Purpose: Silicon established as a beneficial nutrient element especially for cereals, however it’s suitable source and optimum rate of application as a chemical fertilizer still not recommended. The purpose of the study was to identify the suitable source and optimum rate of silicon for growing rice at Ganges delta coastal zone soils. Methodology: Two similar succeeding field experiments: one at early monsoon season with T. Aus rice and another at monsoon season with T. Aman rice in 2021 were carried out using a two factor split plot design having replicated thrice. The first factor was three different sources of silicon (silicic acid, sodium meta silicate and calcium silicate) and second factor was seven rates of silicon (0, 1, 2, 5, 10, 20 and 40 kg Si ha-1). Results: Using a quadratic model the optimum rate of silicic acid, sodium meta silicate and calcium silicate were 32.2, 25.7 and 23.6 kg Si ha-1 for T. Aus rice, and 42.9, 25.8 and 24.5 kg Si ha-1 for T. Aman rice, respectively. Calcium silicate was the best source of silicon as it shows best response with smaller rates of silicon. Sodium meta silicate had the second and silicic acid had the lowest performance. Increasing Si rates progressively increases the Si content, Si uptake and chlorophyll content of rice. Conclusion: Calcium silicate with 24 kg Si ha-1 is recommended for rice at Ganges delta coastal zone soils.