YES !! If you're growin in soil/peat/coco just take a small handful and sprinkle it on top before you water. Easy peasy . You can also mix it in with your watering at 1/2 teaspoon per gal. Growers sometimes use it at 1 teaspoon per gal too. Remember.. K,Ca.Mg all compete for the same nutrient uptake site.They need to stay in balanced  4-2-1 . TBS some strains are Mg hogs. Happy growin