According to the label for Bayer Advanced 2 In 1 Systemic Rose & Flower Care, you will use 1 capful for roses, per plant. For Shrubs, you will use 2 capfuls per foot of plant height. For flower beds, you will use 2 capfuls per 12 sq. ft.
This is a granular product that will be applied about the base of the plant. You will work the granules into 1-2 inches of soil and water after applying. For flower beds, spring the granules evenly over the flower bed.
Bio Advanced 2 In 1 Systemic Rose & Flower Care is not labeled to be used on marijuana or anything else edible/smokeable. It would not be safe to do so.