A field experiment was conducted during 2012 to 2014 to find out most suitable and cost effective weed management practice for rain fed castor on the medium black soils of central dry zone of Karnataka. The experiment consisted of ten treatments involving two pre-emergence herbicides (trifluralin and pendimethalin) alone and in combination with hand weeding / intercultivation, inter-cropping of castor + groundnut (1:3 ratio), three weedings (20, 40 and 60 DAS), farmers’ practice (one weeding at 20 DAS fb two inter-cultures at 45 and 60 DAS), two post–emergence herbicides (quizalofop-ethyl and fenoxaprop-p-ethyl, both at 0.05 kg/ha at 25 DAS) and weedy check. The pooled results of three seasons revealed that pre-emergence application of pendimethalin at 1.0 kg/ha fb one inter-cultivation at 40 DAS resulted in better weed control efficiency and seed yield (1.61 t/ha) and B:C ratio (4.3) comparable to farmers’ practice (1.33 t/ha) and three weeding (1.99 t/ha). Herbicides controlled grasses gave moderate yield comparable to farmers’ fields. Weedy check reduced the yield by 76% due to severe competition offered by grasses and broad-leaf weeds. The large scale demonstration on five farmers’ fields in Chitradurga district also revealed that pendimethalin at 1.0 kg/ha fb one inter-cultivation at 40 DAS (1.48 t/ha and 3.90) gave seed yield and B:C ratio comparable to farmers’ practice of weed control (1.49 t/ha and 3.70).