Over Feeding? wormcastings+nutes

alrite im about to pickup some worm castings as im about to repot some plants. i was wondering is there a chance of over feeding them when i add nutes ? do i even need nutes or can they just feed off the castings?

Yes it's possible. What kind of soil are you using?

seedling soil , i have mixed sand/soil/perlite together and now i wanna add the castings