Philaepnosis Orchids indoor not blooming

[Annjacob]

Hello
I am new to this board. I live in georgia in usa. I have few philanopsis varieties . I had the luck to get of 3 blooming. But the rest not blooming. I was wondering what i can do to them bloomed. Tjey are kept near a glass window inside the room east facing and they are getting adequate sunlight. In the winter we have heating on.
Do i need to use a humidifier in the winter to help them to bloom?
I water them every week , usually mix a fertiliser with the water
Pls send me your advices for indoor growing orchids to get them blooming