dish soap kills them instantly but dont use too much on your plant cause it will kill your plant too. get that terro liquid stuff, there food mixed with poison and they bring it back to the nest. then put a bunch of it on pieces of cardboard around your grow. it gets solid after a few days so you may have to reapply. you can also spray raid around the area of your room but never spray it on your plant or in the soil going to your plant.
understand how the enemy works. ants produce pheromones. its a chemical that we cant see but has smell to other ants. they use it as a way of communicating. also ants leave trails of pheromones everywhere they go so they cant find there way back and tell other ants where to go. a ranger ant goes off in search of food. it finds your molasses and is happy as fuck. he graps up as much as he can and on his way back to the nest he leaves a trail of pheromones. all other ants in the nest now know where to go for food. clean the area around real good to disrupt the pheromones. if you remove the pheromones, they will have to find the molasses all over again. but its not hard for them. the thing with raid is it leaves an oily residue for about a week or so. the ants hate it and cant leave there pheromones in it. just dont spray it too close to your plant. you dont want to be smoking that shit. i would normally never even recommend raid but ants can be a bitch.
also i actually dont use molasses anyone. it gets too sticky in the soil. one time 2 weeks before i harvested a plant i flushed it with 20+ gallons of water and the run off was still discolored. only 5 gal pots. people say it helps sweeten buds and that may be true, but so do other products that have carbs and work just as good if not better. i used advanced nutrients over drive and it worked great. its both a hardener and flavor enhancer. otherwise now i just use botanicare sweet raw.