A field experiment was conducted in the farmer’s field of FSRD site, Kadamshahar,Godagari, Rajshahi during Rabi2017-18 and 2016-17 to select suitable planting time for onion true seed production in High Barind Tract. The experiment was laid out in a randomized complete block design with three replications. The treatments were five planting dates viz. 20 October, 30 October, 10 November, 20 November and 30 November to achieve the objective. The results revealed that the growth parameters, seed yield components, health and quality of harvested seeds were significantly influenced by the different treatments. Maximum seed yield was obtained from T4 (1.01 t ha-1 and 0.71 t ha-1respectively) when planting was done on the 20 November during the both seasons. In a similar way it was the lowest T1 (0.54t ha-1 and 0.71 t ha-1 respectively) on 20 October planting. Results showed that among the different planting dates, 20th November was the best for quality and seed yield.