After growing orchids for over sixty years, I found that pure molasses is one of the best fertilisers that one can use. Apply at a rate on one desert spoonful per litre poured liberally over the entire plant.
Not only will it give your orchid a good feed, it will help deter ants.
the best molasses is that you can use is direct from the sugar mill. preferably unprocessed.
Some produce stores sell it.
I also pour a mix over plants that I have just re-potted as it helps to give them a kick start.
happy growing
Myles