Make sure you have a sprayer that has a fine particle mist, using a standard spray bottle will not do, I'd recommend doing half dose of whatever it tells you and see how it goes. Like numbers said, foliar application is more of a emergency thing, more often than not you will create other problems from improper application or improper environment and it dries it back up too fast. Best time to apply is just before lights off, but there is no benefit to applying what can just as easily be placed in soil.
Risky with minimal rewards comparable to medium application.