I had the same question myself 2 weeks ago after the guy at my hydro store reccomended it to me. I didn't know it was a foliar spray as well until I I got home and read the bottle. For the girls in flower I tried it and I couldn't avoid the buds, so I just sprayed the entire plant, buds and all. I didn't see anything bad happen although some of the pistils did burn but I don't care.
The calyxes themselves look a lot greener after the first spray and I tried to avoid the buds then. Now I just spray and I don't see any problems but we'll have to see how they taste at harvest. It did offset a little PM on 2 girls which is a plus in my book. The sprays seem to make the spore patches appear and grow much slower, probaby b/c it messes with their ph and or because it contains some sort of bacillus (i forgot which.)
I won't be spraying the last couple weeks though because this stuff does seem to coat the leaves (buds are probably so hydrophobic it's alright)
