That may be ok for fruits and veggies but not for buds. Foliar spraying during flower is a no-no in the marijuana grower's community as spraying the buds increases the risk for bud rot, which will kill whatever bud is affected. Just because it says something on the instructions does not mean that that is the application for marijuana. I see this a lot with lights saying that it will cover a certain footprint, which may be true for lower intensity plants, but not bud. Like everyone else is saying, stick to soil feeding in flower.