Greenleaf...You've not mentioned if this grow is inside under lights or out of doors in the ground/pots. I've always 'started' with 2 TBS/gal. It will supply most of the P and K you'll need, along with micro nutrients that assist with the intake of all other nutrients. The last two weeks of flowering, I increase to 3TBS/gal. You an almost watch your buds swell; so fat and sweet. You'll not have a more mild and smooth smoke after a proper cure. I've included a site with the most definitive and detailed explanation for the wonders of molasses...B
Cannabis Chronicles