Absolutely not. While it is great to use during flower. it adds to the strength of the stems, and silica for tricome production. General rule of thumb is you should never foliar feed anything while in flower. BE careful with that stuff it can be really harmful to you lungs and other organs.its very sharp and gets embedded.its almost like fiberglass. i add it to my water to help balance the ph up,and to help kill the gnats but it has to be dry for it to work. i don't even like using it dry in my soil while in flower because it so light it can be blown by the fans into the buds.not what anyone wants or needs