folier spraying?

I want to fight a magnesium deficiency with a Epsom (1tsp p/g) spray.
How often should I apply it?

I am interested my self, but I will feed through soil.

I have a lockout situation. Trying to bypass roots.
Stay tuned...

i like to do it nightly.

i mix 1 TBS Epsom salt in a gallon of water and pour through the soil and then put some in a spray bottle and foliar feed with it. i do it about 1 a week until the plant looks better and then about every 3 weeks.