I hope you have a horticulture store near you that would be the best place. If you do not then I am sure you can find somewhere online. I use blackstrap molasses unsulphered and I use 2 tablespoons at the third week into the flowering stage every watering or feeding till I am to start the flushing period prior to harvest.
Safeway next to the Maple Syrup, Albertsons, Rays Market etc. I use Grandma's 1 Tbl spoon per gallon up to flush. I use 1 tbl spoon per gallon once a week in Veg and every feeding in flower up to flush.