You never wanna spray before night time, and when the plants are not asleep. spraying in the stoma(I believe that what it's called) fucks it all up its clogs it so to speak and it makes the plants do weird shit I never to that before but I found out the hard way with a different brand but it Burnt the shit outta all my tops and it was throwing out some weird leafs like only the veins of the leafs and shit. But If your gonna spray I would wait till the plants are asleep