 25°13? North latitude and 90°56? to 92°21? East longitude. The soil of the experimental field was taken randomly to a depth of 1-15 cm and chemical characteristics were analyzed from Soil Resource and Development Institute (SRDI), Regional Laboratory, Sylhet. The details about meteorological information of this area during the experimental period were collected from Regional Meteorological Office, Sylhet. The planting material of the experiment was a line of gladiolus named GL-20. The corms of this genotype were collected from Floriculture Division, Horticulture Research Centre, Bangladesh Agricultural Research Institute (BARI), Gazipur. The experiment was set up to investigate the effect of planting date and to determine optimum corm size (large, medium, and small) on the growth, flower, and corm production of gladiolus. The study consisted of two factors. Factor A: Corm size, Large (Average weight 25+2 g), Medium (Average weight 15+2 g), and Small (Average weight 10+2 g). Factor B: Planting Date, 25 October 2015 and 25 November 2015. There were (3 × 2) = 6 treatment combinations such as C1P1, C1P2, C2P1, C2P2, C3P1, and C3P2. The experiment was laid out in a Randomized Complete Block Design (Factorial experiment) with three replications. The treatments were randomly allotted in each block. The unit plot size was 30 cm × 200 cm accommodating 10 plants per plot. Spacing was maintained at 30 cm from row to row and 20 cm from plant to plant. Planting was done on 25 October and 25 November 2015. The experimental plot was first opened on the 1st week of October 2015 with a power tiller for sun curing for 7 days before the next plough. The land was then ploughed and cross ploughed several dates using a power tiller to obtain a good tilth. Ploughing was followed by laddering for breaking large soil clods and for leveling the land surface. The land was fertilized with cowdung, Urea, TSP, and MoP @ 5 t, 150 kg, 225 kg, and 190 kg ha-1, respectively. The whole amount of cowdung, TSP, and MoP was applied during final land preparation and urea was applied at 15, 30, and 45 days after germination as a top dressing. The corms were planted at a depth of 5-6 cm in furrows on 25 October and 25 November 2015. During the experimental period normal cultivation procedures weeding, mulching, Irrigation, earthing up and other intercultural operations were done whenever necessary. The spikes of gladiolus were harvested from 6 January to 25 February 2016 at the tight bud stage and when 1-2 basal flower buds opened by showing color so that these may easily open indoors one by one. Corms and cormels were harvested on 2 April 2016 and 2 May 2016 when leaves turned brown. The data were recorded on an individual plant basis from the randomly chosen five plants from each plot on following characters days to spike initiation, days to flower initiation from spike initiation, spike length (cm), rachis length (cm), number of florets spike-1, number of flower spike plant-1, the weight of single spike (g), number of corm plant-1, number of cormel plant-1, the weight of corm plant-1 (g), the weight of Cormel plant-1 (g), the yield of spike decimal-1, yield corm decimal-1, yield cormel decimal-1, etc. The data collected on various parameters were statistically analyzed by using “R” software to find out the statistical significance of the treatment effect and mean values were separated using the Least Significant Difference (LSD) test.