I`ve grown herbs on my balcony since 1986 quite sucesfully, you`ll find that most herbs don`t like too much feed at all, many are quite happy in plain soil for many years with nothing but rain water and tap water during dryer seasons.
a general rule of thumb though, is that if it`s a leafy type of herb (basil, parsley etc..) a little nitrogen is good for them on occasion, perhaps a little potash (potassium) if they flower (chives, rosemary etc..) and if it`s for roots (ginger especialy) a little Phosphorus won`t hurt
but you`ll find that you`ll not really NEED to add any, but if you do, be sure that the plant will only take what it needs and your food liquid or solid will not make your herbs inedible in anyway!
the worst that can happen is that you`ll be wasting the food or you`ll burn the roots if the plant is very young or your mix is too strong.
all plant food is safe on edibles, except where mixed with herbicides or pesticides, but a drop of baby-bio or miricle grow won`t hurt a thing