it gives the plant b vitamins. this is helpful in times of stress and stuff like that. i dont use with with every feeding, just around times that i stress the plant...transplanting, heavy pruning/topping.
never done a side by side test but i know people who are 100% for it. thing is you can overdo it pretty easily. i think you only want like 1/4 tsp./gallon. anyway, at walmart it is like 7 bucks i think. not a bad purchase because it lasts forever and if i does work, you are reducing stress for your girls...