I heard it's good to give epsom salt once in awhile, how much epsom salt per gallon of water is good? I don't want to over do it

Does anyone have a suggestion? Would it hurt to just add a couple tablespoons to the top soil of each 10 gallon pot. It would of course break down more slowly so maybe less applications would be necessary, but would the crystals cause any trouble?

I've thrown in a handful per wheelbarrow of potting
mix before,figs were fine.The stuff puts a lot of
flowers on cucumbers and tomatos,should make a lot of figs too.This is the first year I've thrown out
a handful around my inground trees.I heard you
should only do this every other year or you could
over do it.