what time to foliar feed

I need to foliar feed my ladies because a severe case of mag def, I'm omly using epson salt, not any nutes..........when can I spray my plants, after lights out or before light on?

after lights out, or a few hours before lights on......

if your using florescents you could spray even with the lights on............

good to go, Im going to go feed them now

i feed mine while lights on when there metabilizon is peaking better absortion