if you are in sunny southern california, i used to grow my Vandas outdoors in full sun in San Luis Obispo, brought them in for the winter and fall months.
I found that they did really well with a simple addition of osmocote general fert at about 1/4 the recommended dose. additionally, they seem to love soilmoist and orchidbark in about equal proportions.

i actually still use soilmoist for all my vandas, they grow healthier roots faster this way than i can make them grow any other. still soak them every morning, probably dont need a 15min soaking tho.