A field experiment was conducted during 2003 - 04 and 2004 - 05 at the Instructional Farm of Uttar Banga Krishi Viswavidyalaya, Pundibari, Cooch Behar, West Bengal, to study the effect of different levels of Farm Yard Manure (FYM) (0, 12.5, 25, 37.5 and 50 t ha-1) and GA3 (0 and 100 ppm) on production in Sweet Flag. The experiment was laid out in Factorial Randomized Block Design with three replications. Farm Yard Manure significantly affected yield and vegetative characters. GA3 also showed similar effect, except, that rhizome diameter and dry-recovery percentage were found non-significant. Interaction effect between FYM and GA3 for growth and yield parameters was found nonsignificant. Plant height, number of leaves, rhizome length, rhizome diameter and yield increased with increase in dose of FYM from 0 to 50 t ha-1 but was reverse in the case of dry recovery. Similarly, these parameters increased with application of GA3 but showed non-significant relationship, except in rhizome yield. Maximum fresh and dry rhizome yield (3013.23 kg ha-1, 1389.15 kg ha-1 respectively) was recorded with 50 t ha-1 FYM supplemented with 100 ppm GA3-, followed by application of 50 t ha-1 FYM (2879.80 and 1342.65 kg ha-1, respectively).